Histopathology of red crown rot of soybean

Histopathological analyses of red crown rot (RCR) of soybean were performed using field-grown and indoor-grown soybean plants. These analyses revealed that soybean plants formed a periderm to prevent pathogen invasion. When a break formed in the periderm, an additional periderm newly differentiated into the inner cells and prevented pathogen invasion. If the pathogen reached the intravascular tissues, some xylem parenchyma cells died, and the vessels were occluded by gum. Periderm formation and vessel occlusion were observed not only in slightly diseased soybean plants, but also in seriously diseased plants, indicating that both reactions function as part of the defense response against RCR.