Arthrospores Production in Colletotrichum gloeosporioides from Onion under Nutrient-depleted Conditions
Ram Dutta *
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
Jayalakshmi K *
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
Satish Kumar
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
Radhakrishna A
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
Vishal S Gurav
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
Vijay Mahajan
ICAR-Directorate of Onion and Garlic Research, Pune-410505, Maharashtra, India.
*Author to whom correspondence should be addressed.
Abstract
Colletotrichum gloeosporioides, a well-known anthracnose-causing pathogen, primarily reproduces asexually through conidia. However, the formation of Arthrospores, a less-characterized survival structures, was observed under nutrient-depleted conditions in C. gloeosporioides isolated from onion. The fungus was grown on PDA and identified through molecular characterization using the ITS1/ITS4 and tef1-α gene regions. Arthrospores production was notably associated with distinct morphological changes in the colony, particularly in cultures aged 18 days under nutrient-depleted conditions, indicating that environmental stress may act as a trigger for arthrospore formation. Light microscopy revealed hyphal fragmentation into thick-walled, rectangular Arthrospores distinct from the typical fusiform conidia. This study presents morphological evidence of arthrospore formation in C. gloeosporioides, potentially contributing to its survival and persistence in field environments. These findings highlight a novel adaptation mechanism in this pathogen which has potential implications for disease epidemiology and management.
Keywords: Colletotrichum gloeosporioides, onion anthracnose, arthrospores, hyphal fragmentation, nutrient stress, fungal survival