Maize CRM-domain family protein CFM1 regulates kernel development via plastid group II intron splicing

Embryogenesis in plants is a complex process, and proteins encoded by genes that affect embryo development in maize are typically localized in plastids. In this study, we isolated a maize embryo-specific defective mutant (emb) in which the mutant embryos were arrested at the transition stage and the endosperm size was reduced compared to the wild type (WT). The grain-filling rate of zmcfm1 was significantly lower than that of the WT, resulting in a markedly reduced weight of mature grains. The mutant gene ZmCFM1 was identified by bulked segregant analysis sequencing and map-based cloning. ZmCFM1 encodes a plastid-localized CRM family protein involved in the splicing of group II introns in plastids. The splicing efficiency of the trnA, trnI, trnK, trnV, and rpl2 introns in the plastids of zmcfm1 was significantly reduced. The impairment of intron splicing disrupts ribosome assembly and plastid protein translation, ultimately causing embryo arrest and lethality.

The online version contains supplementary material available at 10.1007/s11032-026-01643-y.