Guangdong Provincial Key Laboratory of Plant Molecular Breeding, College of Agriculture, South China Agricultural University, Guangzhou, Guangdong, 510642, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, Guangdong, 510642, China.
Nat Commun. 2023 Jul 28;14(1):4531. doi: 10.1038/s41467-023-40189-x.
Understanding the evolutionary forces in speciation is a central goal in evolutionary biology. Asian cultivated rice has two subspecies, indica and japonica, but the underlying mechanism of the partial reproductive isolation between them remains obscure. Here we show a presence-absence variation (PAV) at the Se locus functions as an indica-japonica reproductive barrier by causing hybrid sterility (HS) in indica-japonica crosses. The locus comprises two adjacent genes: ORF3 encodes a sporophytic pollen killer, whereas ORF4 protects pollen in a gametophytic manner. In F of indica-japonica crosses, pollen with the japonica haplotype, which lacks the sequence containing the protective ORF4, is aborted due to the pollen-killing effect of ORF3 from indica. Evolutionary analysis suggests ORF3 is a gene associated with the Asian cultivated rice species complex, and the PAV has contributed to the reproductive isolation between the two subspecies of Asian cultivated rice. Our analyses provide perspectives on rice inter-subspecies post-zygotic isolation, and will promote efforts to overcome reproductive barriers in indica-japonica hybrid rice breeding.
理解物种形成中的进化力量是进化生物学的一个核心目标。亚洲栽培稻有两个亚种，籼稻和粳稻，但它们之间部分生殖隔离的潜在机制仍不清楚。在这里，我们发现 Se 基因座的存在-缺失变异 (PAV) 可作为籼粳亚种间的生殖障碍，导致籼粳亚种间杂交的杂种不育 (HS)。该基因座由两个相邻的基因组成：ORF3 编码一个孢子体花粉杀手，而 ORF4 以配子体的方式保护花粉。在籼粳亚种间的 F1 杂交中，由于来自籼稻的 ORF3 的花粉杀伤效应，缺乏包含保护 ORF4 的序列的粳稻单倍型的花粉会被中止。进化分析表明，ORF3 是与亚洲栽培稻种复合体相关的基因，而 PAV 促成了两个亚种之间的生殖隔离。我们的分析为水稻亚种间合子后隔离提供了新视角，并将促进克服籼粳杂交稻育种中生殖障碍的努力。
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