Affiliation:
1. Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto Prefectural University, Kyoto 606-8522, Japan
Abstract
ABSTRACT
Kelch repeat proteins are important mediators of fundamental cellular functions and are found in diverse organisms. However, the roles of these proteins in filamentous fungi have not been characterized. We isolated a kelch repeat-encoding gene of
Colletotrichum lagenarium ClaKEL2
, a
Schizosaccharomyces pombe tea1
homologue. Analysis of the
clakel2
mutant indicated that
ClaKEL2
was required for the establishment of cellular polarity essential for proper morphogenesis of appressoria and that there is a plant signal-specific bypass pathway for appressorium development which circumvents
ClaKEL2
function. Clakel2p was localized in the polarized region of growing hyphae and germ tubes, and the localization was disturbed by a microtubule assembly blocker. The
clakel2
mutants formed abnormal appressoria, and those appressoria were defective in penetration hypha development into cellulose membranes, an artificial model substrate for fungal infection. Surprisingly, the
clakel2
mutants formed normal appressoria on the host plant and retained penetration ability. Normal appressorium formation on the artificial substrate by the
clakel2
mutants was restored when cells were incubated in the presence of CaCl
2
or exudates from cucumber cotyledon. Furthermore, calcium channel modulators inhibited restoration of normal appressorium formation. These results suggest that there could be a bypass pathway that transduces a plant-derived signal for appressorium development independent of
ClaKEL2
and that a calcium signal is involved in this transduction pathway.
Publisher
American Society for Microbiology
Subject
Molecular Biology,General Medicine,Microbiology
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