A DIRIGENT Gene GmDIR26 Regulates Pod Dehiscence in Soybean

Pod dehiscence brings much loss for modern agricultural production, and multiple pod dehiscence components have been identified in many plant species. However, the pod dehiscence regulation factors in soybean are limited. In this study, we investigate the function of GmDIR26, a close homologues gene of pod dehiscence genes GmPdh1, PvPdh1, and CaPdh1, in the regulation of pod dehiscence in soybean. The secondary and tertiary structure analysis reveals that GmDIR26 protein has a similar structure with GmPdh1, PvPdh1, and CaPdh1 proteins. Synteny analysis of soybean and chickpea genomes shows that the genomic region surrounding GmDIR26 and CaPdh1 might be evolved from the same ancestor, and these two genes might have similar function. GmDIR26 shows an increased expression pattern during pod development and reaches a peak at beginning seed stage. Meanwhile, GmDIR26 exhibits high expression levels in dorsal suture and pod wall, but low expression pattern in ventral suture. In addition, GmDIR26 shows higher expression levels in pod dehiscence genotype than that in pod indehiscence accessions. Overexpression of GmDIR26 in soybean increases pod dehiscence in transgenic plants, of which the lignin layer in inner sclerenchyma pods is thicker and looser. The expression levels of several pod dehiscence genes are altered. Our study provides important information for further modification of pod dehiscence resistance soybean and characterization of soybean pod dehiscence regulation network.