Deng Ruilian, You Hanli, Ge Qi, Wu Jinwen, Cheng Zhukuan, Zhu Lianjun, Yu Hang, Chen Lin, Shahid Muhammad Qasim, Lu Zijun, Liu Xiangdong
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, 510642, China.
Guangdong Provincial Key Laboratory of Plant Molecular Breeding, Guangdong Base Bank for Lingnan Rice Germplasm Resources, College of Agriculture, South China Agricultural University, Guangzhou, 510642, China.
Rice (N Y). 2025 Aug 18;18(1):77. doi: 10.1186/s12284-025-00835-y.
Interspecific and intersubspecific hybrid rice have demonstrated substantial heterosis and increased yield potential, yet they are frequently restricted by complex hybrid sterility (HS). Gene regulation has primarily been used to explain the genetic mechanism of HS; however, it is still unclear how cryptic chromosomal structural hybridity results in heterozygote semi-sterility at the molecular level. This study identified a T-DNA-mediated heterozygous mutant mfss (male and female semi-sterility) in rice, of which the self-pollinated progeny would produce heterozygous semi-sterile mutant plants and homozygous fertile mutant plants, mm, with homozygous in inserted T-DNA. The hybrids derived from mm plants crossing with other rice varieties exhibited conservative semi-sterility. Genomic analyses and fluorescence in situ hybridization (FISH) observation revealed that the end of chromosome 6 (170 genes) translocated with the end of chromosome 2 (566 genes) in mm plants. Among these 736 translocated genes, 102 reproduction-concerned genes, including a new gene, MCM5, were detected, which may result in half of gametes lacking many reproduction-concerned genes to display sterility and caused semi-sterility of mfss-heterozygotes. Hybrids derived from an autotetraploid rice line created from mm plants by genome duplication crossed with a neo-tetraploid rice displayed high fertility, implying that the mfss-heterozygote semi-sterility might be overcome by producing polyploid hybrid rice. These findings elucidate the genetic process of reciprocal translocation causing the heterozygote semi-sterility in rice and offer valuable insights for the production of fertile polyploid hybrid rice.
种间和亚种间杂交水稻已表现出显著的杂种优势和更高的产量潜力，但它们常常受到复杂的杂种不育（HS）的限制。基因调控主要用于解释HS的遗传机制；然而，目前仍不清楚隐秘的染色体结构杂种性如何在分子水平上导致杂合子半不育。本研究在水稻中鉴定出一个T-DNA介导的杂合突变体mfss（雌雄半不育），其自花授粉后代会产生杂合半不育突变体植株和纯合可育突变体植株mm，mm在插入的T-DNA处为纯合状态。mm植株与其他水稻品种杂交产生的杂种表现出保守的半不育性。基因组分析和荧光原位杂交（FISH）观察表明，mm植株中6号染色体末端（170个基因）与2号染色体末端（566个基因）发生了易位。在这736个易位基因中，检测到102个与生殖相关的基因，包括一个新基因MCM5，这可能导致一半的配子缺乏许多与生殖相关的基因而表现出不育，从而导致mfss杂合子的半不育。由mm植株通过基因组加倍产生的同源四倍体水稻品系与新四倍体水稻杂交产生的杂种表现出高育性，这意味着通过培育多倍体杂交水稻可能克服mfss杂合子的半不育性。这些发现阐明了相互易位导致水稻杂合子半不育的遗传过程，并为培育可育的多倍体杂交水稻提供了有价值的见解。
