Identifying F. oxysporum Strains Causing Wilt in Southern Indian Chickpeas

Abstract

Fusarium oxysporum (Schletend: Fr) f. sp. ciceri (Padwick), referred to as Foc, is a soil-borne fungus that poses a constant threat to chickpeas (Cicer arietinum L.) by causing wilt disease. Typical wilt symptoms were observed in chickpea plants collected from 24 different locations across three southern Indian states. The process involved isolating Fusarium species from the roots of these wilted plants, resulting in the identification of various strains exhibiting diverse cultural and morphological characteristics on potato dextrose agar medium. All twenty four isolates were subjected to Koch's postulates using the standard method, which yielded varied responses in terms of disease incidence. After analyzing cultural, morphological, molecular traits, and conducting pathogenicity tests, the fungus was definitively identified as F. oxysporum Schlechtend. Fr. f. sp. ciceri (Padwick) Matuo and K. Sato. Among the 24 isolates tested on the chickpea wilt susceptible cultivar JG-62, one was non-pathogenic with zero percent disease incidence (PDI), while one isolate was highly pathogenic showed 100 percent PDI. Highly pathogenic four isolate was further used for molecular identification with secreted in xylem primers (SIX). Comparative studies of cultural traits and conidial morphology among different isolates revealed variations in growth patterns, pigmentation, sporulation, and the size and structure of macro and micro conidia, as well as chlamydospores.