Comparison of histological and physiological responses to Phakopsora pachyrhizi in resistant and susceptible soybean

Abstract

Although cuticular and epidermal penetration by the rust and death of the penetrated cell were similar in two cultivars, subsequent hyphal branching and growth was decreased and retention of trypan blue stain was increased in the resistant cultivar. No uredinia formed in the resistant cultivar. Phytoalexin formation began earlier in the resistant cultivar and at a time when many cells had changed in their physiology as revealed by stain retention. A product of germinating urediniospores caused more rapid browning and phytoalexin formation in pods of the resistant cultivar.