Characterization, fine mapping and candidate gene analysis of novel, dominant, nuclear male-sterile gene Ms53 in maize

To better understand the molecular mechanism of stamen formation in maize, we used chemical agent ethyl methanesulfonate (EMS) to treat B73 pollens and obtained a Ms53 mutant with no pollen shedding from maize anthers. Ms53 is a completely male-sterile mutant controlled by a single dominant gene; thus, it cannot propagate itself. Microscopic analysis suggested that mutant anthers are smaller in size and lack trichomes on the epidermis surface. Histological analyses revealed that mutant anther abortion occurs at the microspore development stage. Using 1864 individuals from a backcross population derived from Ms53× Mo17, we delimited Ms53 to an interval of approximately 350 kb containing seven annotated genes and flanked by simple repeat sequence (SSR) molecular markers AC196708-4 and AC233922-1. Sequencing analysis of candidate genes from Ms53 and B73 revealed that the 288th amino acid of a SBP-box transcription factor is substituted from glycine to serine and probably leads to the mutant phenotype. These studies will pave the way for elucidating the molecular mechanisms underlying anther development.