Antisense expression of the calmodulin gene from Colletotrichum trifolii impairs prepenetration development

Calmodulin is a ubiquitous highly conserved calcium binding protein involve d in cell signalling. Previous studies in our laboratory suggested a role f or calmodulin in prepenetration morphogenesis in Colletotrichum trifolii, t he causal agent of alfalfa anthracnose. In this report, we describe the clo ning, sequencing and partial characterization of the calmodulin gene from C . trifolii. The gene is present as a single copy in the genome of C. trifol ii and its predicted amino acid sequence shows considerable homology to oth er fungal calmodulins. The gene is most highly expressed during conidial ge rmination and appressorial development. Using a Neurospora crassa inducible promoter driving the calmodulin gene in antisense orientation, transforman ts were obtained with constitutive levels of antisense calmodulin expressio n. Upon induction, transformants did not develop appressoria and were not p athogenic on alfalfa plants. (C) 2000 Federation of European Microbiologica l Societies. Published by Elsevier Science B.V. All rights reserved.