Characterization on a Novel Rolled Leaves and Short Petioles Soybean Mutant Based on Seq-BSA and RNA-seq Analysis

A soybean (Glycine max (Linn.) Merr.) mutant displaying rolled leaves and short petioles was identified as being caused by multiple sites, named rlsp1. Compared to wild-type (WT), the phloem structure of petioles in rlsp1 was not obvious, while the thickness of leaves was significantly greater but the arrangement of leaves cells was relatively looser. Sequencing-based bulked segregant analysis (Seq-BSA) identified 10 candidate regions on chromosomes 3, 6, 8, 13, and 17 with total 6.47 Mb, containing 790 genes. 7946 and 5402 differentially expressed genes (DEGs) were also identified in leaves and petioles, respectively, by RNA-sequencing (RNA-seq). Glyma.03G128600 as orthologs of Arabidopsis BOP (BLADE ON PETIOLES) gene may be the key candidate gene causing the variation of rlsp1. The abnormal development of petiole phloem structure, inhibition of auxin signal transduction pathway, promotion of microtubule-related pathways, and repressed of carbohydrate processes were also closely associated with the formation of rlsp1. These results were further validated by the changes of phytohormones, sucrose, Ca2+, and chlorophyll. The candidate genes found in this study enrich the understanding of the molecular basis for the formation of rolled leaves and short petioles in soybean.