Anther development and male fertility are essential biological pro- cesses for flowering plants and are important for crop seed produc- tion. Genetic manipulation of male fertility/sterility is critical for crop hybri...Anther development and male fertility are essential biological pro- cesses for flowering plants and are important for crop seed produc- tion. Genetic manipulation of male fertility/sterility is critical for crop hybrid breeding. Rice （Oryza sativa L.） male sterility phenotypes, including genic male sterility, hybrid male sterility, and cytoplasmic male sterility, are generally caused by mutations of fertility-related genes, by incompatible interactions between divergent allelic or non-allelic genes, or by genetic incompatibilities between cytoplas-mic and nuclear genomes. Here, we review the recent advances in the molecular basis of anther development and male fertility-sterility conversion in specific genetic backgrounds, and the interactions with certain environmental factors. The highlighted findings in this review have significant implications in both basic studies and rice genetic improvement.展开更多
Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we chara...Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.展开更多
Hybrid sterility is a major form of postzygotic reproductive isolation and frequently occurs in hybrids between divergent populations, such as the indica and japonica subspecies of Asian cultivated rice (Oryza sativa ...Hybrid sterility is a major form of postzygotic reproductive isolation and frequently occurs in hybrids between divergent populations, such as the indica and japonica subspecies of Asian cultivated rice (Oryza sativa L.). It has been a major barrier for utilization of the strong heterosis expressed in hybrids between indica and japonica. A large number of loci for rice inter-subspecific hybrid sterility have been identified by genetic analysis. Cytological studies revealed that male and female gamete abortions and reduced affinity between the uniting gametes all occurred in indica-japonica hybrids, suggesting the complexity of the causes for inter-subspecific hybrid sterility. Two genes conditioning embryo-sac and pollen sterility respectively in indica-japonica hybrids have been cloned recently, providing opportunities for molecular characterization of the indica-japonica hybrid sterility and wide-compatibility. Future studies should aim at cloning more genes for indica-japonica hybrid sterility, characterizing the underlying molecular mechanism, and utilization of the findings for the development of inter-subspecific hybrids to increase rice productivity.展开更多
Reproductive isolation is defined as processes that prevent individuals of different populations from mating, survival or producing fertile offspring. Reproductive isolation is critical for driving speciation and main...Reproductive isolation is defined as processes that prevent individuals of different populations from mating, survival or producing fertile offspring. Reproductive isolation is critical for driving speciation and maintaining species identity, which has been a fundamental concern in evolutionary biology. In plants,reproductive isolation can be divided into prezygotic and postzygotic reproductive barriers, according to its occurrence at different developmental stages. Postzygotic reproductive isolation caused by reduced fitness in hybrids is frequently observed in plants, which hinders gene flow between divergent populations and has substantial effects on genetic differentiation and speciation, and thus is a major obstacle for utilization of heterosis in hybrid crops. During the past decade, China has made tremendous progress in molecular and evolutionary basis of prezygotic and postzygotic reproductive barriers in plants. Present understandings in reproductive isolation especially with new data in the last several years well support three evolutionary genetic models, which represent a general mechanism underlying genomic differentiation and speciation. The updated understanding will offer new approaches for the development of wide-compatibility or neutral varieties, which facilitate breeding of hybrid rice as well as other hybrid crops.展开更多
Hybrid sterility is the main barrier in util-izing the heterosis of subspecies in rice. A knowledge of the underlying molecular mechanism of the hybrid sterility will be useful for overcoming the barrier. In this rese...Hybrid sterility is the main barrier in util-izing the heterosis of subspecies in rice. A knowledge of the underlying molecular mechanism of the hybrid sterility will be useful for overcoming the barrier. In this research, the F1 pollen sterility locus, S-b, was mapped between SSR markers PSM8 and PSM202. To fine map the locus, one F2 mapping population of 3910 plants was developed using the near-isogenic lines of the locus. Ninety-seven recombinants be-tween two markers were selected. Moreover, a series of markers, including two SSR markers, two InDel markers and four CAPS markers, were developed on the region. Linkage analysis showed that marker W4 was co-segregated with locus S-b, while makers A8 and A14 were located on the two sides of the locus with a distance of 0.026 and 0.038 cM, respectively. The markers were then integrated with the se-quences of the clones of the region. Results showed that all the polymorphic markers were anchored on the three end-to-end jointed clones AC093089, AC079021 and AC134931. According to the physical information of the markers, locus S-b was finally de-limited to a region of 27 kb between A8 and A14. Seven ORFs were identified on the region based on the annotation results of RiceGAAS system. These results laid the foundation for further cloning the gene.展开更多
The Asian cultivated rice(Oryza sativa L.) grown worldwide is divided into two subspecies, indica and japonica. It is well known that the heterosis of inter-subspecies is usually stronger than that of intra-subspecies...The Asian cultivated rice(Oryza sativa L.) grown worldwide is divided into two subspecies, indica and japonica. It is well known that the heterosis of inter-subspecies is usually stronger than that of intra-subspecies. Since the 1970 s, indica hybrid rice, an intra-subspecific hybrid rice, has being widely used in China and even in the world. However, the inter-subspecific hybrid rice between indica and japonica is still unavailable. The major obstacle is the hybrid sterility of the inter-subspecies. In recent decades, the genetic and molecular basis of indica-japonica hybrid sterility was understood more and more clearly. Some breeding approaches for overcoming inter-subspecific hybrid sterility were proposed and used to develop the indicajaponica hybrid rice. The updated understanding will offer new approaches for development of breeding lines for overcoming indica-japonica hybrid sterility, which facilitates developing of inter-subspecific hybrid rice.展开更多
Hybrid sterility presents a major bottleneck in hybrid crop breeding and causes postzygotic reproductive isolation in speciation.Here, we summarize the current understanding of the genetics of rice hybrid sterility an...Hybrid sterility presents a major bottleneck in hybrid crop breeding and causes postzygotic reproductive isolation in speciation.Here, we summarize the current understanding of the genetics of rice hybrid sterility and highlight new advances in deciphering the molecular basis of the major genetic loci for hybrid sterility in rice. We also discuss practical strategies for overcoming reproductive barriers to utilize hybrid vigor in inter-specific and inter-subspecific hybrid rice breeding.展开更多
Oryza sativa and O. alta belong to AA and CCDD genomes in Oryza, respectively. Interspecific repro-ductive isolation limits the transfer of favorable genes from O. alta into O. sativa. The cytological mechanisms of in...Oryza sativa and O. alta belong to AA and CCDD genomes in Oryza, respectively. Interspecific repro-ductive isolation limits the transfer of favorable genes from O. alta into O. sativa. The cytological mechanisms of interspecific incrossability and hybrid sterility between O. sativa and O. alta were studied systematically in this paper. We indentified two cytological causes of interspecific incrossabil-ity. First, we observed embryo sac incompatibility that caused fertilization barriers of variable severity such as non-fertilization, fertilization stagnation and egg cell single-fertilization. Second, we observed hybrid inviability, the major cause for incrossability, apparent from hybrid embryo developmental stagnation and embryo abortion. Hybrid sterility included both embryo sac sterility and pollen sterility. The hybrid embryo sac was completely sterile and exhibited mainly embryo sac degeneration. Hybrid pollen was also sterile and mainly typical abortive. Hybrid sterility was mainly caused by severely ab-normal meioses of megasporocytes and pollen mother cells; it is the most important abnormality, being chromosome sterility. Several methods are suggested to overcome the interspecific reproductive iso-lation between O. sativa and O. alta.展开更多
基金supported by a grant from the National Basic Research Program of China(973 Program,2011CB100203)
文摘Anther development and male fertility are essential biological pro- cesses for flowering plants and are important for crop seed produc- tion. Genetic manipulation of male fertility/sterility is critical for crop hybrid breeding. Rice （Oryza sativa L.） male sterility phenotypes, including genic male sterility, hybrid male sterility, and cytoplasmic male sterility, are generally caused by mutations of fertility-related genes, by incompatible interactions between divergent allelic or non-allelic genes, or by genetic incompatibilities between cytoplas-mic and nuclear genomes. Here, we review the recent advances in the molecular basis of anther development and male fertility-sterility conversion in specific genetic backgrounds, and the interactions with certain environmental factors. The highlighted findings in this review have significant implications in both basic studies and rice genetic improvement.
文摘Molecular mechanisms of hybrid breakdown associated with sterility (F<sub>2</sub> sterility) are poorly understood as compared with those of F<sub>1</sub> hybrid sterility. Previously, we characterized three unlinked epistatic loci, hybrid sterility-a1 (hsa1), hsa2, and hsa3, responsible for the F<sub>2</sub> sterility in a cross between Oryza sativa ssp. indica and japonica. In this study, we identified that the hsa1 locus contains two interacting genes, HSA1a and HSA1b, within a 30-kb region. HSA1a-j (japonica allele) encodes a highly conserved plant-specific domain of unknown function protein (DUF1618), whereasthe indica allele (HSA1a-i<sup>s</sup>) has two deletion mutations that cause disruption of domain structure. The second gene, HSA1b-i<sup>s</sup>, encodes an uncharacterized proteinwith some similarity to a nucleotide-binding protein. Homozygous introgression of indica HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> alleles into japonica showed female gamete abortion at an early mitotic stage. The fact that the recombinant haplotype HSA1a-j-HSA1b-i<sup>s</sup> caused semi-sterility in the heterozygous state with the HSA1a-i<sup>s</sup>-HSA1b-i<sup>s</sup> haplotype suggests that variation in the hsa1 locus is a possible cause of the wide-spectrum sterility barriers seen in F<sub>1</sub> hybrids and successive generations in rice. We propose a simple genetic model to explain how a single causal mechanism can drive both F<sub>1</sub> and F<sub>2</sub> hybrid sterility.
基金Supported by grants partially from the National Special Key Project of China on Functional Genomics of Major Plants and Animals (Grant No. 2006AA10A103)National Natural Science Foundation of China (Grant No. 30621065)
文摘Hybrid sterility is a major form of postzygotic reproductive isolation and frequently occurs in hybrids between divergent populations, such as the indica and japonica subspecies of Asian cultivated rice (Oryza sativa L.). It has been a major barrier for utilization of the strong heterosis expressed in hybrids between indica and japonica. A large number of loci for rice inter-subspecific hybrid sterility have been identified by genetic analysis. Cytological studies revealed that male and female gamete abortions and reduced affinity between the uniting gametes all occurred in indica-japonica hybrids, suggesting the complexity of the causes for inter-subspecific hybrid sterility. Two genes conditioning embryo-sac and pollen sterility respectively in indica-japonica hybrids have been cloned recently, providing opportunities for molecular characterization of the indica-japonica hybrid sterility and wide-compatibility. Future studies should aim at cloning more genes for indica-japonica hybrid sterility, characterizing the underlying molecular mechanism, and utilization of the findings for the development of inter-subspecific hybrids to increase rice productivity.
基金supported by grants from the National Key Research and Development Program of China (2016YFD0100801)the National Natural Science Foundation of China (No.31771873)the National Program for Support of Top-notch Young Professionals
文摘Reproductive isolation is defined as processes that prevent individuals of different populations from mating, survival or producing fertile offspring. Reproductive isolation is critical for driving speciation and maintaining species identity, which has been a fundamental concern in evolutionary biology. In plants,reproductive isolation can be divided into prezygotic and postzygotic reproductive barriers, according to its occurrence at different developmental stages. Postzygotic reproductive isolation caused by reduced fitness in hybrids is frequently observed in plants, which hinders gene flow between divergent populations and has substantial effects on genetic differentiation and speciation, and thus is a major obstacle for utilization of heterosis in hybrid crops. During the past decade, China has made tremendous progress in molecular and evolutionary basis of prezygotic and postzygotic reproductive barriers in plants. Present understandings in reproductive isolation especially with new data in the last several years well support three evolutionary genetic models, which represent a general mechanism underlying genomic differentiation and speciation. The updated understanding will offer new approaches for the development of wide-compatibility or neutral varieties, which facilitate breeding of hybrid rice as well as other hybrid crops.
文摘Hybrid sterility is the main barrier in util-izing the heterosis of subspecies in rice. A knowledge of the underlying molecular mechanism of the hybrid sterility will be useful for overcoming the barrier. In this research, the F1 pollen sterility locus, S-b, was mapped between SSR markers PSM8 and PSM202. To fine map the locus, one F2 mapping population of 3910 plants was developed using the near-isogenic lines of the locus. Ninety-seven recombinants be-tween two markers were selected. Moreover, a series of markers, including two SSR markers, two InDel markers and four CAPS markers, were developed on the region. Linkage analysis showed that marker W4 was co-segregated with locus S-b, while makers A8 and A14 were located on the two sides of the locus with a distance of 0.026 and 0.038 cM, respectively. The markers were then integrated with the se-quences of the clones of the region. Results showed that all the polymorphic markers were anchored on the three end-to-end jointed clones AC093089, AC079021 and AC134931. According to the physical information of the markers, locus S-b was finally de-limited to a region of 27 kb between A8 and A14. Seven ORFs were identified on the region based on the annotation results of RiceGAAS system. These results laid the foundation for further cloning the gene.
基金supported by the National Natural Science Foundation of China (91435207 and 91735304)the Project of Science and Technology of Guangzhou, China (201607020040)
文摘The Asian cultivated rice(Oryza sativa L.) grown worldwide is divided into two subspecies, indica and japonica. It is well known that the heterosis of inter-subspecies is usually stronger than that of intra-subspecies. Since the 1970 s, indica hybrid rice, an intra-subspecific hybrid rice, has being widely used in China and even in the world. However, the inter-subspecific hybrid rice between indica and japonica is still unavailable. The major obstacle is the hybrid sterility of the inter-subspecies. In recent decades, the genetic and molecular basis of indica-japonica hybrid sterility was understood more and more clearly. Some breeding approaches for overcoming inter-subspecific hybrid sterility were proposed and used to develop the indicajaponica hybrid rice. The updated understanding will offer new approaches for development of breeding lines for overcoming indica-japonica hybrid sterility, which facilitates developing of inter-subspecific hybrid rice.
基金supported by grants from the Key Research Program of Guangzhou Science Technology and Innovation Commission (201707020016)the National Natural Science Foundation of China (31471564, 31701499)the China Postdoctoral Science Foundation (2018M630955)
文摘Hybrid sterility presents a major bottleneck in hybrid crop breeding and causes postzygotic reproductive isolation in speciation.Here, we summarize the current understanding of the genetics of rice hybrid sterility and highlight new advances in deciphering the molecular basis of the major genetic loci for hybrid sterility in rice. We also discuss practical strategies for overcoming reproductive barriers to utilize hybrid vigor in inter-specific and inter-subspecific hybrid rice breeding.
基金The financial support for the present study from National Natural Science Foundation of China(30260058)Scientific and Technological Development Foundation of Guangxi Academy of Agricultural Sciences is thankfully acknowledged..
基金Supported by the Guangdong provincial key project of Natural Science Foun-dation (Grant No. 021037)Gaozhou wild rice initiative project from Agri-culture Department of Guangdong Province (Grant No. 360 (2003))
文摘Oryza sativa and O. alta belong to AA and CCDD genomes in Oryza, respectively. Interspecific repro-ductive isolation limits the transfer of favorable genes from O. alta into O. sativa. The cytological mechanisms of interspecific incrossability and hybrid sterility between O. sativa and O. alta were studied systematically in this paper. We indentified two cytological causes of interspecific incrossabil-ity. First, we observed embryo sac incompatibility that caused fertilization barriers of variable severity such as non-fertilization, fertilization stagnation and egg cell single-fertilization. Second, we observed hybrid inviability, the major cause for incrossability, apparent from hybrid embryo developmental stagnation and embryo abortion. Hybrid sterility included both embryo sac sterility and pollen sterility. The hybrid embryo sac was completely sterile and exhibited mainly embryo sac degeneration. Hybrid pollen was also sterile and mainly typical abortive. Hybrid sterility was mainly caused by severely ab-normal meioses of megasporocytes and pollen mother cells; it is the most important abnormality, being chromosome sterility. Several methods are suggested to overcome the interspecific reproductive iso-lation between O. sativa and O. alta.
