In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unc...In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unclear.In this study,three F2 populations are generated from three Yongyou hybrids to determine the genetic basis of the extremely high yield of intersubspecific hybrids.Genome constitution analysis reveals that the female and male parental lines belong to the Geng and Xian subspecies,respectively,although introgression of 20%of the Xian ancestry and 14%of the Geng ancestry are observed.Twenty-five percent of the hybrid genomes carries homozygous Xian or Geng fragments,which harbors hybrid sterility genes such as Sd,Sc,f5,and q S12 and favorable alleles of key yield-related genes,including NAL1,Ghd7,and Ghd8.None of the parents carries the S5+killer of the S5 killer-protector system.Compatible allele combinations of hybrid sterility genes ensure the fertility of these intersubspecific hybrids and overcome the bottleneck in applying intersubspecific hybrids.Additive effects of favorable alleles of yield-related genes fixed in both parents enhances midparent values.Many QTLs for yield and its key component spikelets per panicle shows dominance and the net positive dominant effects lead to heterosis.These factors result in an extremely high yield of the hybrids.These findings will aid in the development of new intersubspecific rice hybrids with diverse genetic backgrounds.展开更多
CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plan...CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plant height,and heading date2(Ghd2)exhibits a negative response to drought stress by directly upregulating Rubisco activase and exerting a negative effect on heading date.However,the target gene of Ghd2 regulating heading date is still unknown.In this study,CO3 is identified by analyzing Ghd2 ChIP-seq data.Ghd2 activates CO3 expression by binding to the CO3 promoter through its CCT domain.EMSA experiments show that the motif CCACTA in the CO3 promoter was recognized by Ghd2.A comparison of the heading dates among plants with CO3 knocked out or overexpressed and double-mutants with Ghd2 overexpressed and CO3 knocked out shows that CO3 negatively and constantly regulates flowering by repressing the transcription of Ehd1,Hd3a,and RFT1.In addition,the target genes of CO3 are explored via a comprehensive analysis of DAP-seq and RNA-seq data.Taken together,these results suggest that Ghd2 directly binds to the downstream gene CO3,and the Ghd2eCO3 module constantly delays heading date via the Ehd1-mediated pathway.展开更多
Bulked-segregant analysis is a time-and cost-saving strategy for identifying major quantitative trait loci(QTL) in a mapping population. Bulked-segregant analysis combined with whole-genome sequencing(BSA-seq) was per...Bulked-segregant analysis is a time-and cost-saving strategy for identifying major quantitative trait loci(QTL) in a mapping population. Bulked-segregant analysis combined with whole-genome sequencing(BSA-seq) was performed to rapidly identify QTL for heading date, plant height, and panicle length in a large F_(2) population derived from two landraces: Chuan 7(C7) and Haoboka(HBK). Twenty plants with extremely low or high phenotypic values for the target traits were selected from an F_(2) population of 940 plants to construct low-and high-value bulks. Three pairs of bulks for the three traits were constructed, resulting in six DNA pools. BSA-seq revealed nine QTL: four for heading date, three for plant height, and two for panicle length. These QTL were validated in a random F_(2) population or BC_(4)F_(2) populations. The major novel plant height QTL, qPH8, acting additively with an effect equivalent to that of semi-dwarf 1(sd1), is potentially valuable for hybrid rice breeding. qPH8 controls mainly the elongation of basal internodes. The C7 allele of qPH8 reduces plant height and increases lodging resistance without yield penalty, suggesting a potential role for qPH8 in improving rice plant architecture.展开更多
基金partially supported by funds from the National Natural Science Foundation of China (32061143042, 31821005, 91935302)The National Key Research and Development Program of China(2016YFD0100802)
文摘In rice,the Yongyou series of Xian-Geng intersubspecific hybrids have excellent production performance,as shown by their extremely high yield.However,the mechanisms underlying the success of these rice hybrids are unclear.In this study,three F2 populations are generated from three Yongyou hybrids to determine the genetic basis of the extremely high yield of intersubspecific hybrids.Genome constitution analysis reveals that the female and male parental lines belong to the Geng and Xian subspecies,respectively,although introgression of 20%of the Xian ancestry and 14%of the Geng ancestry are observed.Twenty-five percent of the hybrid genomes carries homozygous Xian or Geng fragments,which harbors hybrid sterility genes such as Sd,Sc,f5,and q S12 and favorable alleles of key yield-related genes,including NAL1,Ghd7,and Ghd8.None of the parents carries the S5+killer of the S5 killer-protector system.Compatible allele combinations of hybrid sterility genes ensure the fertility of these intersubspecific hybrids and overcome the bottleneck in applying intersubspecific hybrids.Additive effects of favorable alleles of yield-related genes fixed in both parents enhances midparent values.Many QTLs for yield and its key component spikelets per panicle shows dominance and the net positive dominant effects lead to heterosis.These factors result in an extremely high yield of the hybrids.These findings will aid in the development of new intersubspecific rice hybrids with diverse genetic backgrounds.
基金supported by the Natural Science Foundation of China(U20A2031)the Earmarked Fund for China Agricultural Research System(CARS-01).
文摘CONSTANS,CO-like,and TOC1(CCT)family genes play important roles in regulating heading date,which exerts a large impact on the regional and seasonal adaptation of rice.Previous studies have shown that Grain number,plant height,and heading date2(Ghd2)exhibits a negative response to drought stress by directly upregulating Rubisco activase and exerting a negative effect on heading date.However,the target gene of Ghd2 regulating heading date is still unknown.In this study,CO3 is identified by analyzing Ghd2 ChIP-seq data.Ghd2 activates CO3 expression by binding to the CO3 promoter through its CCT domain.EMSA experiments show that the motif CCACTA in the CO3 promoter was recognized by Ghd2.A comparison of the heading dates among plants with CO3 knocked out or overexpressed and double-mutants with Ghd2 overexpressed and CO3 knocked out shows that CO3 negatively and constantly regulates flowering by repressing the transcription of Ehd1,Hd3a,and RFT1.In addition,the target genes of CO3 are explored via a comprehensive analysis of DAP-seq and RNA-seq data.Taken together,these results suggest that Ghd2 directly binds to the downstream gene CO3,and the Ghd2eCO3 module constantly delays heading date via the Ehd1-mediated pathway.
基金partially supported by the National Natural Science Foundation of China(31701391)the National Key Laboratory of Crop Genetic Improvement Self-Research Program(ZW18B0101)。
文摘Bulked-segregant analysis is a time-and cost-saving strategy for identifying major quantitative trait loci(QTL) in a mapping population. Bulked-segregant analysis combined with whole-genome sequencing(BSA-seq) was performed to rapidly identify QTL for heading date, plant height, and panicle length in a large F_(2) population derived from two landraces: Chuan 7(C7) and Haoboka(HBK). Twenty plants with extremely low or high phenotypic values for the target traits were selected from an F_(2) population of 940 plants to construct low-and high-value bulks. Three pairs of bulks for the three traits were constructed, resulting in six DNA pools. BSA-seq revealed nine QTL: four for heading date, three for plant height, and two for panicle length. These QTL were validated in a random F_(2) population or BC_(4)F_(2) populations. The major novel plant height QTL, qPH8, acting additively with an effect equivalent to that of semi-dwarf 1(sd1), is potentially valuable for hybrid rice breeding. qPH8 controls mainly the elongation of basal internodes. The C7 allele of qPH8 reduces plant height and increases lodging resistance without yield penalty, suggesting a potential role for qPH8 in improving rice plant architecture.
