Characterization and genetic analysis of a new allelic mutant of Miniature1 gene in maize

Grain development is a key determinant for maize grain yield and quality, but the regulatory mechanisms have not been fully revealed. A maize mutant deficient in kernel development was found and selected in our field. The mutant exhibited an incomplete grain filling, reduced embryo and endosperm size, and shriveled mature grains and empty pericarp. Genetic analysis suggested that the mutant phenotype was controlled by a single recessive nuclear gene. The candidate gene was preliminarily mapped to a 1.1 Mb interval on chromosome 2, and further a hAT transposon was inserted into the first exon of Miniature1 (Mn1) gene, which resulting in a frame-shift mutation and down-regulated expression of Mn1. The transposon insertion was fully linked to the defective kernel phenotype of the mutant, which was nominated as mn1-m2. Allelism test of mn1-m2 and mn1-89 suggested that mn1-m2 was a noval allelic mutant of Mn1 gene. In conclusion, we identified a new allelic mutant of Mn1 gene with different mutation site and type, which improved maize germplasm resources and provided new genetic materials for the analysis of the mechanism of Mn1 regulation on kernel development.