Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to...Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to viruses;hence,this study aimed to engineer SMV resistance in soybean using this system.Specifically,multiple sgRNAs were designed to target positive-and/or negative-sense strands of the SMV HC-Pro gene.Subsequently,the corresponding CRISPR/CasRx vectors were constructed and transformed into soybeans.After inoculation with SMV,39.02%,35.77%,and 18.70%of T_(1)plants were confirmed to be highly resistant(HR),resistant(R),and mildly resistant(MR)to SMV,respectively,whereas only 6.50%were identified as susceptible(S).Additionally,qRT-PCR and DAS-ELISA showed that,both at 15 and 30 d post-inoculation(dpi),SMV accumulation significantly decreased or was even undetectable in HR and R plants,followed by MR and S plants.Additionally,the expression level of the CasRx gene varied in almost all T_(1)plants with different resistance level,both at 15 and 30 dpi.Furthermore,when SMV resistance was evaluated in the T_(2)generation,the results were similar to those recorded for the T_(1)generation.These findings provide new insights into the application of the CRISPR/CasRx system for soybean improvement and offer a promising alternative strategy for breeding for resistance to biotic stress that will contribute to the development of SMV-immune soybean germplasm to accelerate progress towards greater soybean crop productivity.展开更多
Carotenoid is a tetraterpene pigment beneficial for human health.Although the carotenoid biosynthesis pathway has been extensively studied in plants,relatively little is known about their regulation in sweet potato.Pr...Carotenoid is a tetraterpene pigment beneficial for human health.Although the carotenoid biosynthesis pathway has been extensively studied in plants,relatively little is known about their regulation in sweet potato.Previously,we conducted the transcriptome database of differentially expressed genes between the sweet potato(Ipomoea batatas)cultivar‘Weiduoli’and its high-carotenoid mutant‘HVB-3’.In this study,we selected one of these candidate genes,IbNAC29,for subsequent analyses.IbNAC29 belongs to the plant-specific NAC(NAM,ATAF1/2,and CUC2)transcription factor family.Relative IbNAC29 mRNA level in the HVB-3 storage roots was∼1.71-fold higher than Weiduoli.Additional experiments showed that the contents ofα-carotene,lutein,β-carotene,zeaxanthin,and capsanthin are obviously increased in the storage roots of transgenic sweet potato plants overexpressing IbNAC29.Moreover,the levels of carotenoid biosynthesis genes in transgenic plants were also up-regulated.Nevertheless,yeast one-hybrid assays indicated that IbNAC29 could not directly bind to the promoters of these carotenoid biosynthesis genes.Furthermore,the level of IbSGR1 was down-regulated,whose homologous genes in tomato can negatively regulate carotene accumulation.Yeast three-hybrid analysis revealed that the IbNAC29-IbMYB1R1-IbAITR5 could form a regulatory module.Yeast one-hybrid,electrophoretic mobility shift assay,quantitative PCR analysis of chromatin immunoprecipitation and dual-luciferase reporter assay showed that IbAITR5 directly binds to and inhibits the promoter activity of IbSGR1,up-regulating carotenoid biosynthesis gene IbPSY.Taken together,IbNAC29 is a potential candidate gene for the genetic improvement of nutritive value in sweet potato.展开更多
Sweetpotato(Ipomoea batatas(L.)Lam.)is a widely grown food crop especially in developing countries.Increasing storage-root yield and dry-matter content has been the main breeding objective of the crop,and DNA marker-a...Sweetpotato(Ipomoea batatas(L.)Lam.)is a widely grown food crop especially in developing countries.Increasing storage-root yield and dry-matter content has been the main breeding objective of the crop,and DNA marker-assisted breeding is needed for this purpose.In this study,using a mapping population of 500 F1 individuals from a cross between Xushu 18(female)and Xu 781(male),we constructed a highdensity genetic linkage map of sweetpotato using 601 simple-sequence repeat(SSR)primer pairs.The Xushu 18 map contained 90 linkage groups with 5547 SSR markers and spanned 18,263.5 cM,and the Xu 781 map contained 90 linkage groups with 4599 SSR markers and spanned 18,043.7 cM,representing the highest genome coverage yet reported for sweetpotato.We identified 33 QTL for storage-root yield and 16 QTL for dry-matter content,explaining respectively 6.5%–47.5%and 3.2%–18.9%of variation.These results provide a foundation for fine-mapping and cloning of QTL and for marker-assisted breeding in sweetpotato.展开更多
Simple sequence repeat(SSR) markers have been proved to be a very powerful tool for quantitative trait locus(QTL) mapping, marker-assisted selection and comparative genomics research in many crop species. However, a h...Simple sequence repeat(SSR) markers have been proved to be a very powerful tool for quantitative trait locus(QTL) mapping, marker-assisted selection and comparative genomics research in many crop species. However, a high-density SSR genetic linkage map is still lacking because there are only a few SSR markers available in sweet potato. In this study, a total of 2545 simple sequence repeat(SSR) primer pairs, including 1215 genomic SSR(gSSR) primer pairs and 1330 BES-SSR(bSSR) primer pairs designed from the genome sequence and BAC-end sequence of sweet potato, respectively, were screened with sweet potato cultivars Luoxushu 8 and Zhengshu 20 and their randomly sampled two F1 individuals and 571 of them generated polymorphic bands. The selected 571 polymorphic SSR primer pairs and 35 EST-based SSR(eSSR) primer pairs developed at our laboratory were used to genotype 240 F1 individuals derived from a cross between Luoxushu 8 and Zhengshu 20. A double pseudo-test-cross strategy was applied for linkage analysis. The Luoxushu 8 map included 90 linkage groups with 5057 SSR markers and covered 13,299.9 cM with a marker density of 2.6 cM, and the Zhengshu 20 map contained 90 linkage groups with 3009 SSR markers and covered 11,122.9 cM with a marker density of 3.7 cM. Fifteen homologous groups were identified in both parent maps. These are the first SSR linkage maps consisting of the complete 90 linkage groups and 15 homologous groups, which are consistent with the autohexaploid nature of sweetpotato, and are also the linkage maps with the highest SSR marker density reported to date.These results provide a basis for QTL mapping, marker-assisted breeding and comparative genomics research of sweet potato.展开更多
Sweet potato(Ipomoea batatas[L.]Lam.)is a crucial staple and bioenergy crop.Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands.Transcriptional processes regulate abiotic stress...Sweet potato(Ipomoea batatas[L.]Lam.)is a crucial staple and bioenergy crop.Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands.Transcriptional processes regulate abiotic stress responses,yet the molecular regulatory mechanisms in sweet potato remain unclear.In this study,a NAC(NAM,ATAF1/2,and CUC2)transcription factor,IbNAC087,was identified,which is commonly upregulated in salt-and drought-tolerant germplasms.Overexpression of IbNAC087 increased salt and drought tolerance by increasing jasmonic acid(JA)accumulation and activating reactive oxygen species(ROS)scavenging,whereas silencing this gene resulted in opposite phenotypes.JA-rich IbNAC087-OE(overexpression)plants exhibited more stomatal closure than wild-type(WT)and IbNAC087-Ri plants under NaCl,polyethylene glycol,and methyl jasmonate treatments.IbNAC087 functions as a nuclear transcriptional activator and directly activates the expression of the key JA biosynthesisrelated genes lipoxygenase(IbLOX)and allene oxide synthase(IbAOS).Moreover,IbNAC087 physically interacted with a RING-type E3 ubiquitin ligase NAC087-INTERACTING E3 LIGASE(IbNIEL),negatively regulating salt and drought tolerance in sweet potato.IbNIEL ubiquitinated IbNAC087 to promote 26S proteasome degradation,which weakened its activation on IbLOX and IbAOS.The findings provide insights into the mechanism underlying the IbNIEL-IbNAC087 module regulation of JA-dependent salt and drought response in sweet potato and provide candidate genes for improving abiotic stress tolerance in crops.展开更多
Grain size is an important agronomic trait affecting grain yield,but the underlying molecular mechanisms remain to be elucidated.Here,we isolated a dominant mutant,big grainy(bg3-D),which exhibits a remarkable increas...Grain size is an important agronomic trait affecting grain yield,but the underlying molecular mechanisms remain to be elucidated.Here,we isolated a dominant mutant,big grainy(bg3-D),which exhibits a remarkable increase of grain size caused by activation of the PURINE PERMEASE gene,OsPUP4.BC3/OSPUP4 is predominantly expressed in vascular tissues and is specifically suppressed by exogenous cytokinin application.Hormone profiling revealed that the distribution of different cytokinin forms,in roots and shoots of the bg3-D mutant,is altered.Quantitative reverse transcription-PCR(qRT-PCR)analysis indicated that expression of rice cytokinin type-A RESPONSE REGULATOR(OsRR)genes is enhanced in the roots of the bgj-D mutant.These results suggest that OSPUP4 might contribute to the long-distance transport of cytokinin,by reinforcing cytokinin loading into vascular bundle cells.Furthermore,plants overexpressing OsPUP7,the closest homolog of OsPUP4,also exhibited a similar phenotype to the bg3-D mutant.Interestingly,subcellular localization demonstrated that OSPUP4 was localized on the plasma membrane,whereas OSPUP7 was localized to the endoplasmic reticulum.Based on these findings,we propose that OSPUP4 and OSPUP7 function in a linear pathway to direct cytokinin cell-to-cell transport,affecting both its long-distance movement and local allocation.展开更多
The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post-transcription-...The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post-transcription- ally programming gene expression, in relation to photosynthetic traits. We focused on miR408, one of the most conserved plant miRNAs, and overexpressed it in parallel in Arabidopsis, tobacco, and rice. The transgenic plants all exhibited increased copper content in the chloroplast, elevated abundance of plastocyanin, and an induction of photosynthetic genes. By means of gas exchange and optical spectroscopy analyses, we showed that higher expression of miR408 leads to enhanced photosynthesis through improving efficiency of irradiation utilization and the capacity for carbon dioxide fixation. Consequently, miR408 hyper-accumulat- ing plants exhibited higher rate of vegetative growth. An enlargement of seed size was also observed in all three species overproducing miR408. Moreover, we conducted a 2-year-two-location field trial and observed miR408 overexpression in rice significantly increased yield, which was primarily attributed to an elevation in grain weight. Taken together, these results demonstrate that miR408 is a positive regulator of photosynthesis and that its genetic engineering is a promising route for enhancing photosynthetic performance and yield in diverse plants.展开更多
In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and ...In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and 3＇ splicing junctions that are distinct from conventional （U2/U12-type） splicing boundaries.By using the known SDR-containing sequences as probes,24 plant candidate genes involved in diverse functional pathways from both monocots and dicots that potentially possess SDR-mediated posttranscriptional processing were predicted in the GenBank database.The SDRs-mediated posttranscriptional processing events including cis-and trans-actions were experimentally detected in majority of the predicted candidates.Extensive sequence analysis demonstrates several types of SDR-associated splicing peculiarities including partial exon deletion,exon fragment repetition,exon fragment scrambling and trans-splicing that result in either loss of partial exon or unusual exonic sequence rearrangements within or between RNA molecules.In addition,we show that the paired presence of SDR is necessary but not sufficient in SDR-mediated splicing in transient expression and stable transformation systems.We also show prokaryote is incapable of SDR-mediated premRNA splicing.展开更多
Gibberellins （GAs） are essential phytohormones regulating many aspects of plant growth and development. Manipulation of GA status either by genetic alteration or by exogenous application of GA or GA biosynthesis inh...Gibberellins （GAs） are essential phytohormones regulating many aspects of plant growth and development. Manipulation of GA status either by genetic alteration or by exogenous application of GA or GA biosynthesis inhibitors are common strategies used to optimize plant growth and crop yields. Rice （Oryza sativa） is a major source of calories and mineral nutrients, feeding more than half of the human population. With the challenges of feeding an increasing population and decreasing availability of arable land, improving productivity and yields of rice crop has always been an ultimate goal for breeders.展开更多
基金supported by grants from National Natural Science Foundation of China(32001571)R&D Program of Beijing Municipal Education Commission(KM202212448003,KM202312448004)+4 种基金Science and Technology Innovation Project of Beijing Vocational College of Agriculture(XY-YF-22-02)Zhongshan Biological Breeding Laboratory(ZSBBL-KY2023-03)China Agriculture Research System of MOF and MARA(CARS-04)Jiangsu Collaborative Innovation Center for Modern Crop Production(JCICMCP)Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry(CIC-MCP).
文摘Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to viruses;hence,this study aimed to engineer SMV resistance in soybean using this system.Specifically,multiple sgRNAs were designed to target positive-and/or negative-sense strands of the SMV HC-Pro gene.Subsequently,the corresponding CRISPR/CasRx vectors were constructed and transformed into soybeans.After inoculation with SMV,39.02%,35.77%,and 18.70%of T_(1)plants were confirmed to be highly resistant(HR),resistant(R),and mildly resistant(MR)to SMV,respectively,whereas only 6.50%were identified as susceptible(S).Additionally,qRT-PCR and DAS-ELISA showed that,both at 15 and 30 d post-inoculation(dpi),SMV accumulation significantly decreased or was even undetectable in HR and R plants,followed by MR and S plants.Additionally,the expression level of the CasRx gene varied in almost all T_(1)plants with different resistance level,both at 15 and 30 dpi.Furthermore,when SMV resistance was evaluated in the T_(2)generation,the results were similar to those recorded for the T_(1)generation.These findings provide new insights into the application of the CRISPR/CasRx system for soybean improvement and offer a promising alternative strategy for breeding for resistance to biotic stress that will contribute to the development of SMV-immune soybean germplasm to accelerate progress towards greater soybean crop productivity.
基金supported by the National Natural Science Foundation of China(31872878)the earmarked fund for CARS-10-Sweetpotato.
文摘Carotenoid is a tetraterpene pigment beneficial for human health.Although the carotenoid biosynthesis pathway has been extensively studied in plants,relatively little is known about their regulation in sweet potato.Previously,we conducted the transcriptome database of differentially expressed genes between the sweet potato(Ipomoea batatas)cultivar‘Weiduoli’and its high-carotenoid mutant‘HVB-3’.In this study,we selected one of these candidate genes,IbNAC29,for subsequent analyses.IbNAC29 belongs to the plant-specific NAC(NAM,ATAF1/2,and CUC2)transcription factor family.Relative IbNAC29 mRNA level in the HVB-3 storage roots was∼1.71-fold higher than Weiduoli.Additional experiments showed that the contents ofα-carotene,lutein,β-carotene,zeaxanthin,and capsanthin are obviously increased in the storage roots of transgenic sweet potato plants overexpressing IbNAC29.Moreover,the levels of carotenoid biosynthesis genes in transgenic plants were also up-regulated.Nevertheless,yeast one-hybrid assays indicated that IbNAC29 could not directly bind to the promoters of these carotenoid biosynthesis genes.Furthermore,the level of IbSGR1 was down-regulated,whose homologous genes in tomato can negatively regulate carotene accumulation.Yeast three-hybrid analysis revealed that the IbNAC29-IbMYB1R1-IbAITR5 could form a regulatory module.Yeast one-hybrid,electrophoretic mobility shift assay,quantitative PCR analysis of chromatin immunoprecipitation and dual-luciferase reporter assay showed that IbAITR5 directly binds to and inhibits the promoter activity of IbSGR1,up-regulating carotenoid biosynthesis gene IbPSY.Taken together,IbNAC29 is a potential candidate gene for the genetic improvement of nutritive value in sweet potato.
基金supported by the National Key Research and Development Program of China(2019YFD1001300,2019YFD1001301)the Earmarked Fund for CARS-10-Sweetpotato(CARS-10)+1 种基金the Beijing Food Crops Innovation Consortium Program(BAIC02-2022)Hebei Key R&D Program(20326320D,22322911D)。
文摘Sweetpotato(Ipomoea batatas(L.)Lam.)is a widely grown food crop especially in developing countries.Increasing storage-root yield and dry-matter content has been the main breeding objective of the crop,and DNA marker-assisted breeding is needed for this purpose.In this study,using a mapping population of 500 F1 individuals from a cross between Xushu 18(female)and Xu 781(male),we constructed a highdensity genetic linkage map of sweetpotato using 601 simple-sequence repeat(SSR)primer pairs.The Xushu 18 map contained 90 linkage groups with 5547 SSR markers and spanned 18,263.5 cM,and the Xu 781 map contained 90 linkage groups with 4599 SSR markers and spanned 18,043.7 cM,representing the highest genome coverage yet reported for sweetpotato.We identified 33 QTL for storage-root yield and 16 QTL for dry-matter content,explaining respectively 6.5%–47.5%and 3.2%–18.9%of variation.These results provide a foundation for fine-mapping and cloning of QTL and for marker-assisted breeding in sweetpotato.
基金supported by the National Key Research and Development Program of China (2018YFD1000706/2018YFD1000700)China Agriculture Research System (CARS-10, Sweet potato)。
文摘Simple sequence repeat(SSR) markers have been proved to be a very powerful tool for quantitative trait locus(QTL) mapping, marker-assisted selection and comparative genomics research in many crop species. However, a high-density SSR genetic linkage map is still lacking because there are only a few SSR markers available in sweet potato. In this study, a total of 2545 simple sequence repeat(SSR) primer pairs, including 1215 genomic SSR(gSSR) primer pairs and 1330 BES-SSR(bSSR) primer pairs designed from the genome sequence and BAC-end sequence of sweet potato, respectively, were screened with sweet potato cultivars Luoxushu 8 and Zhengshu 20 and their randomly sampled two F1 individuals and 571 of them generated polymorphic bands. The selected 571 polymorphic SSR primer pairs and 35 EST-based SSR(eSSR) primer pairs developed at our laboratory were used to genotype 240 F1 individuals derived from a cross between Luoxushu 8 and Zhengshu 20. A double pseudo-test-cross strategy was applied for linkage analysis. The Luoxushu 8 map included 90 linkage groups with 5057 SSR markers and covered 13,299.9 cM with a marker density of 2.6 cM, and the Zhengshu 20 map contained 90 linkage groups with 3009 SSR markers and covered 11,122.9 cM with a marker density of 3.7 cM. Fifteen homologous groups were identified in both parent maps. These are the first SSR linkage maps consisting of the complete 90 linkage groups and 15 homologous groups, which are consistent with the autohexaploid nature of sweetpotato, and are also the linkage maps with the highest SSR marker density reported to date.These results provide a basis for QTL mapping, marker-assisted breeding and comparative genomics research of sweet potato.
基金supported by the National Key R&D Program of China(2023YFD1200700/2023YFD1200702)the Beijing Natural Science Foundation(grant no.6212017)+3 种基金the Beijing Food Crops Innovation Consortium Program(BAIC02-2023)the Project of Sanya Yazhou Bay Science and Technology City(grant no.SCKJ-JYRC-2022-61/SYND-2022-09)China Agriculture Research System of MOF and MARA(CARS-10,Sweetpotato)Chinese Universities Scientific Fund(2023TC057/2022TC003)。
文摘Sweet potato(Ipomoea batatas[L.]Lam.)is a crucial staple and bioenergy crop.Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands.Transcriptional processes regulate abiotic stress responses,yet the molecular regulatory mechanisms in sweet potato remain unclear.In this study,a NAC(NAM,ATAF1/2,and CUC2)transcription factor,IbNAC087,was identified,which is commonly upregulated in salt-and drought-tolerant germplasms.Overexpression of IbNAC087 increased salt and drought tolerance by increasing jasmonic acid(JA)accumulation and activating reactive oxygen species(ROS)scavenging,whereas silencing this gene resulted in opposite phenotypes.JA-rich IbNAC087-OE(overexpression)plants exhibited more stomatal closure than wild-type(WT)and IbNAC087-Ri plants under NaCl,polyethylene glycol,and methyl jasmonate treatments.IbNAC087 functions as a nuclear transcriptional activator and directly activates the expression of the key JA biosynthesisrelated genes lipoxygenase(IbLOX)and allene oxide synthase(IbAOS).Moreover,IbNAC087 physically interacted with a RING-type E3 ubiquitin ligase NAC087-INTERACTING E3 LIGASE(IbNIEL),negatively regulating salt and drought tolerance in sweet potato.IbNIEL ubiquitinated IbNAC087 to promote 26S proteasome degradation,which weakened its activation on IbLOX and IbAOS.The findings provide insights into the mechanism underlying the IbNIEL-IbNAC087 module regulation of JA-dependent salt and drought response in sweet potato and provide candidate genes for improving abiotic stress tolerance in crops.
基金supported by National Natural Science Foundation of China (Nos. 91735302, 31722037, 91435106, 91335203)
文摘Grain size is an important agronomic trait affecting grain yield,but the underlying molecular mechanisms remain to be elucidated.Here,we isolated a dominant mutant,big grainy(bg3-D),which exhibits a remarkable increase of grain size caused by activation of the PURINE PERMEASE gene,OsPUP4.BC3/OSPUP4 is predominantly expressed in vascular tissues and is specifically suppressed by exogenous cytokinin application.Hormone profiling revealed that the distribution of different cytokinin forms,in roots and shoots of the bg3-D mutant,is altered.Quantitative reverse transcription-PCR(qRT-PCR)analysis indicated that expression of rice cytokinin type-A RESPONSE REGULATOR(OsRR)genes is enhanced in the roots of the bgj-D mutant.These results suggest that OSPUP4 might contribute to the long-distance transport of cytokinin,by reinforcing cytokinin loading into vascular bundle cells.Furthermore,plants overexpressing OsPUP7,the closest homolog of OsPUP4,also exhibited a similar phenotype to the bg3-D mutant.Interestingly,subcellular localization demonstrated that OSPUP4 was localized on the plasma membrane,whereas OSPUP7 was localized to the endoplasmic reticulum.Based on these findings,we propose that OSPUP4 and OSPUP7 function in a linear pathway to direct cytokinin cell-to-cell transport,affecting both its long-distance movement and local allocation.
基金supported by the National Key Research and Development Program of China (2016YFD0101601)
文摘The ability of a plant to produce grain, fruit, or forage depends ultimately on photosynthesis. There have been few attempts, however, to study microRNAs, which are a class of endogenous small RNAs post-transcription- ally programming gene expression, in relation to photosynthetic traits. We focused on miR408, one of the most conserved plant miRNAs, and overexpressed it in parallel in Arabidopsis, tobacco, and rice. The transgenic plants all exhibited increased copper content in the chloroplast, elevated abundance of plastocyanin, and an induction of photosynthetic genes. By means of gas exchange and optical spectroscopy analyses, we showed that higher expression of miR408 leads to enhanced photosynthesis through improving efficiency of irradiation utilization and the capacity for carbon dioxide fixation. Consequently, miR408 hyper-accumulat- ing plants exhibited higher rate of vegetative growth. An enlargement of seed size was also observed in all three species overproducing miR408. Moreover, we conducted a 2-year-two-location field trial and observed miR408 overexpression in rice significantly increased yield, which was primarily attributed to an elevation in grain weight. Taken together, these results demonstrate that miR408 is a positive regulator of photosynthesis and that its genetic engineering is a promising route for enhancing photosynthetic performance and yield in diverse plants.
基金supported by the National Key Basic Research Program (973 program) (No. 2006CB100205)the National Science Fund for Distinguished Young Scholars (No. 30825030)+2 种基金the National Natural Science Foundation of China (No. 30770466, 90717110, 30970260 and 30971752)the Earmarked Fund for Modern Agro-industry Technology Research System (No. nycytx-01)the National High Technology Research and Development Program of China (863 Program) (No. 2007AA10Z100)
文摘In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and 3＇ splicing junctions that are distinct from conventional （U2/U12-type） splicing boundaries.By using the known SDR-containing sequences as probes,24 plant candidate genes involved in diverse functional pathways from both monocots and dicots that potentially possess SDR-mediated posttranscriptional processing were predicted in the GenBank database.The SDRs-mediated posttranscriptional processing events including cis-and trans-actions were experimentally detected in majority of the predicted candidates.Extensive sequence analysis demonstrates several types of SDR-associated splicing peculiarities including partial exon deletion,exon fragment repetition,exon fragment scrambling and trans-splicing that result in either loss of partial exon or unusual exonic sequence rearrangements within or between RNA molecules.In addition,we show that the paired presence of SDR is necessary but not sufficient in SDR-mediated splicing in transient expression and stable transformation systems.We also show prokaryote is incapable of SDR-mediated premRNA splicing.
文摘Gibberellins （GAs） are essential phytohormones regulating many aspects of plant growth and development. Manipulation of GA status either by genetic alteration or by exogenous application of GA or GA biosynthesis inhibitors are common strategies used to optimize plant growth and crop yields. Rice （Oryza sativa） is a major source of calories and mineral nutrients, feeding more than half of the human population. With the challenges of feeding an increasing population and decreasing availability of arable land, improving productivity and yields of rice crop has always been an ultimate goal for breeders.
