Histopathological studies of soybean – Corynespora cassiicola interaction.

TOULET MARÍA LAURA; NEIRA, DIEGO A.; ESCOBAR MARCELA; TREJO MARÍA FERNANDA; ARIAS MARTA EUGENIA; CASTAGNARO ATILIO PEDRO; CHALFOUN NADIA REGINA

Corrientes

Congreso; V Argentino de Fitopatología , 59th Meeting of the APS Caribbean Division; 2021

Asociación Argentina de Fitopatólogos

Target spot disease caused by the fungus Corynespora cassiicola, is considered one of the main soybean late season diseases in northwestern of Argentina. Resistance genes for this disease have not been described yet and most commercial cultivars are susceptible. ITANOA laboratory has a collection of 241 isolates of the pathogen, from which a subgroup of 24 isolates with different morphological and cultural characteristics, were challenged in the A8000 RG (8.0) cultivar under controlled conditions, identifying different degrees of virulence. In this work, we study the histopathology of the two interactions with most contrasting virulence: a non-virulent isolate that did not produce symptoms and a highly virulent isolate that produced plant death 10 days after infection. Microscopic observations of the tissue infected with the non-virulent isolate, 24 hours after infection (hpi), showed low mycelium development restricted to the upper epidermis, a thickening of the cuticle and of the primary wall in the subepidermal cells, and accumulation of callose in the phloematic vessels. In the tissue infected with the virulent isolate, no thickening of the primary wall was observed, but there was abundant mycelium development at 96 hpi, accompanied by cellular disorganization in the mesophyll cells. These pathogenic and histological studies soybean - C. cassiicola should help understand the genetic basis of the interaction and provide information for better disease management.