Postmeiotic irregular anther1 (PIA1) is required for anther cuticle and pollen exine development in maize (Zea mays L.)

Male sterile lines are valuable germplasm resources for hybrid seed production in maize (Zea mays L.). The structures of the anther cuticle and pollen exine are associated with male sterility. We obtained a completely male sterile mutant (postmeiotic irregular anther1, pia1), which has closed glumes and relatively small and wilted anthers (compared with the wild-type control). Cytological analysis revealed the normal meiosis and premature tapetal degradation in pia1. Additionally, formation of the pia1 anther cuticle and Ubisch bodies was abnormal, and the pollen exine was discontinuous. Genetic analysis showed that the pia1 mutant was the result of a single recessive mutation of a nuclear gene. On the basis of fine mapping, PIA1 was mapped between the W07051 and W07124 molecular markers on chromosome 1. This region does not contain known genes associated with male sterility. Furthermore, transcriptome analysis indicated genes implicated in transmembrane transport, amino acid transmembrane transport, amino acid transport, and carboxylic acid transmembrane transport are differentially expressed in pia1 mutant anthers. The study findings suggest PIA1 is a novel regulator of anther cuticle and pollen exine development.