Molecular regulation ofZmMs7required for maize male fertility and development of a dominant male-sterility system in multiple species

Abstract

Understanding the molecular basis of male sterility and developing practical male-sterility systems are essential for heterosis utilization and commercial hybrid seed production in crops. Here, we report molecular regulation by genic male-sterility genemaize male sterility 7(ZmMs7) and its application for developing a dominant male-sterility system in multiple species.ZmMs7is specifically expressed in maize anthers, encodes a plant homeodomain (PHD) finger protein that functions as a transcriptional activator, and plays a key role in tapetal development and pollen exine formation. ZmMs7 can interact with maize nuclear factor Y (NF-Y) subunits to form ZmMs7-NF-YA6-YB2-YC9/12/15 protein complexes that activate target genes by directly binding to CCAAT box in their promoter regions. Premature expression ofZmMs7in maize by an anther-specific promoterp5126results in dominant and complete male sterility but normal vegetative growth and female fertility. Early expression ofZmMs7downstream genes induced by prematurely expressed ZmMs7 leads to abnormal tapetal development and pollen exine formation inp5126-ZmMs7maize lines. Thep5126-ZmMs7transgenic rice andArabidopsisplants display similar dominant male sterility. Meanwhile, themCherrygene coupled withp5126-ZmMs7facilitates the sorting of dominant sterility seeds based on fluorescent selection. In addition, both thems7-6007recessive male-sterility line andp5126-ZmMs7Mdominant male-sterility line are highly stable under different genetic germplasms and thus applicable for hybrid maize breeding. Together, our work provides insight into the mechanisms of anther and pollen development and a promising technology for hybrid seed production in crops.