Disease reaction of chickpea (Cicer spp.) genotypes to Botrytis grey mould (Botrytis cinerea)

Abstract

Screening and identification of disease resistance to Botrytis grey mould (BGM, Botrytis cinerea) of chickpea is an important component to the development of integrated disease management strategies. The disease reaction to BGM with C. arietinum genotypes and C. bijugum accessions were assessed in growth chamber bioassays. The infection typically progressed with more severe necrosis and wilting from the shoot tip that could spread at least 2–4 internodes with the most susceptible reaction resulting in plant collapse and death. Fungal mycelium was commonly observed growing externally on shoot tips and sporulation occurred within 7–14 days. Initial screening to evaluate the disease progression from C. arietinum genotypes and C. bijugum accessions showed that disease symptoms were indicative of severity and increased with time. Moderate resistance was detected in four C. arietinum genotypes 99314–1003, FLIP97-529C, FLIP94-089C, FLIP94-508C and all six C. bijugum accessions. A detached leaf assay was effective in discriminating resistance in C. bijugum ILWC240 and susceptibility in FLIP97-90C and Lasseter genotypes, based on lesion number per leaflet. The detached leaf assay could be used for screening susceptible genotypes in less time than growth chamber bioassays. Resistance in C. bijugum indicated the potential use of wild Cicer species for novel sources of BGM resistance. Microscopic examination of the initial infection process with whole leaflet sections showed spore germination, appressoria formation as hyphal tip swelling and penetration directly through the cuticle, stomata and glandular stalks on the leaf surface. However, no remarkable differences between resistant and susceptible genotypes were shown within 72 h after inoculation (hai). This indicated that defence responses were likely to have been effective after 72 hai during the post-penetration or colonisation phase.