河南农业大学王桂凤课题组的一项最新研究揭示了Miniature5基因的自然变异决定了玉米线粒体nad1剪接和种子发育。相关论文发表在2026年3月31日出版的《遗传学报》杂志上。

该课题组研究人员报道了玉米Miniature5 （Mn5）的定位克隆，该基因编码线粒体靶向的P类五肽重复（PPR）蛋白。进一步分析表明，Mn5的错义突变Mn5Val109存在于玉米群体中，并与种子大小减小有关。Mn5Val109变体在Mn5-ref突变体中表现出功能受损，无法反接线粒体nad1内含子1，严重降低呼吸复合体I的丰度和活性，并伴有线粒体嵴紊乱。Mn5直接结合到pre-nad1.1转录物的结构域IV。值得注意的是，这个结合位点位于之前假设的3'端下游，它们被线粒体稳定性/加工PPR因子1 （MSP1）结合，它们重新定义了nad1.1 pre-RNA的3'端。

此外，Mn5与成熟酶ZmnMAT1和ZmnMAT3以及广泛参与细胞器II组内含子剪接的PPR蛋白PPR-SMR1和SPR2发生物理相互作用。总之，他们的结果表明，Mn5招募成熟酶和PPR蛋白形成剪接体复合物，负责nad1内含子1的反式剪接。重要的是，Mn5的自然变异赋予了种子大小控制的差异，为培育高产玉米品种提供了潜力。

据介绍，种子大小是决定谷物产量的关键因素，但在玉米育种中很少应用缺陷粒基因的自然变异。

附：英文原文

Title: Natural variation in Miniature5 determines mitochondrial nad1 splicing and seed development in maize

Author: anonymous

Issue&Volume: 2026/03/31

Abstract: Seed size is a key determinant of cereal grain yield, but natural variations in defective-kernel genes have rarely been applied in maize breeding. Here, we report the positional cloning of maize Miniature5 (Mn5), which encodes a mitochondrial-targeted P-class pentatricopeptide repeat (PPR) protein. Further analysis shows that a missense mutation of mn5, Mn5Val109, presents in maize populations and correlates with reduced seed size. The Mn5Val109 variant exhibits compromised function in the mn5-ref mutant, failing to trans-splice mitochondrial nad1 intron1, drastically reducing the abundance and activity of respiratory complex I, accompanied by disorganized mitochondrial cristae. Mn5 directly binds to domain IV of the pre-nad1.1 transcript. Notably, this binding site is located downstream of the previously presumed 3′-terminus bound by MITOCHONDRIA STABILITY/PROCESSING PPR FACTOR1 (MSP1), thus redefining the 3′-end of the nad1.1 pre-RNA. Furthermore, Mn5 physically interacts with the maturases ZmnMAT1 and ZmnMAT3, as well as the PPR proteins PPR-SMR1 and SPR2, which are broadly involved in organellar group II intron splicing. Together, our results suggest that Mn5 recruits maturases and PPR proteins to form spliceosomal complexes responsible for the trans-splicing of nad1 intron1. Importantly, natural variations in Mn5 confer differences in seed size control, offering potential for breeding high-yield maize varieties.

DOI: 10.1016/j.jgg.2026.03.021

Source: https://www.sciencedirect.com/science/article/abs/pii/S1673852726001098