In rice grains,the Waxy (Wx) gene is responsible for the synthesis of amylose,the most important determinant for eating and cooking quality.The effects of several Wx alleles on amylose content and the taste of cooked ...In rice grains,the Waxy (Wx) gene is responsible for the synthesis of amylose,the most important determinant for eating and cooking quality.The effects of several Wx alleles on amylose content and the taste of cooked rice have been elucidated.However,the relationship between artificial selection and the evolution of various Wx alleles as well as their distribution remain unclear.Here we report the identification of an ancestral allele,Wx^lv,which dramatically affects the mouthfeel of rice grains by modulating the size of amylose molecules.We demonstrated that WF originated directly from wild rice,and the three major Wx alleles in cultivated rice (Wx^b,Wx^a,and Wx^in) differentiated after the substitution of one base pair at the functional sites.These data indicate that the Wx^lv allele played an important role in artificial selection and domestication.The findings also shed light on the evolution of various Wx alleles,which have greatly contributed to improving the eating and cooking quality of rice.展开更多
Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa 9 O. latifolia F1 hybrids by treatment with colc...Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa 9 O. latifolia F1 hybrids by treatment with colchicine, an agent for chromosome doubling. Subsequently, amphiploids were investigated using the methods of morphology, genomic in situ hybridization, and molecular markers. Amphiploids were characterized by a shorter plant height, larger diameter of stem, longer and wider leaves, darker leaf color, decreased spikelets per panicle and panicle length, and larger spikelets and anthers than the original F1 hybrid. Based on the mitotic metaphase chromosome number of the investigated root tips, the somatic chromosome number of the amphiploid is 2n = 72.Additionally, the amphiploid is an allohexaploid, and its genomic constitution is AACCDD by genomic in situ hybridization analysis. Finally, the amphiploids were identified to be true using 37 polymorphic markers at the DNA level.展开更多
Seed development in angiosperms requires a 2:1 maternal-to-paternal genome ratio (2m:lp) in the endo- sperm. When the ratio is disrupted, the seed development is impaired. Rice interploidy crosses result in endosp...Seed development in angiosperms requires a 2:1 maternal-to-paternal genome ratio (2m:lp) in the endo- sperm. When the ratio is disrupted, the seed development is impaired. Rice interploidy crosses result in endosperm failures, but the underlying molecular mechanisms remain unclear. Here, we report that the defective endosperm in rice interploidy crosses was associated with nonadditive expression of small RNAs and protein-coding genes. Interestingly, 24-nt small interfering RNAs were enriched in the 5' and 3' flanking sequences of nonadditively expressed genes in the interploidy crosses and were negatively associated with the expression of imprinted genes. Furthermore, some PRC2 family genes and DNA methylaUon-related genes including OsMETlb and OsCMT3a were upregulated in the 2x4 cross (polli- nating a diploid "mother" with a tetraploid "father") but repressed in the reciprocal cross. These different epigenetic effects could lead to precocious or delayed cellularization during endosperm development. Notably, many endosperm-preferred genes, including starch metabolic and storage protein genes during grain filling, were found to be associated with DNA methylation or H3K27me3, which are repressed in both 2×4 and 4 ×2 crosses. WUSCHEL homeobox2 (WOX2)-Iike (WOX2L), an endosperm-preferred gene, was expressed specifically in the rice endosperm, in contrast to WOX2 expression in the Arabidopsis embryo. Disruption of WOX2L in transgenic rice by CRISPR/Cas9-mediated gene editing blocked starch and protein accumulation, resulting in seed abortion. In addition to gene repression, disrupting epigenetic process in the interploidy crosses also induced expression of stress-responsive genes. Thus, maintaining the 2m:lp genome ratio in the endosperm is essential for normal grain development in rice and other cereal crops.展开更多
The centromere of eukaryotic chromosomes is the crucial locus responsible for sister chromatid cohesion and for correct segregation of chromosomes to daughter cells during cell division. In the structural genomics era...The centromere of eukaryotic chromosomes is the crucial locus responsible for sister chromatid cohesion and for correct segregation of chromosomes to daughter cells during cell division. In the structural genomics era, centromeres represent the last frontiers of higher eukaryotic genomes because of their densely methylated, highly repetitive and, heterochromatic DNA (Hall et al., 2004). Although these functions are conserved among all eukaryotes, centromeric DNA sequences are evolving rapidly (Jiang et al., 2003).展开更多
基金supported by the National Natural Science Foundation of China (31825019,31872860,31561143008)the Ministry of Science and Technology of China (2016YFD0100501,2016ZX08009003-004)the programs (BE2018357,BRA2017410,and PAPD) from Jiangsu Government.
文摘In rice grains,the Waxy (Wx) gene is responsible for the synthesis of amylose,the most important determinant for eating and cooking quality.The effects of several Wx alleles on amylose content and the taste of cooked rice have been elucidated.However,the relationship between artificial selection and the evolution of various Wx alleles as well as their distribution remain unclear.Here we report the identification of an ancestral allele,Wx^lv,which dramatically affects the mouthfeel of rice grains by modulating the size of amylose molecules.We demonstrated that WF originated directly from wild rice,and the three major Wx alleles in cultivated rice (Wx^b,Wx^a,and Wx^in) differentiated after the substitution of one base pair at the functional sites.These data indicate that the Wx^lv allele played an important role in artificial selection and domestication.The findings also shed light on the evolution of various Wx alleles,which have greatly contributed to improving the eating and cooking quality of rice.
基金supported by the National Natural Science Foundation of China (31571624, 31071382)the National Basic Research Program of China (2010CB125904, 2013CBA01405)+1 种基金the key Natural Science Project in University of Jiangsu Province (15KJA210004)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Oryza sativa and Oryza latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, amphiploids were obtained from the tube seedlings of O. sativa 9 O. latifolia F1 hybrids by treatment with colchicine, an agent for chromosome doubling. Subsequently, amphiploids were investigated using the methods of morphology, genomic in situ hybridization, and molecular markers. Amphiploids were characterized by a shorter plant height, larger diameter of stem, longer and wider leaves, darker leaf color, decreased spikelets per panicle and panicle length, and larger spikelets and anthers than the original F1 hybrid. Based on the mitotic metaphase chromosome number of the investigated root tips, the somatic chromosome number of the amphiploid is 2n = 72.Additionally, the amphiploid is an allohexaploid, and its genomic constitution is AACCDD by genomic in situ hybridization analysis. Finally, the amphiploids were identified to be true using 37 polymorphic markers at the DNA level.
基金Funding for the research was provided by the National Natural Science Foundation of China (no. 31290213), Research and Education innovation Consortium of Jiangsu Province (2013-2015), Fundamental Research Funds for Central Universities (KYRC201204 and KYZ201202-1), and Jiangsu Collaborative innovation Center for Modern Crop Production (2015-2017).
文摘Seed development in angiosperms requires a 2:1 maternal-to-paternal genome ratio (2m:lp) in the endo- sperm. When the ratio is disrupted, the seed development is impaired. Rice interploidy crosses result in endosperm failures, but the underlying molecular mechanisms remain unclear. Here, we report that the defective endosperm in rice interploidy crosses was associated with nonadditive expression of small RNAs and protein-coding genes. Interestingly, 24-nt small interfering RNAs were enriched in the 5' and 3' flanking sequences of nonadditively expressed genes in the interploidy crosses and were negatively associated with the expression of imprinted genes. Furthermore, some PRC2 family genes and DNA methylaUon-related genes including OsMETlb and OsCMT3a were upregulated in the 2x4 cross (polli- nating a diploid "mother" with a tetraploid "father") but repressed in the reciprocal cross. These different epigenetic effects could lead to precocious or delayed cellularization during endosperm development. Notably, many endosperm-preferred genes, including starch metabolic and storage protein genes during grain filling, were found to be associated with DNA methylation or H3K27me3, which are repressed in both 2×4 and 4 ×2 crosses. WUSCHEL homeobox2 (WOX2)-Iike (WOX2L), an endosperm-preferred gene, was expressed specifically in the rice endosperm, in contrast to WOX2 expression in the Arabidopsis embryo. Disruption of WOX2L in transgenic rice by CRISPR/Cas9-mediated gene editing blocked starch and protein accumulation, resulting in seed abortion. In addition to gene repression, disrupting epigenetic process in the interploidy crosses also induced expression of stress-responsive genes. Thus, maintaining the 2m:lp genome ratio in the endosperm is essential for normal grain development in rice and other cereal crops.
基金supported by the grants from the National Natural Science Foundation of China(Nos.31576124,31071382 and 30771210)the National Basic Research Program of China(973 Program,Nos.2010CB125904 and 2013CBA01405)
文摘The centromere of eukaryotic chromosomes is the crucial locus responsible for sister chromatid cohesion and for correct segregation of chromosomes to daughter cells during cell division. In the structural genomics era, centromeres represent the last frontiers of higher eukaryotic genomes because of their densely methylated, highly repetitive and, heterochromatic DNA (Hall et al., 2004). Although these functions are conserved among all eukaryotes, centromeric DNA sequences are evolving rapidly (Jiang et al., 2003).