Grain size is a major determinant of grain weight and a trait having important impact on grain quality in rice. The objective of this study is to detect QTLs for grain size in rice and identify important QTLs that hav...Grain size is a major determinant of grain weight and a trait having important impact on grain quality in rice. The objective of this study is to detect QTLs for grain size in rice and identify important QTLs that have not been well characterized before. The QTL mapping was first performed using three recombinant inbred line populations derived from indica rice crosses Teqing/IRBB lines, Zhenshan 97/Milyang 46, Xieqingzao/Milyang 46. Fourteen QTLs for grain length and 10 QTLs for grain width were detected, including seven shared by two populations and 17 found in one population. Three of the seven com- mon QTLs were found to coincide in position with those that have been cloned and the four others remained to be clarified. One of them, qGSIO located in the interval RM6100-RM228 on the long arm of chromosome 10, was validated using F2：3 populations and near isogenic lines derived from residual heterozygotes for the interval RM6100-RM228. The QTL was found to have a considerable effect on grain size and grain weight, and a small effect on grain number. This region was also previously detected for quality traits in rice in a number of studies, providing a good candidate for functional analysis and breeding utilization.展开更多
A recombinant inbred line population derived from a super hybrid rice Xieyou 9308（Xieqingzao B/Zhonghui 9308） and its genetic linkage map were used to detect quantitative trait loci（QTLs） for rice yield traits und...A recombinant inbred line population derived from a super hybrid rice Xieyou 9308（Xieqingzao B/Zhonghui 9308） and its genetic linkage map were used to detect quantitative trait loci（QTLs） for rice yield traits under the low and normal nitrogen（N） levels. A total of 52 QTLs for yield traits distributed in 27 regions on 9 chromosomes were detected, with each QTL explaining 4.93%–26.73% of the phenotypic variation. Eleven QTLs were simultaneously detected under the two levels, and 30 different QTLs were detected under the two N levels, thereby suggesting that the genetic bases controlling rice growth under the low and normal N levels were different. QTLs for number of panicles per plant, number of spikelets per panicle, number of filled grains per panicle, and grain density per panicle under the two N levels were detected in the RM135–RM168 interval on chromosome 3. QTLs for number of spikelets per panicle and number of filled grains per panicle under the two N levels, as well as number of panicles per plant and grain density per panicle, under the low N level, were detected in the RM5556–RM310 interval on chromosome 8. The above described QTLs shared similar regions with previously reported QTLs for rice N recycling.展开更多
Organic phosphorus（P） is an important component of the soil P pool, and it has been proven to be a potential source of P for plants. The phosphorus utilization efficiency（PUE） and PUE related traits（tiller number...Organic phosphorus（P） is an important component of the soil P pool, and it has been proven to be a potential source of P for plants. The phosphorus utilization efficiency（PUE） and PUE related traits（tiller number（TN）, shoot dry weight（DW）, and root dry weight） under different phytate-P conditions（low phytate-P, 0.05 mmol L^-1 and normal phytate-P, 0.5 mmol L^-1） were investigated using a population consisting of 128 recombinant inbred lines（RILs） at the vegetative stage in barley. The population was derived from a cross between a P-inefficient genotype（Baudin） and a P-efficient genotype（CN4027, a Hordeum spontaneum accession）. A major locus（designated Qpue.sau-3 H） conferring PUE was detected in shoots and roots from the RIL population. The quantitative trait locus（QTL） was mapped on chromosome 3 H and the allele from CN4027 confers high PUE. This locus explained up to 30.3 and 28.4% of the phenotypic variance in shoots under low and normal phytate-P conditions, respectively. It also explains 28.3 and 30.7% of the phenotypic variation in root under the low and normal phytate-P conditions, respectively. Results from this study also showed that TN was not correlated with PUE, and a QTL controlling TN was detected on chromosome 5 H. However, dry weight（DW） was significantly and positively correlated with PUE, and a QTL controlling DW was detected near the Qpue.sau-3 H locus. Based on a covariance analysis, existing data indicated that, although DW may affect PUE, different genes at this locus are likely involved in controlling these two traits.展开更多
1000-grain weight （ TGW） is one ot the three component traits ot the grain yiela in rice （Oryza sativa L）. This study was conducted to validate and fine-map qTGWl. 1, a minor QTL for TGW which was previously locat...1000-grain weight （ TGW） is one ot the three component traits ot the grain yiela in rice （Oryza sativa L）. This study was conducted to validate and fine-map qTGWl. 1, a minor QTL for TGW which was previously located in a 3.7-Mb region on the long arm of rice chromosome 1. Five sets of near isogenic lines （NILs） were developed from two BC2F4 populations of the indica rice cross Zhenshan 973/Milyang 46 The NIL sets consisted of two homozygous genotypic groups differing in the regions RM11448-RM11522, RM11448-RM11549, RM1232-RM11615, RM11543-RM11554 and RM11569-RM11621, respectively. Four traits, including TGW, grain length, grain width and heading date, were measured. Phenotypic difference between the two genotypic groups in each NIL population was analyzed using SAS procedure GLM. Significant QTL effects were detected on TGW with the Zhenshan 97 allele increasing grain weight by 0.12 g to 0.14 g and explaining 8.30% to 15.19% of the phenotypic variance. Significant effects were also observed for grain length and width, whereas no significant effect was found for heading date. Based on comparison among the five NILs on the segregating regions and the results of QTL analysis, qTGWl. 1 was delimited to a 376.9-kb region flanked by DNA markers Wn28382 and RMl1554. Our results indicate that the effects of minor QTLs could be steadily detected in a highly isogenic background and suggest that such QTLs could be utilized in the breeding of high-yielding rice varieties.展开更多
A thorough understanding of the quantitative trait loci （QTLs） that underlie agronomically important traits in crops would greatly increase agricultural productivity. Although advances have been made in QTL cloning,...A thorough understanding of the quantitative trait loci （QTLs） that underlie agronomically important traits in crops would greatly increase agricultural productivity. Although advances have been made in QTL cloning, the majority of QTLs remain unknown because of their low heritability and minor contributions to phenotypic performance. Here we summarize the key advantages and disad- vantages of current QTL fine-mapping methodologies, and then introduce a sequential QTL fine-mapping strategy based on both genotypes and phenotypes of progeny derived from recombinants. With this mapping strategy, experimental errors could be dramat- ically diminished so as to reveal the authentic genetic effect of target QTLs. The number of progeny required to detect QTLs atvarious R2 values was calculated, and the backcross generation suitable to start QTL fine-mapping was also estimated. This mapping strategy has proved to be very powerful in narrowing down QTL regions, particularly minor-effect QTLs, as revealed by fine-mapping of various resistance QTLs in maize. Application of this sequential QTL mapping strategy should accelerate cloning of agronomically important QTLs, which is currently a substantial challenge in crops.展开更多
Stripe （yellow） rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks （Pst）, is one of the most important wheat （Triticum aestivum L.） diseases and causes significant yield losses. A recombinant inb...Stripe （yellow） rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks （Pst）, is one of the most important wheat （Triticum aestivum L.） diseases and causes significant yield losses. A recombinant inbred （RI） population derived from a cross between Yanzhan 1 and Xichang 76-9 cultivars was evaluated for resistance to wheat stripe rust strain CYR32 at both the seedling and adult plant stages. Four resistance quantitative trait loci （QTLs） were detected in this population, in which the major one, designated as Yrql, was mapped on chromosome 2DS. The strategy of using the Brachypodium distachyon genome, wheat expressed sequence tags and a draft DNA sequences （scaffolds） of the D-genome （Aegilops tauschfi Coss.） for the development of simple sequence repeat （SSR） markers was successfully used to identify 147 SSRs in hexaploid wheat. Of the 19 polymorphic SSRs in the RI population, 17 SSRs were mapped in the homeologous group 2 chromosomes near Yrql region and eight SSRs were genetically mapped in the 2.7 cM region of Yrql, providing abundant DNA markers for fine-mapping of Yrql and marker-assisted selection in wheat breeding program. The effectiveness of Yrql was validated in an independent population, indicating that this resistance QTL can be successfully transferred into a susceptible cultivar for improvement of stripe rust resistance.展开更多
In this study, we considered five categories of molecular markers in clonal F1 and double cross populations, based on the number of distinguishable alleles and the number of distinguishable genotypes at the marker loc...In this study, we considered five categories of molecular markers in clonal F1 and double cross populations, based on the number of distinguishable alleles and the number of distinguishable genotypes at the marker locus. Using the completed linkage maps, incomplete and missing markers were imputed as fully informative markers in order to simplify the linkage mapping approaches of quantitative trait genes. Under the condition of fully informative markers, we demonstrated that dominance effect between the female and male parents in clonal F1 and double cross populations can cause the interactions between markers. We then developed an inclusive linear model that includes marker variables and marker interactions so as to completely control additive effects of the female and male parents, as well as the dominance effect between the female and male parents. The linear model was finally used for background control in inclusive composite interval mapping （ICIM） of quantitative trait locus （QTL）. The efficiency of ICIM was demonstrated by extensive simulations and by comparisons with simple interval mapping, multiple-QTLmodels and composite interval mapping. Finally, ICIM was applied in one actual double cross population to identify QTL on days to silking in maize.展开更多
The bay scallop and Peruvian scallop are economically important species.Interspecific hybrids of these two scallops outperformed both of their parent species in multiple growth traits but exhibited decreased fertility...The bay scallop and Peruvian scallop are economically important species.Interspecific hybrids of these two scallops outperformed both of their parent species in multiple growth traits but exhibited decreased fertility,which provides good models for the study of heterosis and species divergence.Genetic mapping serves as a chromosomal-level framework to investigate the molecular mechanisms of hybridization and introgression.In this study,high-resolution linkage maps were constructed for the bay and Peruvian scallops with an interspecific hybrid family.The linkage map of the bay scallop covered over 98.9% of the whole genome with 2994 mapped markers and the average marker interval of 0.32 cM.For the Peruvian scallop,1585 markers were mapped with the average maker interval of 0.51 cM,covering 97.7% of the genome.Both the two linkage maps have 16 linkage groups,corresponding to the haploid chromosome number of the two species.Approximately,54.5% of markers exhibited significant deviation from the expected Mendelian ratio of segregation,lending in sights into the intrinsic incompatibility between the two species.QTLs related to growth and shell coloration were detected,which could explain 13.1%and 74.9% of the phenotypic variance,respectively.This represents important information for further evaluation.These findings are an important addition to the genomic resources for scallop genetic studies,and are especially useful for investigations on genomic incompatibility for hybridization,genome evolution of closely related species,and genetic enhancement programs in aquaculture.展开更多
In this paper,we propose generalized fiducial methods and construct four generalized p-values to test the existence of quantitative trait locus effects under phenotype distributions from a location-scale family.Compar...In this paper,we propose generalized fiducial methods and construct four generalized p-values to test the existence of quantitative trait locus effects under phenotype distributions from a location-scale family.Compared with the likelihood ratio test based on simulation studies,our methods perform better at controlling type I errors while retaining comparable power in cases with small or moderate sample sizes.The four generalized fiducial methods support varied sce-narios:two of them are more aggressive and powerful,whereas the other two appear more conservative and robust.A real data example involving mouse blood pressure is used to illustrate our proposed methods.展开更多
Rice (Oryza sativa L.) eating and cooking quality is mainly influenced by its starch properties. Mapping quantitative trait loci (QTL) for starch properties not only helps us understand their genetic basis leading to ...Rice (Oryza sativa L.) eating and cooking quality is mainly influenced by its starch properties. Mapping quantitative trait loci (QTL) for starch properties not only helps us understand their genetic basis leading to acceleration of quality improvement, but also helps us find possible genes participating in the synthesis of starch. A recombinant inbred line (RIL) population consisting of 107 lines, derived from an indica (Zaiyeqing 8, ZYQ 8) and a japonica (Jingxi 17, JX 17) rice, was used to investigate the genetic factors affecting starch quality parameters, such as apparent amylose content (AAC), gel consistency (GC), starch pasting viscosity parameters, gel textural properties, gelatinization temperature (GT) and starch retrogradation properties. A total of 44 QTLs covered chromosomes 2-6, 8, 9 and 11 were detected for the 22 traits, with at least one QTL and as many as four QTLs for each individual trait. The results indicated that two major genes were responsible for most starch property traits. The Wx gene that encodes granule bound starch synthase on chromosome 6 was significant for AAC, GC, starch pasting viscosity parameters, gel textural properties and starch retrogradation properties. The alk gene linked with Wx on chromosome 6 was significant for starch gelatinization temperature characteristics. All other QTLs were minor genes. One QTL on chromosome 9 flanked by RZ404 and G295 was significant for gel hardness (HD), gumminess (GUM), chewiness (CHEW), peak temperature of retrogradated starch (RTp), and percentage retrogradation (R%) and all these traits were not tested before.展开更多
Quantitative trait loci（QTL） for percentage of chalky grain,degree of chalkiness,and endosperm transparency were detected using 3 recombinant inbred line populations derived from crosses between parental lines of co...Quantitative trait loci（QTL） for percentage of chalky grain,degree of chalkiness,and endosperm transparency were detected using 3 recombinant inbred line populations derived from crosses between parental lines of commercial three-line hybrids of indica rice.Two of the populations showed great variations on heading date,and the other had a short range of heading date variation.A total of 40 QTLs were detected and fell into 15 regions of 10 chromosomes,of which 5 regions were detected for 1 or more same traits over different populations,2 were detected for different traits in different populations,3 were detected for 2 or all the 3 traits in a single population,and 5 were detected for a single trait in a single population.Most of these QTLs have been reported previously,but a region located on the long arm of chromosome 10 showing significant effects in all the 3 populations has not been reported before.It was shown that a number of gene cloned,including the Wx and Alk for the physiochemical property of rice grain,and GW2,GS3 and GW5 for grain weight and grain size,could have played important roles for the genetic control of grain chalkiness in rice,but there are many more QTLs exerting stable effects for rice chalkiness over different genetic backgrounds.It is worth paying more attentions to these regions which harbor QTL such as the qPCG5.2/qDC5.2/qET5.2 and qPCG10/qDC10/qET10 detected in our study.Our results also showed that the use of segregating populations having high-uniform heading date could greatly increase the efficiency of the identification of QTL responsible for traits that are subjected to great environmental influence.展开更多
The quantitative trait loci （QTLs） for the dead leaf rate （DLR） and the dead seedling rate （DSR） at the different rice growing periods after transplanting under alkaline stress were identified using an F2：3 pop...The quantitative trait loci （QTLs） for the dead leaf rate （DLR） and the dead seedling rate （DSR） at the different rice growing periods after transplanting under alkaline stress were identified using an F2：3 population, which included 200 individuals and lines derived from a cross between two japonica rice cultivars Gaochan 106 and Changbai 9 with microsatellite markers. The DLR detected at 20 days to 62 days after transplanting under alkaline stress showed continuous normal or near normal distributions in F3 lines, which was the quantitative trait controlled by multiple genes. The DSR showed a continuous distribution with 3 or 4 peaks and was the quantitative trait controlled by main and multiple genes when rice was grown for 62 days after transplanting under alkaline stress. Thirteen QTLs associated with DLR were detected at 20 days to 62 days after transplanting under alkaline stress. Among these, qDLR9-2 located in RM5786-RM160 on chromosome 9 was detected at 34 days, 41 days, 48 days, 55 days, and 62 days, respectively; qDLR4 located in RM3524-RM3866 on chromosome 4 was detected at 34 days, 41 days, and 48 days, respectively; qDLR7-1 located in RM3859-RM320 on chromosome 7 was detected at 20 days and 27 days; and qDLR6-2 in RM1340-RM5957 on chromosome 6 was detected at 55 days and 62 days, respectively. The alleles of both qDLR9-2 and qDLR4 were derived from alkaline sensitive parent ＂Gaochanl06＂. The alleles of both qDLR7-1 and qDLR6-2 were from alkaline tolerant parent Changbai 9. These gene actions showed dominance and over dominance primarily. Six QTLs associated with DSR were detected at 62 days after transplanting under alkaline stress. Among these, qDSR6-2 and qDSR8 were located in RM1340-RM5957 on chromosome 6 and in RM3752-RM404 on chromosome 8, respectively, which were associated with DSR and accounted for 20.32% and 18.86% of the observed phenotypic variation, respectively; qDSR11-2 and qDSR11-3 were located in RM536-RM479 and RM2596-RM286 on chromosome 11, respectively, which were associated with DSR explaining 25.85% and 15.41% of the observed phenotypic variation, respectively. The marker flanking distances of these QTLs were quite far except that of qDSR6-2, which should be researched further.展开更多
High temperature stress (HTS), an increasingly important problem in rice production, significantly reduces rice yield by reducing pollen fertility and seed setting rate. Breeding rice varieties with tolerance to HTS a...High temperature stress (HTS), an increasingly important problem in rice production, significantly reduces rice yield by reducing pollen fertility and seed setting rate. Breeding rice varieties with tolerance to HTS at the flowering stage is therefore essential for maintaining rice production as the climate continues to become warm. In this study, two quantitative trait loci (QTLs) underlying tolerance to HTS were identified using recombinant inbred lines derived from a cross between an HTS-tolerant rice cultivar 996 and a sensitive cultivar 4628. Pollen fertility was used as a heat-tolerance indicator for the lines subjected to HTS at the flowering stage in field experiments. Two QTLs that affected pollen fertility, qPF4 and qPF6, were detected between RM5687 and RM471 on chromosome 4, and between RM190 and RM225 on chromosome 6, by using the composite interval mapping (CIM) analysis. The two QTLs explained 15.1% and 9.31% of the total phenotypic variation in pollen fertility, and increased the pollen fertility of the plants subjected to HTS by 7.15% and 5.25%, respectively. The positive additive effects of the two QTLs were derived from the 996 alleles. The two major QTLs identified would be useful for further fine mapping and cloning of these genes and for molecular marker-assistant breeding of heat-tolerant rice varieties.展开更多
Quantitative trait loci（QTLs） of grain traits were detected to provide theoretical basis for fine mapping and molecular marker-assisted breeding of grain traits in japonica rice.Using an F2 population including 200 ...Quantitative trait loci（QTLs） of grain traits were detected to provide theoretical basis for fine mapping and molecular marker-assisted breeding of grain traits in japonica rice.Using an F2 population including 200 individuals derived from a cross combination between two japonica rice DL115 with large grain and XL005 with small grain,the grain length,grain width,grain thickness,ratio of grain length to width and 1 000-grain weight were evaluated in Beijing;and the quantitative trait loci for above five grain traits were identified by composite interval mapping using SSR markers.The results showed that the five grain traits exhibited a normal continuous distribution in F2 population,indicating they were quantitative traits controlled by multiple genes.A total of 16 QTLs conferring the five grain traits were detected on chromosomes 2,3,5 and 12,respectively.Eight QTLs,namely qGL3a,qGW2,qGW5,qGT2,qRLW2,qRLW3,qGWT2 and qGWT3,were major QTLs and explained 15.42,40.89,13.54,33.43,13.82,13.61,12.51 and 10.1% of the observed phenotypic variance,respectively.Among them,qGW2,qGT2,qRLW2 and qGWT2 were mapped in same interval RM12776-RM324 on chromosome 2.The marker interval RM12776-RM324 on chromosome 2 was common marker intervals of four major QTLs,and the two SSR markers RM12776 and RM324 would be used in molecular markerassisted breeding in japonica rice.The modes of gene action were mainly additive and partial dominance.Four QTLs＇ alleles were derived from small grain parent XL005,and other 12 QTLs＇ alleles were derived from large grain parent DL115.The alleles from larger parent were showed significant effects to grain length,grain width,grain thickness and 1 000-grain weight.展开更多
Grain yield and heading date are key factors determining the commercial potential of a rice variety. Mapping of quantitative trait loci （QTLs） in rice has been advanced from primary mapping to gene cloning, and head...Grain yield and heading date are key factors determining the commercial potential of a rice variety. Mapping of quantitative trait loci （QTLs） in rice has been advanced from primary mapping to gene cloning, and heading date and yield traits have always attracted the greatest attention. In this review, genomic distribution of QTLs for heading date detected in populations derived from intra-specific crosses of Asian cultivated rice （Oryza sativa） was summarized, and their relationship with the genetic control of yield traits was analyzed. The information could be useful in the identification of QTLs for heading date and yield traits that are promising for the improvement of rice varieties.展开更多
Seed dormancy contributes resistance to pre-harvest sprouting. Effects on respective quantitative trait loci （QTLs） for dormancy should be assessed by using fresh seeds before germinability altered through storage. ...Seed dormancy contributes resistance to pre-harvest sprouting. Effects on respective quantitative trait loci （QTLs） for dormancy should be assessed by using fresh seeds before germinability altered through storage. We investigated QTLs related to seed dormancy using backcross inbred lines derived from a cross between Nipponbare and Kasalath. Four putative QTLs for seed dormancy were detected immediately after harvest using composite interval mapping. These putative QTLs were mapped near C1488 on chromosome 3 （qSD-3.1）, R2171 on chromosome 6 （qSD-6.1）, R1245 on chromosome 7 （qSD-7.1） and C488 on chromosome 10 （qSD-IO.1）. Kasalath alleles promoted dormancy for qSD-3.1, qSD-6.1 and qSD-7.1, and the respective proportions of phenotypic variation explained by each QTL were 12.9%, 9.3% and 8.1%. We evaluated the seed dormancy harvested at different ripening stages during seed development using chromosome segment substitution lines （CSSLs） to confirm gene effects. The germination rates of CSSL27 and CSSL28 substituted with the region including qSD-6.1 were significantly lower than those of Nipponbare and other CSSLs at the late ripening stage. Therefore, qSD-6.1 is considered the most effective novel QTL for pre-harvest sprouting resistance among the QTLs detected in this study.展开更多
Mercury （Hg） is one of the most toxic heavy metals to living organisms and its conspicuous effect is the inhibition of root growth. However, little is known about the molecular genetic basis for root growth under ex...Mercury （Hg） is one of the most toxic heavy metals to living organisms and its conspicuous effect is the inhibition of root growth. However, little is known about the molecular genetic basis for root growth under excess Hg2＋ stress. To map quantitative trait loci （QTLs） in rice for Hg2＋ tolerance, a population of 120 recombinant inbred lines derived from a cross between two japonica cultivars Yuefu and IRAT109 was grown in 0.5 mmol/L CaCI2 solution. Relative root length （RRL）, percentage of the seminal root length in ＋HgCI2 to -HgCI2, was used for assessing Hg2＋ tolerance. In a dose-response experiment, Yuefu had a higher RRL than IRAT109 and showed the most significant difference at the Hg2＋ concentration of 1.5 tJmol/L. Three putative QTLs for RRL were detected on chromosomes 1, 2 and 5, and totally explained about 35.7% of the phenotypic variance in Hg2＋ tolerance. The identified QTLs for RRL might be useful for improving Hg2＋ tolerance of rice by molecular marker-assisted selection.展开更多
A rice residual heterozygous line （RHL） carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously. The resultant...A rice residual heterozygous line （RHL） carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously. The resultant F2：3 population was used to detect quantitative trait loci （QTLs） for three yield traits, the number of spikelets per panicle （NSP）, the number of grains per panicle （NGP） and grain yield per plant （GY）. Two QTLs for NSP, one QTL for NGP and one QTL for GY were detected, all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B. Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other. Two F2 populations and two near isogenic line （NIL） sets segregating in two sub-regions of interval RM111-RM19784 were developed. The two QTLs for NSP were validated, of which one had major effect and was co-segregated with heading date gene Hdl, and the other had smaller effect and was located in an upper region linked to Hdl. The two regions also showed significant effects on the number of filled grain and grain yield, although the effect on the number of filled grain was less consistent.展开更多
Abscisic acid （ABA）, as one of the foremost signaling molecules in plants, is an important hormone which plays versatile functions in regulating developmental process and adaptive stress process. A set of introgress...Abscisic acid （ABA）, as one of the foremost signaling molecules in plants, is an important hormone which plays versatile functions in regulating developmental process and adaptive stress process. A set of introgression lines were previously generated via a backcrossing program using an elite indica cultivar rice Teqing （O. sativa L.） as recipient and an accession of Yuanjiang common wild rice （O. rufipogon Griff.） as donor. In this study, the previously developed introgression lines were evaluated for ABA sensitivity. Here we reported that a total of 14 quantitative trait loci （QTLs） associated with ABA sensitivity were identified. An ABA sensitive introgression line, YIL53, was identified and characterized. Physiological characterization, including chlorophyll content, malondialdehyde content, soluble sugar content, and stomata movement, demonstrated that YIL53 exhibited the characteristics associated with ABA sensitivity. Genotypic analysis revealed that YIL53 harbored one QTL related to ABA sensitivity, qASS1-2, which was located on chromosome 1 within one introgressed segment derived from the Yuanjiang common wild rice. Furthermore, the qASS1-2 was finally narrowed down to a 441-kb region between simple sequence repeats （SSR） marker RM212 and single nucleotide polymorphism （SNP） marker M3 using the segregation population derived from the cross between Teqing and YIL53, and three candidate genes associated with ABA sensitivity were identified using a strategy combined gene expression analysis with QTL mapping. Identification of the QTLs related to ABA sensitivity and characterization of the ABA sensitive line YIL53 would provide a helpful basis for isolating novel genes related to ABA sensitivity.展开更多
QTLs for heading date located in the regions of Hd3a and Hd1 were detected using an F2:3 population developed from a residual heterozygous line(RHL) identified from the recombinant inbred lines of the indica rice cros...QTLs for heading date located in the regions of Hd3a and Hd1 were detected using an F2:3 population developed from a residual heterozygous line(RHL) identified from the recombinant inbred lines of the indica rice cross Zhenshan 97B /Milyang 46.Linkage in coupling phase between the QTLs for heading date and yield traits detected in a previous study was found.Four more F2:3 populations were each developed from an RHL that was homozygous at Hd3a and Hd1 but heterozygous in a portion of the intervals flanked by Hd3a and Hd1.QTLs for grain yield per plant,number of panicles per plant,number of grains per panicle and 1000-grain weight were detected in the heterozygous region.Five sets of near-isogenic lines(NILs) with overlapping heterogenous segments covering the interval RM6119-RM6779 were developed and used to validate and delimitate the QTLs.A QTL conferring a consistent effect for the number of grains per panicle was located within the interval RM19615-RM19652 that corresponded to a 514.4-kb region on chromosome 6.The same region might have pleiotropic effects on the other three yield-related traits analyzed,but the effects varied greatly among different populations and across different environments.This study suggests that it is possible to develop a population with little variation on heading date and to identify QTLs for yield traits that might not be associated with heading date by using the information of physical positions of DNA markers and cloned genes.展开更多
基金supported by the National Natural Science Foundation of China (31521064)the Chinese 863 Program (2014AA10A603)project of the China National Rice Research Institute (2014RG003-1)
文摘Grain size is a major determinant of grain weight and a trait having important impact on grain quality in rice. The objective of this study is to detect QTLs for grain size in rice and identify important QTLs that have not been well characterized before. The QTL mapping was first performed using three recombinant inbred line populations derived from indica rice crosses Teqing/IRBB lines, Zhenshan 97/Milyang 46, Xieqingzao/Milyang 46. Fourteen QTLs for grain length and 10 QTLs for grain width were detected, including seven shared by two populations and 17 found in one population. Three of the seven com- mon QTLs were found to coincide in position with those that have been cloned and the four others remained to be clarified. One of them, qGSIO located in the interval RM6100-RM228 on the long arm of chromosome 10, was validated using F2：3 populations and near isogenic lines derived from residual heterozygotes for the interval RM6100-RM228. The QTL was found to have a considerable effect on grain size and grain weight, and a small effect on grain number. This region was also previously detected for quality traits in rice in a number of studies, providing a good candidate for functional analysis and breeding utilization.
基金supported by the National Natural Science Foundation of China (Grant No. 31200916)the Zhejiang Provincial Project for Rice Seed Industry of Scientific and Technological Innovation Team (Grant No. 2010R50024-16)the Academy of Institute Foundation for Basic Scientific Research of China (Grant No. 2012RG002-7)
文摘A recombinant inbred line population derived from a super hybrid rice Xieyou 9308（Xieqingzao B/Zhonghui 9308） and its genetic linkage map were used to detect quantitative trait loci（QTLs） for rice yield traits under the low and normal nitrogen（N） levels. A total of 52 QTLs for yield traits distributed in 27 regions on 9 chromosomes were detected, with each QTL explaining 4.93%–26.73% of the phenotypic variation. Eleven QTLs were simultaneously detected under the two levels, and 30 different QTLs were detected under the two N levels, thereby suggesting that the genetic bases controlling rice growth under the low and normal N levels were different. QTLs for number of panicles per plant, number of spikelets per panicle, number of filled grains per panicle, and grain density per panicle under the two N levels were detected in the RM135–RM168 interval on chromosome 3. QTLs for number of spikelets per panicle and number of filled grains per panicle under the two N levels, as well as number of panicles per plant and grain density per panicle, under the low N level, were detected in the RM5556–RM310 interval on chromosome 8. The above described QTLs shared similar regions with previously reported QTLs for rice N recycling.
基金supported by the National Natural Science Foundation of China (31401377)the Science and Technology Project of Sichuan Province, China (2017JY0126)the Key Project of Education Department of Sichuan Province, China (14ZA0002)
文摘Organic phosphorus（P） is an important component of the soil P pool, and it has been proven to be a potential source of P for plants. The phosphorus utilization efficiency（PUE） and PUE related traits（tiller number（TN）, shoot dry weight（DW）, and root dry weight） under different phytate-P conditions（low phytate-P, 0.05 mmol L^-1 and normal phytate-P, 0.5 mmol L^-1） were investigated using a population consisting of 128 recombinant inbred lines（RILs） at the vegetative stage in barley. The population was derived from a cross between a P-inefficient genotype（Baudin） and a P-efficient genotype（CN4027, a Hordeum spontaneum accession）. A major locus（designated Qpue.sau-3 H） conferring PUE was detected in shoots and roots from the RIL population. The quantitative trait locus（QTL） was mapped on chromosome 3 H and the allele from CN4027 confers high PUE. This locus explained up to 30.3 and 28.4% of the phenotypic variance in shoots under low and normal phytate-P conditions, respectively. It also explains 28.3 and 30.7% of the phenotypic variation in root under the low and normal phytate-P conditions, respectively. Results from this study also showed that TN was not correlated with PUE, and a QTL controlling TN was detected on chromosome 5 H. However, dry weight（DW） was significantly and positively correlated with PUE, and a QTL controlling DW was detected near the Qpue.sau-3 H locus. Based on a covariance analysis, existing data indicated that, although DW may affect PUE, different genes at this locus are likely involved in controlling these two traits.
基金supported by the National Science Foundation of China (Grant No. 31221004)a research grant of the China National Rice Research Institute (Grant No. 2012RG002-3)
文摘1000-grain weight （ TGW） is one ot the three component traits ot the grain yiela in rice （Oryza sativa L）. This study was conducted to validate and fine-map qTGWl. 1, a minor QTL for TGW which was previously located in a 3.7-Mb region on the long arm of rice chromosome 1. Five sets of near isogenic lines （NILs） were developed from two BC2F4 populations of the indica rice cross Zhenshan 973/Milyang 46 The NIL sets consisted of two homozygous genotypic groups differing in the regions RM11448-RM11522, RM11448-RM11549, RM1232-RM11615, RM11543-RM11554 and RM11569-RM11621, respectively. Four traits, including TGW, grain length, grain width and heading date, were measured. Phenotypic difference between the two genotypic groups in each NIL population was analyzed using SAS procedure GLM. Significant QTL effects were detected on TGW with the Zhenshan 97 allele increasing grain weight by 0.12 g to 0.14 g and explaining 8.30% to 15.19% of the phenotypic variance. Significant effects were also observed for grain length and width, whereas no significant effect was found for heading date. Based on comparison among the five NILs on the segregating regions and the results of QTL analysis, qTGWl. 1 was delimited to a 376.9-kb region flanked by DNA markers Wn28382 and RMl1554. Our results indicate that the effects of minor QTLs could be steadily detected in a highly isogenic background and suggest that such QTLs could be utilized in the breeding of high-yielding rice varieties.
基金supported by the National Basic Research Program of China (973) (2009CB118401)the Hi-tech Research and Development Program of China (863)
文摘A thorough understanding of the quantitative trait loci （QTLs） that underlie agronomically important traits in crops would greatly increase agricultural productivity. Although advances have been made in QTL cloning, the majority of QTLs remain unknown because of their low heritability and minor contributions to phenotypic performance. Here we summarize the key advantages and disad- vantages of current QTL fine-mapping methodologies, and then introduce a sequential QTL fine-mapping strategy based on both genotypes and phenotypes of progeny derived from recombinants. With this mapping strategy, experimental errors could be dramat- ically diminished so as to reveal the authentic genetic effect of target QTLs. The number of progeny required to detect QTLs atvarious R2 values was calculated, and the backcross generation suitable to start QTL fine-mapping was also estimated. This mapping strategy has proved to be very powerful in narrowing down QTL regions, particularly minor-effect QTLs, as revealed by fine-mapping of various resistance QTLs in maize. Application of this sequential QTL mapping strategy should accelerate cloning of agronomically important QTLs, which is currently a substantial challenge in crops.
基金supported in part by the State Key Basic Research and Development Plan of China (2011CB100700 and 2009CB118306)National Transgenic Megaproject of China(2009ZX08009-053B and 2008ZX08009-001)the "One Hundred Talents" Foundation of the Chinese Academy of Sciences
文摘Stripe （yellow） rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks （Pst）, is one of the most important wheat （Triticum aestivum L.） diseases and causes significant yield losses. A recombinant inbred （RI） population derived from a cross between Yanzhan 1 and Xichang 76-9 cultivars was evaluated for resistance to wheat stripe rust strain CYR32 at both the seedling and adult plant stages. Four resistance quantitative trait loci （QTLs） were detected in this population, in which the major one, designated as Yrql, was mapped on chromosome 2DS. The strategy of using the Brachypodium distachyon genome, wheat expressed sequence tags and a draft DNA sequences （scaffolds） of the D-genome （Aegilops tauschfi Coss.） for the development of simple sequence repeat （SSR） markers was successfully used to identify 147 SSRs in hexaploid wheat. Of the 19 polymorphic SSRs in the RI population, 17 SSRs were mapped in the homeologous group 2 chromosomes near Yrql region and eight SSRs were genetically mapped in the 2.7 cM region of Yrql, providing abundant DNA markers for fine-mapping of Yrql and marker-assisted selection in wheat breeding program. The effectiveness of Yrql was validated in an independent population, indicating that this resistance QTL can be successfully transferred into a susceptible cultivar for improvement of stripe rust resistance.
基金supported by the National Hi-Tech Research and Development Program of China (2012AA101104-1)the National Natural Science Foundation of China (project no. 31200917)+1 种基金the Generation and Harvest Plus Challenge Program of CGIARthe Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences (CAAS)
文摘In this study, we considered five categories of molecular markers in clonal F1 and double cross populations, based on the number of distinguishable alleles and the number of distinguishable genotypes at the marker locus. Using the completed linkage maps, incomplete and missing markers were imputed as fully informative markers in order to simplify the linkage mapping approaches of quantitative trait genes. Under the condition of fully informative markers, we demonstrated that dominance effect between the female and male parents in clonal F1 and double cross populations can cause the interactions between markers. We then developed an inclusive linear model that includes marker variables and marker interactions so as to completely control additive effects of the female and male parents, as well as the dominance effect between the female and male parents. The linear model was finally used for background control in inclusive composite interval mapping （ICIM） of quantitative trait locus （QTL）. The efficiency of ICIM was demonstrated by extensive simulations and by comparisons with simple interval mapping, multiple-QTLmodels and composite interval mapping. Finally, ICIM was applied in one actual double cross population to identify QTL on days to silking in maize.
基金the Grant support from National Natural Science Foundation of China(U1706203,31172404 and 31572618)Taishan Scholar Project Fund of Shandong Province of China,and Youth Talent Program Supported by Laboratory for Marine Fisheries Science and Food Production Processes,Pilot National Laboratory for Marine Science and Technology(Qingdao)(2018-MFS-T07).
文摘The bay scallop and Peruvian scallop are economically important species.Interspecific hybrids of these two scallops outperformed both of their parent species in multiple growth traits but exhibited decreased fertility,which provides good models for the study of heterosis and species divergence.Genetic mapping serves as a chromosomal-level framework to investigate the molecular mechanisms of hybridization and introgression.In this study,high-resolution linkage maps were constructed for the bay and Peruvian scallops with an interspecific hybrid family.The linkage map of the bay scallop covered over 98.9% of the whole genome with 2994 mapped markers and the average marker interval of 0.32 cM.For the Peruvian scallop,1585 markers were mapped with the average maker interval of 0.51 cM,covering 97.7% of the genome.Both the two linkage maps have 16 linkage groups,corresponding to the haploid chromosome number of the two species.Approximately,54.5% of markers exhibited significant deviation from the expected Mendelian ratio of segregation,lending in sights into the intrinsic incompatibility between the two species.QTLs related to growth and shell coloration were detected,which could explain 13.1%and 74.9% of the phenotypic variance,respectively.This represents important information for further evaluation.These findings are an important addition to the genomic resources for scallop genetic studies,and are especially useful for investigations on genomic incompatibility for hybridization,genome evolution of closely related species,and genetic enhancement programs in aquaculture.
基金This work was supported by the China Scholarship Council[Grant Number 201906140047]National Natural Science Foundation of China[Grant Numbers 11801210,11801359 and 11771145].
文摘In this paper,we propose generalized fiducial methods and construct four generalized p-values to test the existence of quantitative trait locus effects under phenotype distributions from a location-scale family.Compared with the likelihood ratio test based on simulation studies,our methods perform better at controlling type I errors while retaining comparable power in cases with small or moderate sample sizes.The four generalized fiducial methods support varied sce-narios:two of them are more aggressive and powerful,whereas the other two appear more conservative and robust.A real data example involving mouse blood pressure is used to illustrate our proposed methods.
文摘Rice (Oryza sativa L.) eating and cooking quality is mainly influenced by its starch properties. Mapping quantitative trait loci (QTL) for starch properties not only helps us understand their genetic basis leading to acceleration of quality improvement, but also helps us find possible genes participating in the synthesis of starch. A recombinant inbred line (RIL) population consisting of 107 lines, derived from an indica (Zaiyeqing 8, ZYQ 8) and a japonica (Jingxi 17, JX 17) rice, was used to investigate the genetic factors affecting starch quality parameters, such as apparent amylose content (AAC), gel consistency (GC), starch pasting viscosity parameters, gel textural properties, gelatinization temperature (GT) and starch retrogradation properties. A total of 44 QTLs covered chromosomes 2-6, 8, 9 and 11 were detected for the 22 traits, with at least one QTL and as many as four QTLs for each individual trait. The results indicated that two major genes were responsible for most starch property traits. The Wx gene that encodes granule bound starch synthase on chromosome 6 was significant for AAC, GC, starch pasting viscosity parameters, gel textural properties and starch retrogradation properties. The alk gene linked with Wx on chromosome 6 was significant for starch gelatinization temperature characteristics. All other QTLs were minor genes. One QTL on chromosome 9 flanked by RZ404 and G295 was significant for gel hardness (HD), gumminess (GUM), chewiness (CHEW), peak temperature of retrogradated starch (RTp), and percentage retrogradation (R%) and all these traits were not tested before.
基金supported by the National 863 Program of China (2011AA10A101)the Chinese High-Yielding Transgenic Program (2011ZX08001-004)a project of the State Key Laboratory of Rice Biology,China(ZZKT201101)
文摘Quantitative trait loci（QTL） for percentage of chalky grain,degree of chalkiness,and endosperm transparency were detected using 3 recombinant inbred line populations derived from crosses between parental lines of commercial three-line hybrids of indica rice.Two of the populations showed great variations on heading date,and the other had a short range of heading date variation.A total of 40 QTLs were detected and fell into 15 regions of 10 chromosomes,of which 5 regions were detected for 1 or more same traits over different populations,2 were detected for different traits in different populations,3 were detected for 2 or all the 3 traits in a single population,and 5 were detected for a single trait in a single population.Most of these QTLs have been reported previously,but a region located on the long arm of chromosome 10 showing significant effects in all the 3 populations has not been reported before.It was shown that a number of gene cloned,including the Wx and Alk for the physiochemical property of rice grain,and GW2,GS3 and GW5 for grain weight and grain size,could have played important roles for the genetic control of grain chalkiness in rice,but there are many more QTLs exerting stable effects for rice chalkiness over different genetic backgrounds.It is worth paying more attentions to these regions which harbor QTL such as the qPCG5.2/qDC5.2/qET5.2 and qPCG10/qDC10/qET10 detected in our study.Our results also showed that the use of segregating populations having high-uniform heading date could greatly increase the efficiency of the identification of QTL responsible for traits that are subjected to great environmental influence.
文摘The quantitative trait loci （QTLs） for the dead leaf rate （DLR） and the dead seedling rate （DSR） at the different rice growing periods after transplanting under alkaline stress were identified using an F2：3 population, which included 200 individuals and lines derived from a cross between two japonica rice cultivars Gaochan 106 and Changbai 9 with microsatellite markers. The DLR detected at 20 days to 62 days after transplanting under alkaline stress showed continuous normal or near normal distributions in F3 lines, which was the quantitative trait controlled by multiple genes. The DSR showed a continuous distribution with 3 or 4 peaks and was the quantitative trait controlled by main and multiple genes when rice was grown for 62 days after transplanting under alkaline stress. Thirteen QTLs associated with DLR were detected at 20 days to 62 days after transplanting under alkaline stress. Among these, qDLR9-2 located in RM5786-RM160 on chromosome 9 was detected at 34 days, 41 days, 48 days, 55 days, and 62 days, respectively; qDLR4 located in RM3524-RM3866 on chromosome 4 was detected at 34 days, 41 days, and 48 days, respectively; qDLR7-1 located in RM3859-RM320 on chromosome 7 was detected at 20 days and 27 days; and qDLR6-2 in RM1340-RM5957 on chromosome 6 was detected at 55 days and 62 days, respectively. The alleles of both qDLR9-2 and qDLR4 were derived from alkaline sensitive parent ＂Gaochanl06＂. The alleles of both qDLR7-1 and qDLR6-2 were from alkaline tolerant parent Changbai 9. These gene actions showed dominance and over dominance primarily. Six QTLs associated with DSR were detected at 62 days after transplanting under alkaline stress. Among these, qDSR6-2 and qDSR8 were located in RM1340-RM5957 on chromosome 6 and in RM3752-RM404 on chromosome 8, respectively, which were associated with DSR and accounted for 20.32% and 18.86% of the observed phenotypic variation, respectively; qDSR11-2 and qDSR11-3 were located in RM536-RM479 and RM2596-RM286 on chromosome 11, respectively, which were associated with DSR explaining 25.85% and 15.41% of the observed phenotypic variation, respectively. The marker flanking distances of these QTLs were quite far except that of qDSR6-2, which should be researched further.
基金supported by the National Natural Science Foundation of China (Grant Nos. 30971745 and 30900874)the Natural Science Foundation of Hunan Province, China (Grant No. 08JJ1003)+1 种基金the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20070537006)the Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 06B042)
文摘High temperature stress (HTS), an increasingly important problem in rice production, significantly reduces rice yield by reducing pollen fertility and seed setting rate. Breeding rice varieties with tolerance to HTS at the flowering stage is therefore essential for maintaining rice production as the climate continues to become warm. In this study, two quantitative trait loci (QTLs) underlying tolerance to HTS were identified using recombinant inbred lines derived from a cross between an HTS-tolerant rice cultivar 996 and a sensitive cultivar 4628. Pollen fertility was used as a heat-tolerance indicator for the lines subjected to HTS at the flowering stage in field experiments. Two QTLs that affected pollen fertility, qPF4 and qPF6, were detected between RM5687 and RM471 on chromosome 4, and between RM190 and RM225 on chromosome 6, by using the composite interval mapping (CIM) analysis. The two QTLs explained 15.1% and 9.31% of the total phenotypic variation in pollen fertility, and increased the pollen fertility of the plants subjected to HTS by 7.15% and 5.25%, respectively. The positive additive effects of the two QTLs were derived from the 996 alleles. The two major QTLs identified would be useful for further fine mapping and cloning of these genes and for molecular marker-assistant breeding of heat-tolerant rice varieties.
基金supported by the National Key Technologies R&D Program of China (2006BAD13B01)the National Basic Research Program of China(2005DKA21001-01)the National Crop Resources Protect Program of China [NB06-070401(22-27)-01]
文摘Quantitative trait loci（QTLs） of grain traits were detected to provide theoretical basis for fine mapping and molecular marker-assisted breeding of grain traits in japonica rice.Using an F2 population including 200 individuals derived from a cross combination between two japonica rice DL115 with large grain and XL005 with small grain,the grain length,grain width,grain thickness,ratio of grain length to width and 1 000-grain weight were evaluated in Beijing;and the quantitative trait loci for above five grain traits were identified by composite interval mapping using SSR markers.The results showed that the five grain traits exhibited a normal continuous distribution in F2 population,indicating they were quantitative traits controlled by multiple genes.A total of 16 QTLs conferring the five grain traits were detected on chromosomes 2,3,5 and 12,respectively.Eight QTLs,namely qGL3a,qGW2,qGW5,qGT2,qRLW2,qRLW3,qGWT2 and qGWT3,were major QTLs and explained 15.42,40.89,13.54,33.43,13.82,13.61,12.51 and 10.1% of the observed phenotypic variance,respectively.Among them,qGW2,qGT2,qRLW2 and qGWT2 were mapped in same interval RM12776-RM324 on chromosome 2.The marker interval RM12776-RM324 on chromosome 2 was common marker intervals of four major QTLs,and the two SSR markers RM12776 and RM324 would be used in molecular markerassisted breeding in japonica rice.The modes of gene action were mainly additive and partial dominance.Four QTLs＇ alleles were derived from small grain parent XL005,and other 12 QTLs＇ alleles were derived from large grain parent DL115.The alleles from larger parent were showed significant effects to grain length,grain width,grain thickness and 1 000-grain weight.
基金funded by the Chinese High-Yielding Transgenic Program (Grant No. 2011ZX08001-004)the National High-Tech Research and Development Program (Grant No. 2011AA10A101)the Research Funding of China National Rice Research Institute(Grant No. 2009RG002)
文摘Grain yield and heading date are key factors determining the commercial potential of a rice variety. Mapping of quantitative trait loci （QTLs） in rice has been advanced from primary mapping to gene cloning, and heading date and yield traits have always attracted the greatest attention. In this review, genomic distribution of QTLs for heading date detected in populations derived from intra-specific crosses of Asian cultivated rice （Oryza sativa） was summarized, and their relationship with the genetic control of yield traits was analyzed. The information could be useful in the identification of QTLs for heading date and yield traits that are promising for the improvement of rice varieties.
基金supported in part by a Grant-in-Aid from the Ministry of Agriculture,Forestry and Fisheries,Japan(Genomics for Agricultural Innovation,QTL-4009)
文摘Seed dormancy contributes resistance to pre-harvest sprouting. Effects on respective quantitative trait loci （QTLs） for dormancy should be assessed by using fresh seeds before germinability altered through storage. We investigated QTLs related to seed dormancy using backcross inbred lines derived from a cross between Nipponbare and Kasalath. Four putative QTLs for seed dormancy were detected immediately after harvest using composite interval mapping. These putative QTLs were mapped near C1488 on chromosome 3 （qSD-3.1）, R2171 on chromosome 6 （qSD-6.1）, R1245 on chromosome 7 （qSD-7.1） and C488 on chromosome 10 （qSD-IO.1）. Kasalath alleles promoted dormancy for qSD-3.1, qSD-6.1 and qSD-7.1, and the respective proportions of phenotypic variation explained by each QTL were 12.9%, 9.3% and 8.1%. We evaluated the seed dormancy harvested at different ripening stages during seed development using chromosome segment substitution lines （CSSLs） to confirm gene effects. The germination rates of CSSL27 and CSSL28 substituted with the region including qSD-6.1 were significantly lower than those of Nipponbare and other CSSLs at the late ripening stage. Therefore, qSD-6.1 is considered the most effective novel QTL for pre-harvest sprouting resistance among the QTLs detected in this study.
基金funded by the National Natural Science Foundation of China(Grant No.30771330)the National Natural Science Foundation of Zhejiang Province,China(Grant No.Z306300)the Zhejiang Normal University Innovative Research Team Program of China
文摘Mercury （Hg） is one of the most toxic heavy metals to living organisms and its conspicuous effect is the inhibition of root growth. However, little is known about the molecular genetic basis for root growth under excess Hg2＋ stress. To map quantitative trait loci （QTLs） in rice for Hg2＋ tolerance, a population of 120 recombinant inbred lines derived from a cross between two japonica cultivars Yuefu and IRAT109 was grown in 0.5 mmol/L CaCI2 solution. Relative root length （RRL）, percentage of the seminal root length in ＋HgCI2 to -HgCI2, was used for assessing Hg2＋ tolerance. In a dose-response experiment, Yuefu had a higher RRL than IRAT109 and showed the most significant difference at the Hg2＋ concentration of 1.5 tJmol/L. Three putative QTLs for RRL were detected on chromosomes 1, 2 and 5, and totally explained about 35.7% of the phenotypic variance in Hg2＋ tolerance. The identified QTLs for RRL might be useful for improving Hg2＋ tolerance of rice by molecular marker-assisted selection.
基金supported by the Chinese Super Rice Research Program(200906)the High-Yielding Transgenic Program,China(2008ZX08001-004)the National Natural Science Foundation of China(30571062)
文摘A rice residual heterozygous line （RHL） carrying a heterozygous segment extending from RM111 to RM19784 on the short arm of rice chromosome 6 was selected from a RHL-derived population used previously. The resultant F2：3 population was used to detect quantitative trait loci （QTLs） for three yield traits, the number of spikelets per panicle （NSP）, the number of grains per panicle （NGP） and grain yield per plant （GY）. Two QTLs for NSP, one QTL for NGP and one QTL for GY were detected, all of which were partially dominant and had the enhancing alleles from the maternal line Zhenshan 97B. Analysis based on the genotypic groups of the markers closely linked to the two QTLs for NSP indicated that they did not interact with each other. Two F2 populations and two near isogenic line （NIL） sets segregating in two sub-regions of interval RM111-RM19784 were developed. The two QTLs for NSP were validated, of which one had major effect and was co-segregated with heading date gene Hdl, and the other had smaller effect and was located in an upper region linked to Hdl. The two regions also showed significant effects on the number of filled grain and grain yield, although the effect on the number of filled grain was less consistent.
基金supported by the Project of Conservation and Utilization of Agro-wild Plants of the Ministry of Agriculture of Chinathe Special Fund for Agro-scientific Research in the Public Interest,China(201003021)
文摘Abscisic acid （ABA）, as one of the foremost signaling molecules in plants, is an important hormone which plays versatile functions in regulating developmental process and adaptive stress process. A set of introgression lines were previously generated via a backcrossing program using an elite indica cultivar rice Teqing （O. sativa L.） as recipient and an accession of Yuanjiang common wild rice （O. rufipogon Griff.） as donor. In this study, the previously developed introgression lines were evaluated for ABA sensitivity. Here we reported that a total of 14 quantitative trait loci （QTLs） associated with ABA sensitivity were identified. An ABA sensitive introgression line, YIL53, was identified and characterized. Physiological characterization, including chlorophyll content, malondialdehyde content, soluble sugar content, and stomata movement, demonstrated that YIL53 exhibited the characteristics associated with ABA sensitivity. Genotypic analysis revealed that YIL53 harbored one QTL related to ABA sensitivity, qASS1-2, which was located on chromosome 1 within one introgressed segment derived from the Yuanjiang common wild rice. Furthermore, the qASS1-2 was finally narrowed down to a 441-kb region between simple sequence repeats （SSR） marker RM212 and single nucleotide polymorphism （SNP） marker M3 using the segregation population derived from the cross between Teqing and YIL53, and three candidate genes associated with ABA sensitivity were identified using a strategy combined gene expression analysis with QTL mapping. Identification of the QTLs related to ABA sensitivity and characterization of the ABA sensitive line YIL53 would provide a helpful basis for isolating novel genes related to ABA sensitivity.
基金supported by the Chinese Super Rice Breeding Program(Grant No.200906)the National High Technology Research and Development Program(Grant No.2009AA101101)the Research Funding of the China National RiceResearch Institute(Grant No.2009RG002)
文摘QTLs for heading date located in the regions of Hd3a and Hd1 were detected using an F2:3 population developed from a residual heterozygous line(RHL) identified from the recombinant inbred lines of the indica rice cross Zhenshan 97B /Milyang 46.Linkage in coupling phase between the QTLs for heading date and yield traits detected in a previous study was found.Four more F2:3 populations were each developed from an RHL that was homozygous at Hd3a and Hd1 but heterozygous in a portion of the intervals flanked by Hd3a and Hd1.QTLs for grain yield per plant,number of panicles per plant,number of grains per panicle and 1000-grain weight were detected in the heterozygous region.Five sets of near-isogenic lines(NILs) with overlapping heterogenous segments covering the interval RM6119-RM6779 were developed and used to validate and delimitate the QTLs.A QTL conferring a consistent effect for the number of grains per panicle was located within the interval RM19615-RM19652 that corresponded to a 514.4-kb region on chromosome 6.The same region might have pleiotropic effects on the other three yield-related traits analyzed,but the effects varied greatly among different populations and across different environments.This study suggests that it is possible to develop a population with little variation on heading date and to identify QTLs for yield traits that might not be associated with heading date by using the information of physical positions of DNA markers and cloned genes.
