In maize,prolificacy,the number of ears per plant,is a trait of interest to maize breeders for breeding high grain-yielding cultivars or specialty corn,as well as being a model trait for decoding the molecular mechani...In maize,prolificacy,the number of ears per plant,is a trait of interest to maize breeders for breeding high grain-yielding cultivars or specialty corn,as well as being a model trait for decoding the molecular mechanism of maize evolution.Its genetic basis remains largely unknown.We identified a stable quantitative trait locus,qEN7,for ear number on chromosome 7 in both F2 and F2:3 populations derived from a single cross between the nonprolific inbred line Mo17 and the prolific inbred line LAN404 derived from the landrace PI217404.qEN7 explained 10.7%-11.9%of phenotypic variation,and the LAN404 allele at this locus was associated with an increase of around one ear per plant.qEN7 was confined by fine-mapping to a 0.56-Mb region containing eight annotated genes.Analysis of selection,gene expression patterns in various maize tissues,and sequence polymorphisms between the two parental lines suggested that Zm00001d020683,which encodes a putative INDETERMINATE DOMAIN(IDD)transcription factor,is the most likely candidate gene underlying qEN7.Zm00001d020683 is expressed mainly in the vegetative meristem,immature ears,and internodes and has undergone selection during maize improvement.The identification of qEN7 and the prediction of its candidate gene sheds some light on the evolution of maize ear number and provides a novel resource for breeding of multi-ear maize cultivars.展开更多
Potassium(K) is an essential macronutrient for plant growth and development and influences yield and quality of agricultural crops.Maize(Zea mays) is one of the most widely distributed crops worldwide.In China,althoug...Potassium(K) is an essential macronutrient for plant growth and development and influences yield and quality of agricultural crops.Maize(Zea mays) is one of the most widely distributed crops worldwide.In China,although maize consumes a large amount of K fertilizer,the K uptake/utilization efficiency(KUE)of maize cultivars is relatively low.Elucidation of KUE mechanisms and development of maize cultivars with higher KUE are needed.Maize KUE is determined by K+uptake,transport,and remobilization,which depend on a variety of K+channels and transporters.We review basic information about K+channels and transporters in maize,their functions and regulation,and the roles of K+in nitrogen transport,sugar transport,and salt tolerance.We discuss challenges and prospects for maize KUE improvement.展开更多
Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamic...Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds.A maize DIR,ZmDRR206,was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development.Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity(CWI)maintenance.Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection.ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance,revealing a tradeoff between growth and defense.Consistently,ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis,while increasing the contents of major cell wall components,defense phytohormones,and defense metabolites,and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings.ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben,and ZmDRR206 physically interacted with ZmCesA10,which is a cellulose synthase unit.Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth,and might be exploited for breeding strong disease resistance in maize.展开更多
Stalk strength increases resistance to stalk lodging,which causes maize(Zea mays L.)production losses worldwide.The genetic mechanisms regulating stalk strength remain unclear.In this study,three stalk strength-relate...Stalk strength increases resistance to stalk lodging,which causes maize(Zea mays L.)production losses worldwide.The genetic mechanisms regulating stalk strength remain unclear.In this study,three stalk strength-related traits(rind penetrometer resistance,stalk crushing strength,and stalk bending strength)and four plant architecture traits(plant height,ear height,stem diameter,stem length)were measured in three field trials.Substantial phenotypic variation was detected for these traits.A genome-wide association study(GWAS)was conducted using general and mixed linear models and 372,331 single-nucleotide polymorphisms(SNPs).A total of 94 quantitative trait loci including 241 SNPs were detected.By combining the GWAS data with public gene expression data,56 candidate genes within 50 kb of the significant SNPs were identified,including genes encoding flavonol synthase(GRMZM2G069298,ZmFLS2),nitrate reductase(GRMZM5G878558,ZmNR2),glucose-1-phosphate adenylyltransferase(GRMZM2G027955),and laccase(GRMZM2G447271).Resequencing GRMZM2G069298 and GRMZM5G878558 in all tested lines revealed respectively 47 and 2 variants associated with RPR.Comparison of the RPR of the zmnr2EMS mutant and the wild-type plant under high-and low-nitrogen conditions verified the GRMZM5G878558 function.These findings may be useful for clarifying the genetic basis of stalk strength.The identified candidate genes and variants may be useful for the genetic improvement of maize lodging resistance.展开更多
Doubled haploid(DH)technology is an important tool in crop breeding because it can significantly accelerate the breeding process.ZmPLA1/MATL/NLD and ZmDMP are two key genes controlling haploid induction(HI)in maize,ex...Doubled haploid(DH)technology is an important tool in crop breeding because it can significantly accelerate the breeding process.ZmPLA1/MATL/NLD and ZmDMP are two key genes controlling haploid induction(HI)in maize,exhibiting a synergistic effect.However,it is unknown whether knock out of ZmDMP orthologs can stimulate HI in rice.In this study,a ZmPLA1 ortholog(OsPLA1)and two ZmDMP orthologs(OsDMP3 and OsDMP6)were identified in rice.All three genes encode plasma membrane-localized proteins and were highly expressed in mature anthers.Knockout of OsPLA1 in both Minghui 63 and Nipponbare resulted in reduced seed setting rate(SSR)and caused HI.The osdmp3,osdmp6 and the double mutant failed to trigger HI independently,nor increased the haploid induction rate(HIR)when combined with ospla1.Repeated pollinations operations of QX654A with the ospla1 mutant significantly improve SSR,while reducing HIR.RNA-seq profiling of mature ospla1 mutant anthers indicated that a large number of differentially expressed genes(DEGs)were enriched in redox homeostasis and lipid metabolic GO terms,plant hormone signal transduction,and MAPK signaling pathways.These findings provide important insights towards construction of an efficient DH breeding technology and study of the molecular mechanism of HI in rice.展开更多
Oil, protein and starch are key chemical components of maize kernels. A population of 245 recombinant inbred lines(RILs) derived from a cross between a high-oil inbred line, By804, and a regular inbred line, B73, was ...Oil, protein and starch are key chemical components of maize kernels. A population of 245 recombinant inbred lines(RILs) derived from a cross between a high-oil inbred line, By804, and a regular inbred line, B73, was used to dissect the genetic interrelationships among oil, starch and protein content at the individual QTL level by unconditional and conditional QTL mapping. Combined phenotypic data over two years with a genetic linkage map constructed using 236 markers, nine, five and eight unconditional QTL were detected for oil, protein and starch content, respectively. Some QTL for oil, protein and starch content were clustered in the same genomic regions and the direction of their effects was consistent with the sign of their correlation. In conditional QTL mapping, 37(29/8) unconditional QTL were not detected or showed reduced effects, four QTL demonstrated similar effects under unconditional and conditional QTL mapping, and 17 additional QTL were identified by conditional QTL mapping. These results imply that there is a strong genetic relationship among oil, protein and starch content in maize kernels. The information generated in the present investigation could be helpful in marker-assisted breeding for maize varieties with desirable kernel quality traits.展开更多
Stalk related traits, comprising plant height (PH), ear height (EH), internode number (IN), average internode length (AIL), stalk diameter (SD), and ear height coefficient (EHC), are significantly correlated with yiel...Stalk related traits, comprising plant height (PH), ear height (EH), internode number (IN), average internode length (AIL), stalk diameter (SD), and ear height coefficient (EHC), are significantly correlated with yield, density tolerance, and lodging resistance in maize. To investigate the genetic basis for stalk related traits, a doubled haploid (DH) population derived from a cross between NX531 and NX110 were evauluated under two densities over 2 yr. The additive quantitative trait loci (QTLs), epistatic QTLs were detected using inclusive composite interval mapping and QTL-by-environment interaction were detected using mixed linear model. Differences between the two densities were significant for the six traits in the DH population. A linkage map that covered 1 721.19 cM with an average interval of 10.50 cM was constructed with 164 simple sequence repeat (SSR). Two, two, seven, six, two, and eight additive QTLs for PH, IN, AIL, EH, SD, and EHC, respectively. The extend of their contribution to penotypic variation ranged from 10.10 to 31.93%. Seven QTLs were indentified simultaneously under both densities. One pair, two pairs and one pair of epistatic effects were detected for AIL, SD and EHC, respectively. No epistatic effects were detected for PH, EH, and IN. Nineteen QTLs with environment interactions were detected and their contribution to phenotypic variation ranged from 0.43 to 1.89%. Some QTLs were stably detected under different environments or genetic backgrounds comparing with previous studies. These QTLs could be useful for genetic improvement of stalk related traits in maize breeding.展开更多
In this study,a linkage genetic map was constructed using a F2 population derived from a cross between a elite maize inbred,B73,and its progenitor,Teosinte(Z.mays ssp.mexicana),through 205 simple sequence repeat(SSR) ...In this study,a linkage genetic map was constructed using a F2 population derived from a cross between a elite maize inbred,B73,and its progenitor,Teosinte(Z.mays ssp.mexicana),through 205 simple sequence repeat(SSR) markers and one morphological marker.By Mapmaker 3.0,polymorphic markers were clustered into 10 groups,covering 10 chromosomes of maizexteosinte,with a total length of 2 002.4 cM and an average interval of 9.7 cM.Genotyping errors were detected using R/QTL(LOD=2.0) in 109 markers referring to 176 individuals,distributed across all 10 chromosomes with a ratio 1.2%.Projected error loci were re-run and 304 out of the 460 were confirmed as errors and replaced.A new linkage map was constructed,in which markers maintained the same order but the total map length decreased to 1 947.8 cM,with an average interval of 9.4 cM between markers.In total,25.2%(P<0.05) markers were identified to have segregation distortion,in which 34.6% deviated towards the pollination parent(B73),30.8% deviated towards Teosinte,32.7% deviated towards heterozygote and 1.9% deviated towards both parents.This map was also compared with published maizexteosinte and maize IBM map.展开更多
Heterosis has contributed greatly to yield in maize, but the nature of its contribution is not completely clear. In this study, two strategies using whole-genome oligonucleotide microarrays were employed to identify d...Heterosis has contributed greatly to yield in maize, but the nature of its contribution is not completely clear. In this study, two strategies using whole-genome oligonucleotide microarrays were employed to identify differentially expressed genes (DEGs) associated with heterosis and yield. The analysis revealed 1 838 heterosis-associated genes (HAGs), 265 yield- associated genes (YAGs), and 85 yield heterosis-associated genes (YHAGs). 37.1% of HAGs and 22.4% of YHAGs expressed additively. The remaining genes expressed non-additively, including those with high/low-parent dominance and over/under dominance, which were prevalent in this research. Pathway enrichment analysis and quantitative trait locus (QTL) co-mapping demonstrated that the metabolic pathways for energy and carbohydrates were the two main enriched pathways influencing heterosis and yield. Therefore, the DEGs participating in energy and carbohydrate metabolism were considered to contribute to heterosis and yield significantly. The investigation of potential groups of HAGs, YAGs, and YHAGs might provide valuable information for exploiting heterosis to improve yield in maize breeding. In addition, our results support the view that heterosis is contributed by multiple, complex molecular mechanisms.展开更多
The maize mutant gene Vestigial glume 1(Vg1) has been fine-mapped to a narrow region by map-based cloning and the candidate gene for Vg1 spanned 19.5 kb. Here we report Vg1 genomic fosmid library construction and scre...The maize mutant gene Vestigial glume 1(Vg1) has been fine-mapped to a narrow region by map-based cloning and the candidate gene for Vg1 spanned 19.5 kb. Here we report Vg1 genomic fosmid library construction and screening. The fosmid library of Vg1 consisted of574,000 clones with an average insert size of 36.4 kb, representing 7.9-fold coverage of the maize genome. Fosmid stability assays indicated that clones were stable during propagation in the fosmid system. Using Vg1 candidate gene-specific primers, a positive clone was successfully identified. This discovery will pave the way for identifying the function of Vg1 in maize development.展开更多
Transposable elements have been utilized as mutagens to create mutant libraries for functional genomics. Isolation of genomic seg-ments flanking the insertion Mutator (Mu) is a key step in insertion mutagenesis studie...Transposable elements have been utilized as mutagens to create mutant libraries for functional genomics. Isolation of genomic seg-ments flanking the insertion Mutator (Mu) is a key step in insertion mutagenesis studies. Herein, we adopted a modified AFLP method to identify and isolate Mu-flanking fragments from maize. The method consists of the following steps: 1) double-digestion of genomic DNA with Bgl II/Msp I and ligation of digested fragments to the Bgl II-and Msp I-adaptors; 2) enrichment of a subset of Bgl II/Msp I fragments followed by selective amplification of the Mu-flanking fragments; 3) simultaneous display of AFLP bands derived from the flanking re-gions for both insert and native Mu transposons; 4) identification and isolation of AFLP bands resulting from Mu insertions by comparing the banding profiles between Mu-induced mutants and their parental lines; and 5) confirmation of flanking fragments related to these Mu insertions. Using this approach, we have isolated flanking fragment(s) resulting from Mu insertion for every Mu-induced mutant, and one such fragment, M196-FF, is found to contain a partial sequence of the DNA topoisomerase I gene Top1. Moreover, the modified AFLP method including all restriction enzymes, adaptors and primers has been optimized in this study. The modified AFLP method has been proved to be simple and efficient in the isolation of Mu-flanking fragments and will find its usefulness in the functional genomics of maize.展开更多
Food shortages arise more frequently owing to unpredictable crop yield losses caused by biotic and abiotic stresses. With advances in molecular biology and marker technology, a new era of molecular breeding has emerge...Food shortages arise more frequently owing to unpredictable crop yield losses caused by biotic and abiotic stresses. With advances in molecular biology and marker technology, a new era of molecular breeding has emerged that has greatly accelerated the pace of plant breeding. High-throughput genotyping technology and phenotyping platforms have enabled large-scale marker-trait association analysis, such as genome-wide association studies, to precisely dissect the genetic architecture of plant traits. Large-scale mapping of agronomically important quantitative trait loci, gene cloning and characterization, mining of elite alleles/haplotypes, exploitation of natural variations, and genomic selection have paved the way towards genomics-assisted breeding(GAB). With the availability of more and more informative genomic datasets, GAB would become a promising technique to expedite the breeding cycle for crop improvement.展开更多
Head smut, caused by the fungal pathogen Sporisorium reilianum, poses a grave threat to maize(Zea mays) production worldwide. Here we report cytological and molecular evidence for maize resistance to head smut. During...Head smut, caused by the fungal pathogen Sporisorium reilianum, poses a grave threat to maize(Zea mays) production worldwide. Here we report cytological and molecular evidence for maize resistance to head smut. During early stages of root infection, S. reilianum mycelium was capable of penetrating the root epidermis of both resistant(Ji1037) and susceptible(HZ4) inbred lines. S. reilianum hyphae were observed in the root–stem junction at 6 days after inoculation. In an attempt to monitor hyphal spread within the maize plant,a highly specific and sensitive real-time PCR method was established to estimate the hyphal content in infected maize tissues. During the upward growth of endophytic S.reilianum, the extent of hyphal spread was markedly different between Ji1037 and HZ4. Very little or no pathogen was detected in aerial parts of Ji1037, whereas large amounts of pathogen accumulated in aboveground tissues, particularly inflorescences, of HZ4. Thus,maize resistance to S. reilianum was achieved mainly by inhibition of endophytic hyphal growth rather than by prevention of early-root penetration by the pathogen.展开更多
Genome-wide prediction is a promising approach to boost selection gain in hybrid breeding.Our main objective was to evaluate the potential and limits of genome-wide prediction to identify superior hybrid combinations ...Genome-wide prediction is a promising approach to boost selection gain in hybrid breeding.Our main objective was to evaluate the potential and limits of genome-wide prediction to identify superior hybrid combinations adapted to Northwest China.A total of 490 hybrids derived from crosses among 119 inbred lines from the Shaan A and Shaan B heterotic pattern were used for genome-wide prediction of ten agronomic traits.We tested eight different statistical prediction models considering additive(A)effects and in addition evaluated the impact of dominance(D)and epistasis(E)on the prediction ability.Employing five-fold cross validation,we show that the average prediction ability ranged from 0.386 to 0.794 across traits and models.Six parametric methods,i.e.ridge regression,LASSO,Elastic Net,Bayes B,Bayes C and reproducing kernel Hilbert space(RKHS)approach,displayed a very similar prediction ability for each trait and two non-parametric methods(random forest and support vector machine)had a higher prediction performance for the trait rind penetrometer resistance of the third internode above ground(RPR_TIAG).The models of A+D RKHS and A+D+E RKHS were slightly better for predicting traits with a relatively high non-additive variance.Integrating trait-specific markers into the A+D RKHS model improved the prediction ability of grain yield by 3%,from 0.528 to 0.558.Of all 6328 potential hybrids,selection of the top 44 hybrids would lead to a 6%increase in grain yield compared with Zhengdan 958,a commercially successful hybrid variety.In conclusion,our results substantiate the value of genome-wide prediction for hybrid breeding and suggest dozens of promising single crosses for developing high-yielding hybrids for Northwest China.展开更多
The phytohormone auxin plays a central role in coordinating plant growth and development.GH3 is one of the three gene families that respond rapidly during auxin stimulation.Here,we report the identification and charac...The phytohormone auxin plays a central role in coordinating plant growth and development.GH3 is one of the three gene families that respond rapidly during auxin stimulation.Here,we report the identification and characterization of the GH3 gene family in maize.A total of 12 GH3 genes were identified,which are not evenly distributed over the 10 maize chromosomes.Maize GH3 protein sequences share a conserved domain which occupies nearly the entire protein.Diversified c/'s-elements were found in promoters of maize GH3 genes.In this study,the 12 maize GH3 proteins were primarily classified into two phylogenetic groups,similar to the 13 rice GH3 proteins,while 9 of the 19 Arabidopsis GH3 proteins were observed in the third phylogenetic group.Microarray analysis showed that expression of maize GH3 genes is temporally and spatially modulated.Additionally,maize GH3 genes displayed variable changes at transcript level upon pathogen infection.Results presented here provide insight into the diversification and evolution of GH3 proteins,and lay a foundation for the functional characterization of these GH3 genes in future,especially for elucidating the mechanisms of GH3-mediated pathogenesis.展开更多
General combining abilities(GCAs) are very important in utilization of heterosis in maize breeding. However, its genetic basis is unclear. In the present study, a set of 118 doubled haploid(DH) lines were induced from...General combining abilities(GCAs) are very important in utilization of heterosis in maize breeding. However, its genetic basis is unclear. In the present study, a set of 118 doubled haploid(DH) lines were induced from F_1 generations produced from the cross between the inbred line Zheng 58 and the inbred line W499 belonging to the Reid subgroup. Using the Maize SNP50 Bead Chip, a high-density genetic map was constructed based on the DH population which included 1 147 bin markers with an average interval length of 2.00 cM. Meanwhile, the DH population was crossed with three testers including W16-5, HD568, and W556, which belong to the Sipingtou subgroup. The GCAs of the ear height(EH), the kernel moisture content(KMC), the kernel ratio(KR), and the yield per plant(YPP) were estimated using these hybrids in three environments. Combining the high-density genetic map and the GCAs, a total of 14 QTLs were detected for the GCAs of the four traits. Especially, one pleiotropic QTL was identified on chromosome 1 between the SNP SYN16067 and the SNP PZE-101169244 which was simultaneously associated with the GCAs of the EH, the KR, and the YPP. These QTLs pave the way for further dissecting the genetic architecture underlying GCAs of the traits, and they may be used to enhance GCAs of inbred lines under the fixed heterotic pattern Reid×Sipingtou in China through a marker-assisted selection approach.展开更多
Doubled haploid(DH) technology is important in modern maize breeding. Haploid inducers determine the efficiency of both haploid induction and identification. It has taken decades to improve the efficiency,haploid indu...Doubled haploid(DH) technology is important in modern maize breeding. Haploid inducers determine the efficiency of both haploid induction and identification. It has taken decades to improve the efficiency,haploid induction rate(HIR), from the ~2% of the ancestor haploid inducer, stock6, to the ~10% of modern haploid inducers. Improvement of kernel oil content(KOC) would further enhance haploid identification efficiency. Using molecular marker-assisted selection, in combine with the number of haploids per ear as phenotypic criterion, we developed a new high-oil haploid inducer line, CHOI4, with a mean HIR of 15.8%and mean KOC of 11%. High KOC of CHOI4 can achieve a mean accuracy greater than 90% in identification of haploids of different backgrounds, with reduced false discovery rates and false negative rates in comparison with the previous high-oil haploid inducer line, CHOI3. Comparison of phenotypic selection strategies suggested that the number of haploids per ear can be used as a phenotyping criterion during haploid inducer line development. CHOI4 could further increase the efficiency of large-scale DH breeding programs with lower cost.展开更多
Heterosis plays an important role in crop production and plant evolution.Although heterosis has been widely exploited by plant breeders,the underlying molecular mechanisms are not well understood.We analyzed gene expr...Heterosis plays an important role in crop production and plant evolution.Although heterosis has been widely exploited by plant breeders,the underlying molecular mechanisms are not well understood.We analyzed gene expression of the highly heterotic maize hybrid Zhengdan 958 and its parents,Zheng 58 and Chang 7-2 during spikelet and floscule differentiation using the GeneChip Maize Genome Array.Pairwise comparison among Zhengdan 958 and its parents at the two stages of immature ear development identfied 1 089 and 1 352 differentially expressed genes.Gene ontology(GO) functional analysis showed that these genes participate in many functional categories,and those encoding response to stress and transcription factor may play important roles in heterosis.Pathway analysis showed that the differentially expressed genes are involved in various metabolic processes,and those participating in lipid metabolism,signal transduction,transport,and catabolism may contribute to heterosis.A non-additive expression pattern was prevalent in genes that were differentially expressed between the hybrid and its parents during both spikelet and floscule differentiation.Because genes that are differentially expressed in a hybrid and its parents could underlie heterosis,nonadditive expression patterns might contribute to the manifestation of heterosis.展开更多
Association mapping has emerged as a new tool to elucidate complex quantitative trait loci in maize, but there are few reports about systematic association analysis for the specific SSR markers with agronomic traits o...Association mapping has emerged as a new tool to elucidate complex quantitative trait loci in maize, but there are few reports about systematic association analysis for the specific SSR markers with agronomic traits of interest in China. We investigated the morphological and genetic diversity and population structure for 76 maize recombinant inbred lines, and then association analysis were further performed between 48 simple sequence repeat loci and 17 morphological traits, consisting of nine ear-related traits and eight other traits. The 48 SSR markers were screened out and further classified into two groups including a group of loci in regions harboring reported quantitative trait loci that affect ear shape and a group of markers distributing on the whole genome randomly. The result indicated that the population of recombinant inbred lines was structured, showing five subpopulations. Our association results revealed that there were 82, 59, and 40 significant associations detected by K-test, logistic regression, and both analysis, respectively. When the 17 traits were considered separately, the significant associations between Q-SSRs and E-traits were raised to 27.8%, whereas the other groups of combinations ranged between 2.3 and 6.3%. As the proportion of significant associations is higher among the Q-SSR subset of markers and the subset of traits related to ear shape than those for all of the other combinations, we conclude that this approach is valid for establishing true positive marker-trait relationships. Our results also demonstrated that association mapping could complement and enhance previous QTL information for marker-assisted selection.展开更多
The glume is an organ of the maize spikelet and plays important roles in anther and kernel development.Vestigial glume1(Vg1)is a classic mutant associated with ligule and glume development.Here we report the phenotypi...The glume is an organ of the maize spikelet and plays important roles in anther and kernel development.Vestigial glume1(Vg1)is a classic mutant associated with ligule and glume development.Here we report the phenotypic characterization,fine mapping,and candidate gene analysis of the Vg1 mutant.Vg1 is a semi-dominant and pleiotropic gene,and also affects plant height,ear height,and tassel length.Vg1 ligule degeneration begins at the first leaf,and the Vg1 tassel and ear can be distinguished from those of wild-type plants when their lengths reach respectively 55 mm and 51 mm.Using a BC3 mapping population of 11,445 plants,we delimited the Vg1 functional site to an interval of 7.4 kb,flanked by the markers InDelLM and CRM6.A putative cyclopropane fatty-acid synthase gene(ZmCPA-FAS1)was hypothesized to underlie the mutant phenotype.We detected a Helitron insertion in the sixth intron of ZmCPAFAS1.Its presence caused abnormal alternative splicing of ZmCPA-FAS1 that conferred new characteristics on the Vg1 mutant.These findings are a basis for further discovery of the molecularmechanism underlying glume development and a potential guide formaize breeding of small-glume varieties,especially sweet corn breeding.展开更多
基金supported by the National Natural Science Foundation of China(91935302)the Beijing Outstanding Young Scientist Program(BJJWZYJH01201910019026)the Chinese Universities Scientific Fund(2022TC035).
文摘In maize,prolificacy,the number of ears per plant,is a trait of interest to maize breeders for breeding high grain-yielding cultivars or specialty corn,as well as being a model trait for decoding the molecular mechanism of maize evolution.Its genetic basis remains largely unknown.We identified a stable quantitative trait locus,qEN7,for ear number on chromosome 7 in both F2 and F2:3 populations derived from a single cross between the nonprolific inbred line Mo17 and the prolific inbred line LAN404 derived from the landrace PI217404.qEN7 explained 10.7%-11.9%of phenotypic variation,and the LAN404 allele at this locus was associated with an increase of around one ear per plant.qEN7 was confined by fine-mapping to a 0.56-Mb region containing eight annotated genes.Analysis of selection,gene expression patterns in various maize tissues,and sequence polymorphisms between the two parental lines suggested that Zm00001d020683,which encodes a putative INDETERMINATE DOMAIN(IDD)transcription factor,is the most likely candidate gene underlying qEN7.Zm00001d020683 is expressed mainly in the vegetative meristem,immature ears,and internodes and has undergone selection during maize improvement.The identification of qEN7 and the prediction of its candidate gene sheds some light on the evolution of maize ear number and provides a novel resource for breeding of multi-ear maize cultivars.
基金supported by the National Key Research and Development Program of China (2021YFF1000500)National Natural Science Foundation of China (32025004, 32161133014, and31921001)Beijing Outstanding University Discipline Program。
文摘Potassium(K) is an essential macronutrient for plant growth and development and influences yield and quality of agricultural crops.Maize(Zea mays) is one of the most widely distributed crops worldwide.In China,although maize consumes a large amount of K fertilizer,the K uptake/utilization efficiency(KUE)of maize cultivars is relatively low.Elucidation of KUE mechanisms and development of maize cultivars with higher KUE are needed.Maize KUE is determined by K+uptake,transport,and remobilization,which depend on a variety of K+channels and transporters.We review basic information about K+channels and transporters in maize,their functions and regulation,and the roles of K+in nitrogen transport,sugar transport,and salt tolerance.We discuss challenges and prospects for maize KUE improvement.
基金the Ministry of Agriculture and Rural Affairs of the People’s Republic of China(2018ZX0800917B)grant from Yunnan Provincial Science and Technology Department(202005AF150026).
文摘Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds.A maize DIR,ZmDRR206,was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development.Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity(CWI)maintenance.Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection.ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance,revealing a tradeoff between growth and defense.Consistently,ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis,while increasing the contents of major cell wall components,defense phytohormones,and defense metabolites,and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings.ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben,and ZmDRR206 physically interacted with ZmCesA10,which is a cellulose synthase unit.Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth,and might be exploited for breeding strong disease resistance in maize.
基金supported by the National Natural Science Foundation of China(31972487,31902101,32172009 and 32061143030)the Innovative Research Team of Universities in Jiangsu Province,the Science and Technology Development Plan Project of Henan Province(212102110152)+1 种基金the High-end Talent Project of Yangzhou Universitythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Stalk strength increases resistance to stalk lodging,which causes maize(Zea mays L.)production losses worldwide.The genetic mechanisms regulating stalk strength remain unclear.In this study,three stalk strength-related traits(rind penetrometer resistance,stalk crushing strength,and stalk bending strength)and four plant architecture traits(plant height,ear height,stem diameter,stem length)were measured in three field trials.Substantial phenotypic variation was detected for these traits.A genome-wide association study(GWAS)was conducted using general and mixed linear models and 372,331 single-nucleotide polymorphisms(SNPs).A total of 94 quantitative trait loci including 241 SNPs were detected.By combining the GWAS data with public gene expression data,56 candidate genes within 50 kb of the significant SNPs were identified,including genes encoding flavonol synthase(GRMZM2G069298,ZmFLS2),nitrate reductase(GRMZM5G878558,ZmNR2),glucose-1-phosphate adenylyltransferase(GRMZM2G027955),and laccase(GRMZM2G447271).Resequencing GRMZM2G069298 and GRMZM5G878558 in all tested lines revealed respectively 47 and 2 variants associated with RPR.Comparison of the RPR of the zmnr2EMS mutant and the wild-type plant under high-and low-nitrogen conditions verified the GRMZM5G878558 function.These findings may be useful for clarifying the genetic basis of stalk strength.The identified candidate genes and variants may be useful for the genetic improvement of maize lodging resistance.
基金This work was supported by the National Key Research and Development Program of China(2022YFD1200800)the China Agriculture Research System(CARS-02-05)+1 种基金Beijing Nova Program(2023067)Yunnan Province Science and Technology Department(202305AF150026).
文摘Doubled haploid(DH)technology is an important tool in crop breeding because it can significantly accelerate the breeding process.ZmPLA1/MATL/NLD and ZmDMP are two key genes controlling haploid induction(HI)in maize,exhibiting a synergistic effect.However,it is unknown whether knock out of ZmDMP orthologs can stimulate HI in rice.In this study,a ZmPLA1 ortholog(OsPLA1)and two ZmDMP orthologs(OsDMP3 and OsDMP6)were identified in rice.All three genes encode plasma membrane-localized proteins and were highly expressed in mature anthers.Knockout of OsPLA1 in both Minghui 63 and Nipponbare resulted in reduced seed setting rate(SSR)and caused HI.The osdmp3,osdmp6 and the double mutant failed to trigger HI independently,nor increased the haploid induction rate(HIR)when combined with ospla1.Repeated pollinations operations of QX654A with the ospla1 mutant significantly improve SSR,while reducing HIR.RNA-seq profiling of mature ospla1 mutant anthers indicated that a large number of differentially expressed genes(DEGs)were enriched in redox homeostasis and lipid metabolic GO terms,plant hormone signal transduction,and MAPK signaling pathways.These findings provide important insights towards construction of an efficient DH breeding technology and study of the molecular mechanism of HI in rice.
基金supported by the National High Technology Research Program of China (No. 2012AA101104)
文摘Oil, protein and starch are key chemical components of maize kernels. A population of 245 recombinant inbred lines(RILs) derived from a cross between a high-oil inbred line, By804, and a regular inbred line, B73, was used to dissect the genetic interrelationships among oil, starch and protein content at the individual QTL level by unconditional and conditional QTL mapping. Combined phenotypic data over two years with a genetic linkage map constructed using 236 markers, nine, five and eight unconditional QTL were detected for oil, protein and starch content, respectively. Some QTL for oil, protein and starch content were clustered in the same genomic regions and the direction of their effects was consistent with the sign of their correlation. In conditional QTL mapping, 37(29/8) unconditional QTL were not detected or showed reduced effects, four QTL demonstrated similar effects under unconditional and conditional QTL mapping, and 17 additional QTL were identified by conditional QTL mapping. These results imply that there is a strong genetic relationship among oil, protein and starch content in maize kernels. The information generated in the present investigation could be helpful in marker-assisted breeding for maize varieties with desirable kernel quality traits.
基金the support of the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2011BAD35B01)the National High-Tech R&D Program of China(2011AA10A103-3)
文摘Stalk related traits, comprising plant height (PH), ear height (EH), internode number (IN), average internode length (AIL), stalk diameter (SD), and ear height coefficient (EHC), are significantly correlated with yield, density tolerance, and lodging resistance in maize. To investigate the genetic basis for stalk related traits, a doubled haploid (DH) population derived from a cross between NX531 and NX110 were evauluated under two densities over 2 yr. The additive quantitative trait loci (QTLs), epistatic QTLs were detected using inclusive composite interval mapping and QTL-by-environment interaction were detected using mixed linear model. Differences between the two densities were significant for the six traits in the DH population. A linkage map that covered 1 721.19 cM with an average interval of 10.50 cM was constructed with 164 simple sequence repeat (SSR). Two, two, seven, six, two, and eight additive QTLs for PH, IN, AIL, EH, SD, and EHC, respectively. The extend of their contribution to penotypic variation ranged from 10.10 to 31.93%. Seven QTLs were indentified simultaneously under both densities. One pair, two pairs and one pair of epistatic effects were detected for AIL, SD and EHC, respectively. No epistatic effects were detected for PH, EH, and IN. Nineteen QTLs with environment interactions were detected and their contribution to phenotypic variation ranged from 0.43 to 1.89%. Some QTLs were stably detected under different environments or genetic backgrounds comparing with previous studies. These QTLs could be useful for genetic improvement of stalk related traits in maize breeding.
基金supported by the National High-Tech R&D Program of China(2006AA10Z183,2006AA10A107)
文摘In this study,a linkage genetic map was constructed using a F2 population derived from a cross between a elite maize inbred,B73,and its progenitor,Teosinte(Z.mays ssp.mexicana),through 205 simple sequence repeat(SSR) markers and one morphological marker.By Mapmaker 3.0,polymorphic markers were clustered into 10 groups,covering 10 chromosomes of maizexteosinte,with a total length of 2 002.4 cM and an average interval of 9.7 cM.Genotyping errors were detected using R/QTL(LOD=2.0) in 109 markers referring to 176 individuals,distributed across all 10 chromosomes with a ratio 1.2%.Projected error loci were re-run and 304 out of the 460 were confirmed as errors and replaced.A new linkage map was constructed,in which markers maintained the same order but the total map length decreased to 1 947.8 cM,with an average interval of 9.4 cM between markers.In total,25.2%(P<0.05) markers were identified to have segregation distortion,in which 34.6% deviated towards the pollination parent(B73),30.8% deviated towards Teosinte,32.7% deviated towards heterozygote and 1.9% deviated towards both parents.This map was also compared with published maizexteosinte and maize IBM map.
基金supported by the National Basic Research Program of China (2007CB109000 and 2009CB118400)
文摘Heterosis has contributed greatly to yield in maize, but the nature of its contribution is not completely clear. In this study, two strategies using whole-genome oligonucleotide microarrays were employed to identify differentially expressed genes (DEGs) associated with heterosis and yield. The analysis revealed 1 838 heterosis-associated genes (HAGs), 265 yield- associated genes (YAGs), and 85 yield heterosis-associated genes (YHAGs). 37.1% of HAGs and 22.4% of YHAGs expressed additively. The remaining genes expressed non-additively, including those with high/low-parent dominance and over/under dominance, which were prevalent in this research. Pathway enrichment analysis and quantitative trait locus (QTL) co-mapping demonstrated that the metabolic pathways for energy and carbohydrates were the two main enriched pathways influencing heterosis and yield. Therefore, the DEGs participating in energy and carbohydrate metabolism were considered to contribute to heterosis and yield significantly. The investigation of potential groups of HAGs, YAGs, and YHAGs might provide valuable information for exploiting heterosis to improve yield in maize breeding. In addition, our results support the view that heterosis is contributed by multiple, complex molecular mechanisms.
基金supported by a Chongqing Postdoctoral Science Foundation funded project (Xm201344)China Postdoctoral Science Foundation funded project (2014M552303)Fundamental Research Funds for the Central Universities (XDJK2013C023, 2362015xk05)
文摘The maize mutant gene Vestigial glume 1(Vg1) has been fine-mapped to a narrow region by map-based cloning and the candidate gene for Vg1 spanned 19.5 kb. Here we report Vg1 genomic fosmid library construction and screening. The fosmid library of Vg1 consisted of574,000 clones with an average insert size of 36.4 kb, representing 7.9-fold coverage of the maize genome. Fosmid stability assays indicated that clones were stable during propagation in the fosmid system. Using Vg1 candidate gene-specific primers, a positive clone was successfully identified. This discovery will pave the way for identifying the function of Vg1 in maize development.
文摘Transposable elements have been utilized as mutagens to create mutant libraries for functional genomics. Isolation of genomic seg-ments flanking the insertion Mutator (Mu) is a key step in insertion mutagenesis studies. Herein, we adopted a modified AFLP method to identify and isolate Mu-flanking fragments from maize. The method consists of the following steps: 1) double-digestion of genomic DNA with Bgl II/Msp I and ligation of digested fragments to the Bgl II-and Msp I-adaptors; 2) enrichment of a subset of Bgl II/Msp I fragments followed by selective amplification of the Mu-flanking fragments; 3) simultaneous display of AFLP bands derived from the flanking re-gions for both insert and native Mu transposons; 4) identification and isolation of AFLP bands resulting from Mu insertions by comparing the banding profiles between Mu-induced mutants and their parental lines; and 5) confirmation of flanking fragments related to these Mu insertions. Using this approach, we have isolated flanking fragment(s) resulting from Mu insertion for every Mu-induced mutant, and one such fragment, M196-FF, is found to contain a partial sequence of the DNA topoisomerase I gene Top1. Moreover, the modified AFLP method including all restriction enzymes, adaptors and primers has been optimized in this study. The modified AFLP method has been proved to be simple and efficient in the isolation of Mu-flanking fragments and will find its usefulness in the functional genomics of maize.
文摘Food shortages arise more frequently owing to unpredictable crop yield losses caused by biotic and abiotic stresses. With advances in molecular biology and marker technology, a new era of molecular breeding has emerged that has greatly accelerated the pace of plant breeding. High-throughput genotyping technology and phenotyping platforms have enabled large-scale marker-trait association analysis, such as genome-wide association studies, to precisely dissect the genetic architecture of plant traits. Large-scale mapping of agronomically important quantitative trait loci, gene cloning and characterization, mining of elite alleles/haplotypes, exploitation of natural variations, and genomic selection have paved the way towards genomics-assisted breeding(GAB). With the availability of more and more informative genomic datasets, GAB would become a promising technique to expedite the breeding cycle for crop improvement.
基金funded by the Ministry of Agriculture of China (2013ZX08009003-001-007)the National High Technology Research and Development Program of China (2012AA101104, 2012AA10A306)
文摘Head smut, caused by the fungal pathogen Sporisorium reilianum, poses a grave threat to maize(Zea mays) production worldwide. Here we report cytological and molecular evidence for maize resistance to head smut. During early stages of root infection, S. reilianum mycelium was capable of penetrating the root epidermis of both resistant(Ji1037) and susceptible(HZ4) inbred lines. S. reilianum hyphae were observed in the root–stem junction at 6 days after inoculation. In an attempt to monitor hyphal spread within the maize plant,a highly specific and sensitive real-time PCR method was established to estimate the hyphal content in infected maize tissues. During the upward growth of endophytic S.reilianum, the extent of hyphal spread was markedly different between Ji1037 and HZ4. Very little or no pathogen was detected in aerial parts of Ji1037, whereas large amounts of pathogen accumulated in aboveground tissues, particularly inflorescences, of HZ4. Thus,maize resistance to S. reilianum was achieved mainly by inhibition of endophytic hyphal growth rather than by prevention of early-root penetration by the pathogen.
基金This work was supported by the National Key Research and Development Program of China(2016YFD0101200 and 2018YFD0100200)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education.
文摘Genome-wide prediction is a promising approach to boost selection gain in hybrid breeding.Our main objective was to evaluate the potential and limits of genome-wide prediction to identify superior hybrid combinations adapted to Northwest China.A total of 490 hybrids derived from crosses among 119 inbred lines from the Shaan A and Shaan B heterotic pattern were used for genome-wide prediction of ten agronomic traits.We tested eight different statistical prediction models considering additive(A)effects and in addition evaluated the impact of dominance(D)and epistasis(E)on the prediction ability.Employing five-fold cross validation,we show that the average prediction ability ranged from 0.386 to 0.794 across traits and models.Six parametric methods,i.e.ridge regression,LASSO,Elastic Net,Bayes B,Bayes C and reproducing kernel Hilbert space(RKHS)approach,displayed a very similar prediction ability for each trait and two non-parametric methods(random forest and support vector machine)had a higher prediction performance for the trait rind penetrometer resistance of the third internode above ground(RPR_TIAG).The models of A+D RKHS and A+D+E RKHS were slightly better for predicting traits with a relatively high non-additive variance.Integrating trait-specific markers into the A+D RKHS model improved the prediction ability of grain yield by 3%,from 0.528 to 0.558.Of all 6328 potential hybrids,selection of the top 44 hybrids would lead to a 6%increase in grain yield compared with Zhengdan 958,a commercially successful hybrid variety.In conclusion,our results substantiate the value of genome-wide prediction for hybrid breeding and suggest dozens of promising single crosses for developing high-yielding hybrids for Northwest China.
基金financially supported by the National Natural Science Foundation of China (31371625)
文摘The phytohormone auxin plays a central role in coordinating plant growth and development.GH3 is one of the three gene families that respond rapidly during auxin stimulation.Here,we report the identification and characterization of the GH3 gene family in maize.A total of 12 GH3 genes were identified,which are not evenly distributed over the 10 maize chromosomes.Maize GH3 protein sequences share a conserved domain which occupies nearly the entire protein.Diversified c/'s-elements were found in promoters of maize GH3 genes.In this study,the 12 maize GH3 proteins were primarily classified into two phylogenetic groups,similar to the 13 rice GH3 proteins,while 9 of the 19 Arabidopsis GH3 proteins were observed in the third phylogenetic group.Microarray analysis showed that expression of maize GH3 genes is temporally and spatially modulated.Additionally,maize GH3 genes displayed variable changes at transcript level upon pathogen infection.Results presented here provide insight into the diversification and evolution of GH3 proteins,and lay a foundation for the functional characterization of these GH3 genes in future,especially for elucidating the mechanisms of GH3-mediated pathogenesis.
基金financially supported by the National Key Research and Development Plan of China(2016YFD0101200)
文摘General combining abilities(GCAs) are very important in utilization of heterosis in maize breeding. However, its genetic basis is unclear. In the present study, a set of 118 doubled haploid(DH) lines were induced from F_1 generations produced from the cross between the inbred line Zheng 58 and the inbred line W499 belonging to the Reid subgroup. Using the Maize SNP50 Bead Chip, a high-density genetic map was constructed based on the DH population which included 1 147 bin markers with an average interval length of 2.00 cM. Meanwhile, the DH population was crossed with three testers including W16-5, HD568, and W556, which belong to the Sipingtou subgroup. The GCAs of the ear height(EH), the kernel moisture content(KMC), the kernel ratio(KR), and the yield per plant(YPP) were estimated using these hybrids in three environments. Combining the high-density genetic map and the GCAs, a total of 14 QTLs were detected for the GCAs of the four traits. Especially, one pleiotropic QTL was identified on chromosome 1 between the SNP SYN16067 and the SNP PZE-101169244 which was simultaneously associated with the GCAs of the EH, the KR, and the YPP. These QTLs pave the way for further dissecting the genetic architecture underlying GCAs of the traits, and they may be used to enhance GCAs of inbred lines under the fixed heterotic pattern Reid×Sipingtou in China through a marker-assisted selection approach.
基金supported by the National Key Research and Development Program of China(2016YFD0101200)the China Agriculture Research System(CARS-02)+1 种基金2020 Research Program of Sanya Yazhou Bay Science and Technology City(SKJC-2020-02-03)the National Natural Science Foundation of China(91935303,32001554)。
文摘Doubled haploid(DH) technology is important in modern maize breeding. Haploid inducers determine the efficiency of both haploid induction and identification. It has taken decades to improve the efficiency,haploid induction rate(HIR), from the ~2% of the ancestor haploid inducer, stock6, to the ~10% of modern haploid inducers. Improvement of kernel oil content(KOC) would further enhance haploid identification efficiency. Using molecular marker-assisted selection, in combine with the number of haploids per ear as phenotypic criterion, we developed a new high-oil haploid inducer line, CHOI4, with a mean HIR of 15.8%and mean KOC of 11%. High KOC of CHOI4 can achieve a mean accuracy greater than 90% in identification of haploids of different backgrounds, with reduced false discovery rates and false negative rates in comparison with the previous high-oil haploid inducer line, CHOI3. Comparison of phenotypic selection strategies suggested that the number of haploids per ear can be used as a phenotyping criterion during haploid inducer line development. CHOI4 could further increase the efficiency of large-scale DH breeding programs with lower cost.
基金supported by the National High-Tech R&D Program of China (2011AA10A103)the National Basic Research Program of China (2009CB118400)
文摘Heterosis plays an important role in crop production and plant evolution.Although heterosis has been widely exploited by plant breeders,the underlying molecular mechanisms are not well understood.We analyzed gene expression of the highly heterotic maize hybrid Zhengdan 958 and its parents,Zheng 58 and Chang 7-2 during spikelet and floscule differentiation using the GeneChip Maize Genome Array.Pairwise comparison among Zhengdan 958 and its parents at the two stages of immature ear development identfied 1 089 and 1 352 differentially expressed genes.Gene ontology(GO) functional analysis showed that these genes participate in many functional categories,and those encoding response to stress and transcription factor may play important roles in heterosis.Pathway analysis showed that the differentially expressed genes are involved in various metabolic processes,and those participating in lipid metabolism,signal transduction,transport,and catabolism may contribute to heterosis.A non-additive expression pattern was prevalent in genes that were differentially expressed between the hybrid and its parents during both spikelet and floscule differentiation.Because genes that are differentially expressed in a hybrid and its parents could underlie heterosis,nonadditive expression patterns might contribute to the manifestation of heterosis.
基金supported by the National Key Technologies R&D Program of China during the 11th Five-Year Plan period of Hebei Province (06220108D-2)
文摘Association mapping has emerged as a new tool to elucidate complex quantitative trait loci in maize, but there are few reports about systematic association analysis for the specific SSR markers with agronomic traits of interest in China. We investigated the morphological and genetic diversity and population structure for 76 maize recombinant inbred lines, and then association analysis were further performed between 48 simple sequence repeat loci and 17 morphological traits, consisting of nine ear-related traits and eight other traits. The 48 SSR markers were screened out and further classified into two groups including a group of loci in regions harboring reported quantitative trait loci that affect ear shape and a group of markers distributing on the whole genome randomly. The result indicated that the population of recombinant inbred lines was structured, showing five subpopulations. Our association results revealed that there were 82, 59, and 40 significant associations detected by K-test, logistic regression, and both analysis, respectively. When the 17 traits were considered separately, the significant associations between Q-SSRs and E-traits were raised to 27.8%, whereas the other groups of combinations ranged between 2.3 and 6.3%. As the proportion of significant associations is higher among the Q-SSR subset of markers and the subset of traits related to ear shape than those for all of the other combinations, we conclude that this approach is valid for establishing true positive marker-trait relationships. Our results also demonstrated that association mapping could complement and enhance previous QTL information for marker-assisted selection.
基金supported by the Commercial Breeding Innovation of Sweet Glutinous Maize Varieties (cstc2016shms-ztzx80014)Fundamental Research Funds for the Central Universities (XDJK2018C052)the Major Project Research of Chongqing (cstc2016shms-ztzx80016, cstc2016shms-ztzx80017)
文摘The glume is an organ of the maize spikelet and plays important roles in anther and kernel development.Vestigial glume1(Vg1)is a classic mutant associated with ligule and glume development.Here we report the phenotypic characterization,fine mapping,and candidate gene analysis of the Vg1 mutant.Vg1 is a semi-dominant and pleiotropic gene,and also affects plant height,ear height,and tassel length.Vg1 ligule degeneration begins at the first leaf,and the Vg1 tassel and ear can be distinguished from those of wild-type plants when their lengths reach respectively 55 mm and 51 mm.Using a BC3 mapping population of 11,445 plants,we delimited the Vg1 functional site to an interval of 7.4 kb,flanked by the markers InDelLM and CRM6.A putative cyclopropane fatty-acid synthase gene(ZmCPA-FAS1)was hypothesized to underlie the mutant phenotype.We detected a Helitron insertion in the sixth intron of ZmCPAFAS1.Its presence caused abnormal alternative splicing of ZmCPA-FAS1 that conferred new characteristics on the Vg1 mutant.These findings are a basis for further discovery of the molecularmechanism underlying glume development and a potential guide formaize breeding of small-glume varieties,especially sweet corn breeding.
