Colonization of maize roots by Colletotrichum graminicola

García,V.M., Thon, M.R. and Sukno, S.A. 2006.  8th European Conference on Fungal Genetics (ECFG). Vienna, Austria. April 7-12, 2006.

Colletotrichum graminicola (Ces.) G. W. Wils. causes anthracnose stalk rot, top 

die-back and leaf blight of maize. The pathogen survives in residue on the soil 

surface, in buried residue, and as sclerotia (stromata) inside stems on the soil. 

Little is known about its role as a root pathogen though it has been suggested 

that C. graminicola can infect maize roots in the field. Recent literature suggests 

that many fungi that are commonly regarded as causal agents of foliar diseases 

can also cause systemic infection of their hosts by invading roots. We are 

investigating the importance of root infections of C. graminicola on the 

anthracnose disease cycle. Maize seeds were grown in vermiculite that had been 

inoculated with mycelial agar plugs of C. graminicola isolate M1.001BH. Three 

weeks after sowing, the roots of the seedlings were washed, sectioned, and 

visualized with light and fluorescent microscopy. Lesions on the roots were not 

observed, however fungal hyphae could be found colonizing the surface of the 

roots and invading epidermal cortex and vascular tissue. Structures, typically 

formed by root pathogens but not previously reported for C. graminicola on 

roots, including hyphopodia and microsclerotia were observed. Certain epidermal 

and cortical cells become infected from intercellular hyphae while surrounding 

cells are uninfected, resulting in a mosaic pattern of infection. Interestingly, 

conidia were formed in acervuli on the root surfaces but were also found filling 

epidermal cells and root hairs. Preliminary data indicate that root infections 

cause significant stunting of both roots and above ground portions of seedlings 

and that the fungus can spread from the roots to aerial tissues. These 

observations suggest that root infection may be an important component of the 

maize anthracnose disease cycle. 

 

 

Poster

 

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