Examination of the dehiscence zone in soybean pods and isolation of a dehiscence-related endopolygalacturonase gene

Microscopic examination of cross sections of dorsal and ventral sutures of soybean pods (Glycine max cv. TGx1835-2E) at two different stages of maturity revealed that the dehiscence zone of soybean pods is functionally equivalent to the dehiscence zone known from crucifers. Enzymatic assays demonstrated the presence of endo-1,4-beta-glucanases and endopolygalacturonases, the activity of which accumulated in the dehiscence zone and peaked during maturation. A single partial cDNA encoding an endopolygalacturonase was isolated by polymerase chain reaction and this clone was used to isolate the complete gene encoding the endopolygalacturonase in question. Approximately 1.2 kb of 5' upstream sequence was cloned in the plant transformation vector pCAMBIA1301 in front of the uidA (GUS) gene and transformed into Arabidopsis thaliana. Expression analysis of the soybean endopolygalacturonase transcript revealed that the endopolygalacturonase is primarily found in dehiscence-related tissue and is presumably involved in the breakdown of the middle lamella prior to dehiscence. This result was corroborated by GUS stainings of the transgenic Arabidopsis lines.