GmTGA9-GmDYT1 Regulates Anther Wall Development to Affect Male Fertility in Soybean

The scarcity of nuclear male-sterile (NMS) lines severely constrains the development of hybrid breeding in soybean. This study highlights the important role of a conserved GmTGA9-GmDYT1 regulatory module in controlling soybean anther development and male fertility. Through CRISPR/Cas9-mediated screening of the four TGA9 genes in soybean, we discovered that GmTGA9c and GmTGA9d may be involved in male fertility. The tga9d single-gene mutation caused abnormal thickening of the anther middle layer and impeded anther dehiscence, resulting in partial male sterility. We then found that GmTGA9d directly bound to and inhibited its downstream target gene, GmDYT1c. Furthermore, genetic evidence supports that GmDYT1a and GmDYT1c have functionally overlapping roles. Mutation of both genes caused aberrant degradation of the anther middle layer and tapetum, interrupting microspore development and resulting in complete male sterility. This study provides evidence that the GmTGA9-GmDYT1 pathway in soybean plays important roles in regulating male sterility by controlling the development of the anther wall. These findings provide novel mechanistic insights for research on and application of NMS materials in soybean heterosis utilization and hybrid breeding.