Genetic mapping and functional analysis of a classical tassel branch number mutant in maize.

Tassel branch number is a key trait that contributes greatly to grain yield in maize (). We obtained a classical mutant from maize genetics cooperation stock center, (), which exhibits severely decreased tassel branch. We conducted a comprehensive study, including phenotypic investigation, genetic mapping, transcriptome analysis, overexpression and CRISPR knock-out, and tsCUT&Tag of gene for the molecular dissection of mutant. Phenotypic investigation showed that it is a pleiotropic dominant mutant, which is mapped to an interval of approximately 139-kb on Chromosome 10 harboring two genes and . Transcriptome analysis showed that the relative expression level of was significantly increased in mutants. Meanwhile, overexpression of and knockout materials of exhibited significantly decreased tassel branch number, a similar phenotype with mutant, suggesting that is the causal gene of and targets gene. Besides, the potential downstream genes of were uncovered and showed that it may target multiple proteins to regulate inflorescence structure. Overall, we characterized and cloned mutant, and proposed a zma-miR156h-ZmSBP13 model functioning in regulating tassel branch development in maize, which is an essential measure to satisfy the increasing demands of cereals.