Mapping and Functional Analysis of a Maize Silkless Mutant .

The maize () stigma, which is commonly known as silk, is indispensable for reproduction and thus for grain yield. Here, we isolated a spontaneous mutant , which completely lacks silk; scanning electron microscopy showed that the pistils degenerated during late floret differentiation. Genetic analysis confirmed that this trait was controlled by a recessive nuclear gene and was mapped to a 74.13-kb region on chromosome 2 between the simple sequence repeat markers and . Sequence analysis of candidate genes in this interval identified a single-nucleotide insertion at position 569 downstream of the transcriptional start site in , which encodes a UDP-glycosyltransferase; this insertion produces a frameshift and premature translational termination. RNA-sequencing analysis of young ears identified 258 differentially expressed genes (DEGs) between and the wild type (WT), including 119 up- and 139 down-regulated genes. Interestingly, most DEGs related to jasmonic acid (JA) synthesis were up-regulated in the mutant compared to WT. Consistent with this, the JA and JA-Isoleucine (JA-Ile) contents were significantly higher in ears than in WT. At the same time, RNA-sequencing analysis of tassels showed that could reduce the number of tassel branches in maize by down-regulating the expression of and genes. Our identification of the mutant and the responsible gene will facilitate further studies on female infertility research or maize breeding.