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
The twin challenges of an expanding world population and environmental crises make securing a stable food supply by increasing crop yields and improving stress tolerance a major global imperative.Hybrid varieties,deve...The twin challenges of an expanding world population and environmental crises make securing a stable food supply by increasing crop yields and improving stress tolerance a major global imperative.Hybrid varieties,developed and used in a wide range of crops in recent years,are produced,in many cases,by crossing local inbred varieties.These hybrids are increasingly in demand because of their potential for robust yield and stress tolerance characteristics.Over the past half century,great efforts have been made in both basic and applied science to develop hybrid varieties of rice(Oryza sativa),with the first practical application beginning in China around 1970.Hybrid rice varieties can be expected to increase yields by around 20%compared to conventional inbred lines due to the heterosis effect.展开更多
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T.K.is supported by a grant from the JSPS KAKENHI(grant no.20K05985).
文摘The twin challenges of an expanding world population and environmental crises make securing a stable food supply by increasing crop yields and improving stress tolerance a major global imperative.Hybrid varieties,developed and used in a wide range of crops in recent years,are produced,in many cases,by crossing local inbred varieties.These hybrids are increasingly in demand because of their potential for robust yield and stress tolerance characteristics.Over the past half century,great efforts have been made in both basic and applied science to develop hybrid varieties of rice(Oryza sativa),with the first practical application beginning in China around 1970.Hybrid rice varieties can be expected to increase yields by around 20%compared to conventional inbred lines due to the heterosis effect.
