Greater Anatomical Differences of Pod Ventral Suture in Shatter‐Susceptible and Shatter‐Resistant Soybean Cultivars

ABSTRACT Fruit dehiscence or seed dispersion is an essential process in the proliferation of wild plants, but it is one of the major factors leading to significant yield losses in domesticated soybean. The ventral suture is critical to pod dehiscence in soybean. To better understand the anatomy of the ventral suture in the soybean pod, we compared the dehiscence zone (DZ) and vascular bundle anatomical structure of the ventral suture using three shatter‐susceptible soybean [Glycine max (L.) Merr.] cultivars and three shatter‐resistant soybean cultivars, which had been evaluated from 140 cultivars over two growing seasons. We found that shatter‐susceptible cultivars, in the cross‐sections of ventral sutures, had a larger vascular bundle area and bundle cap area. The cells of bundle caps in shatter‐susceptible cultivars were even in shape and arranged more closely with less interstitial substance. There was a significantly shorter and straight route from the top of fiber cap cells to the connecting point of the two valves of the pod ventral suture in shatter‐susceptible cultivars than in shatter‐resistant soybean cultivars. Our findings suggest that the route from the top of fiber cap cells to the connecting point of the two valves, the vascular bundle area, the bundle cap area, and the cell arrangement in the bundle cap might be a partial mechanism involved in pod dehiscence of soybean.