B. Sneh, M. Ichielevich-Auster
The hypovirulent (HV) isolate (No. 521) densely colonized the outer surface of the hypocotyls and roots of radish and cotton seedlings but did not penetrate into the cortical parenchyma, whereas the virulent (V) isolate (No. 82) penetrated the root and hypocotyl tissues (except for the xylem vessels) to the center of the pith parenchyma. The HV isolate did not cause any degradation of the cell wall material except for the cuticular layer that had disappeared in the regions of close contact between the hyphae and the epidermal outer surface. During the prepenetration stages of the V isolate, the cell walls of the seedlings underwent a significant, visible degradation. The cuticle between the hyphae and the epidermis was detached and degraded. The HV isolate seems to densely cover the outer surface of the seedlings, and it may occupy the possible infection sites, rendering recognition and occupation of such sites unavailable for the virulent pathogen.
B. Sneh, M. Ichielevich-Auster
The hypovirulent (HV) isolate (No. 521) densely colonized the outer surface of the hypocotyls and roots of radish and cotton seedlings but did not penetrate into the cortical parenchyma, whereas the virulent (V) isolate (No. 82) penetrated the root and hypocotyl tissues (except for the xylem vessels) to the center of the pith parenchyma. The HV isolate did not cause any degradation of the cell wall material except for the cuticular layer that had disappeared in the regions of close contact between the hyphae and the epidermal outer surface. During the prepenetration stages of the V isolate, the cell walls of the seedlings underwent a significant, visible degradation. The cuticle between the hyphae and the epidermis was detached and degraded. The HV isolate seems to densely cover the outer surface of the seedlings, and it may occupy the possible infection sites, rendering recognition and occupation of such sites unavailable for the virulent pathogen.