Microscopic study of Alternaria brassicae infection processes in Brassica juncea cultivars by drop plus agarose method

Abstract

Alternaria blight caused by Alternaria brassicae (Berk) Sacc. is one of the most serious diseases of Indian mustard [Brassica juncea (L.) Czern and Coss.] grown as edible oilseed crop in India. Poorly characterized tolerance mechanisms against this pathogen further confirm the strategies that can be undertaken to design durable resistance or effective disease control measures. The host-pathogen interaction was studied and showed that the initial infection processes involving conidium germination and mode of penetration were similar in both cultivars, although considerably late in ‘PAB 9511’ evidently due to tolerance. However, apparent differences between the two cultivars were noticeable by 1 dpi. At the plant surface, impeded fungal growth, less proliferation of spores and active suppression of the dense hyphal moulds are the factors involved in the expression of tolerance against A. brassicae in cultivar PAB 9511. Our findings have notably advanced our understanding of the mechanism of tolerance in this patho-system.   Key words: Artificial inoculation, Brassica juncea, Alternaria brassicae, pathogenicity,plant-pathogen interaction.