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Cel1, Probably Encoding a Cellobiohydrolase Lacking the Substrate Binding Domain, Is Expressed in the Initial Infection Phase of Claviceps purpurea on Secale cereale

March 1997 , Volume 10 , Number  2
Pages  268 - 279

Ulrike Müller , Klaus B. Tenberge , Birgitt Oeser , and Paul Tudzynski

Institut für Botanik, Westfälische Wilhelms-Universität, Schloßgarten 3, D-48149 Münster, Germany

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Accepted 12 November 1996.

At the host-pathogen interface of hyphae penetrating host cell walls in the rye ovary, a lack of cellulase-gold labeling of β-1,4-glucan in host cell walls indicates that enzymatic degradation of cellulose might be an important factor during the infection of rye by Claviceps purpurea. Using cbhI from Trichoderma reesei as a probe, a putative cellulase gene (cel1) was isolated from a genomic library of the C. purpurea strain T5. The coding region of 1,616 bp contains two introns and a putative signal peptidase cleavage site, leaving a coding capacity of 437 amino acids for the mature protein. The derived amino acid sequence shares significant homology with other fungal cellobiohydrolases and lacks the substrate binding domain. Expression analysis using reverse transcriptase-polymerase chain reaction (RT-PCR) shows that cel1 is induced during the first days of infection of rye by C. purpurea. It may be involved in the penetration and degradation of host cell walls by depolymerizing plant β-1,4-glucan and, therefore, play a role in the infection process.

Additional keywords: enzyme-gold localization, fungal cellulase, gene expression, host-pathogen interaction, molecular cloning.

© 1997 The American Phytopathological Society