Abstract:

In order to reduce the labor costs and guarantee the seed purity, male sterility gene was applied to sweet corn hybrid seed production. We used male sterility 2020 (ms2020), a spontaneous male sterility mutant derived from sweet corn inbred line K78, as the experimental material to construct F₁ and corresponding F₂ populations of ms2020 and sweet corn inbred line M08. We performed phenotypic identification, genetic analysis, and gene mapping for ms2020 mutant. Phenotypic identification showed that the F₁ population was fertile, and the F₂ population was partially sterile. The sterile plants could be tasseled normally, but the anthers were not exposed, no pollen shed, anthers small, and pale yellow. Employing 1% I₂-KI staining showed that the anthers of sterile plants contained abortive pollen grains that could not stain normally. The results of genetic analysis showed that the ratio of fertile normal plants to sterile plants was 3∶1, indicating that ms2020 male sterile mutant was a recessive mutant controlled by a single gene. The target gene was initially located on the short arm of chromosome 7 by the BSA method. Subsequently, 20 pairs of SSR markers in the initial interval were used to locate the sterile gene, and gene was finely located between markers S1 and W10, with a physical distance of 11.30 kb. Two genes, Zm00001d018802 and Zm00001d018803 were included in this region. Based on the functional analysis of candidate genes, it is speculated that Zm00001d018802 (ZmMs22/ZmMSCA1) encoding gludodoxin, which has been reported as a male sterility gene in maize, may be the key candidate gene for ms2020.The abortion characteristics and genetic regularity of ms2020 male sterility mutant were identified, which provided the material for male sterility hybridization seed production of sweet corn. The key candidate gene of the mutant were located, which laid a foundation for further analysis of its molecular mechanism.

Key words: Maize, Male sterility, Gene mapping, Hybrid seed production