研究物種間生殖隔離的機制是進化生物學中的重要工作。水稻兩個亞種——亞洲栽培稻和非洲栽培稻間的雜交不育受S1位點的控制。
為了明確水稻亞種間雜交不育的分子機制,日本的科研人員通過人工誘變和大規模篩選發現了種間可育的突變材料。S1位點的突變是非洲栽培稻中一個肽酶編碼基因SSP的缺失導致的,該基因在亞洲栽培稻中沒有同源位點。轉化實驗證實了SSP基因具有誘導亞種間非洲栽培稻配子缺失的作用。
該位點的發現不僅解釋了水稻亞種間生殖隔離的原因,而且利用該位點可以打破水稻亞種間生殖隔離的限制,從而可以應用更多的優良性狀資源。
PNAS, February 14, 2018
Lineage-specific gene acquisition or loss is involved in interspecific hybrid sterility in rice
Author
Yohei Koide, Atsushi Ogino, Takanori Yoshikawa……Yoshimichi Fukuta, Yutaka Okumoto and Akira Kanazawa*
Research Faculty of Agriculture, Hokkaido University, Japan
Abstract
Understanding the genetic basis ofreproductive barriers between species has been a central issue in evolutionary biology. The S1 locus in rice causes hybrid sterility and is a major reproductive barrier between two rice species, Oryza sativa and Oryza glaberrima. The O. glaberrima-derived allele (denoted S1g) on the S1 locus causes preferential abortion of gametes with its allelic alternative (denoted S1s) in S1g/S1s heterozygotes. Here, we used mutagenesis and screening of fertile hybrid plants to isolate a mutant with an allele, S1mut, which does not confer sterility in the S1mut/S1g and S1mut/S1s hybrids. We found that the causal mutation of the S1mut allele was a deletion in the peptidase-coding gene (denoted 「SSP」) in the S1 locusof O. glaberrima. No orthologous genes of SSP were found in the O. sativa genome. Transformation experiments indicated that the introduction of SSP in carriers of the S1s allele did not induce sterility. In S1mut/S1s heterozygotes, the insertion of SSP led to sterility, suggesting that SSP complemented the loss of the functional phenotype of the mutant and that multiple factors are involved in the phenomenon. The polymorphisms caused by the lineage-specific acquisition or loss of the SSP gene were implicated in the generation of hybrid sterility. Our results demonstrated that artificial disruption of a single gene for the reproductive barrier creates a 「neutral」 allele, which facilitates interspecific hybridization for breeding programs.
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