Combining Fine Mapping, Whole-Genome Re-Sequencing, and RNA-Seq Unravels Candidate Genes for a Soybean Mutant with Short Petioles and Weakened Pulvini.

A short petiole is an important agronomic trait for the development of plant ideotypes with high yields. However, the genetic basis underlying this trait remains unclear. Here, we identified and characterized a novel soybean mutant with short petioles and weakened pulvini, designated as (). Compared with the wild type (WT), the mutant displayed shortened petioles, owing to the longitudinally decreased cell length, and exhibited a smaller pulvinus structure due to a reduction in motor cell proliferation and expansion. Genetic analysis showed that the phenotype of the mutant was controlled by two recessive nuclear genes, named as and . Using a map-based cloning strategy, the locus was mapped in a 183 kb genomic region on chromosome 14 between markers S1413 and S1418, containing 15 annotated genes, whereas the locus was mapped in a 195 kb genomic region on chromosome 11 between markers S1373 and S1385, containing 18 annotated genes. Based on the whole-genome re-sequencing and RNA-seq data, we identified two homologous genes, and , as the most promising candidate genes for the locus. In addition, the RNA-seq analysis revealed that the expression levels of genes involved in the cytokinin and auxin signaling transduction networks were altered in the mutant compared with the WT. Our findings provide new gene resources for insights into the genetic mechanisms of petiole development and pulvinus establishment, as well as soybean ideotype breeding.