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Calcium/Calmodulin-Dependent Signaling for Prepenetration Development in Colletotrichum gloeosporioides

January 2003 , Volume 93 , Number  1
Pages  82 - 87

Kwang-Heum Uhm , Il-Pyung Ahn , Soonok Kim , and Yong-Hwan Lee

School of Agricultural Biotechnology, Seoul National University, Suwon 441-744, Korea

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Accepted for publication 12 August 2002.

Colletotrichum gloeosporioides forms a specialized infection structure, an appressorium, for host infection. Contacting hard surface induces appressorium formation in C. gloeosporioides, whereas hydrophobicity of the contact surface does not affect this infection-related differentiation. To determine if the calcium/calmodulin-dependent signaling system is involved in prepenetration morphogenesis in C. gloeosporioides pathogenic on red pepper, effects of calcium chelator (EGTA), phospholipase C inhibitor (neomycin), intracellular calcium modulators (TMB-8 and methoxy verampamil), and calmodulin antagonists (chloroproma-zine, phenoxy benzamine, and W-7) were tested on conidial germination and appressorium formation. Exogenous addition of Ca2+, regardless of concentration, augmented conidial germination, while appressorial differentiation decreased at higher concentrations. Inhibition of appressorium formation by EGTA was partly restored by the addition of calcium ionophore A23187 or CaCl2. Calcium channel blockers and calmodulin antagonists specifically reduced appressorium formation at micromolar levels. These results suggest that biochemical processes controlled by the calcium/calmodulin signaling system are involved in the induction of prepenetration morphogenesis in C. gloeosporioides pathogenic on red pepper.

Additional keywords: anthracnose, Glomerella cingulata .

© 2003 The American Phytopathological Society