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Cpkk1, MAPKK of Cryphonectria parasitica, Is Necessary for Virulence on Chestnut

October 2010 , Volume 100 , Number  10
Pages  1,100 - 1,110

Laura Rostagno, Antonio Prodi, and Massimo Turina

First and third authors: Istituto di Virologia Vegetale, CNR, Strada delle Cacce 73, 10135 Torino, Italy; and second author: DISTA, Università di Bologna, Via Fanin 40, 40127 Bologna, Italy.

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Accepted for publication 12 June 2010.

The role of Cpkk1, a mitogen-activated protein kinase from Cryphonectria parasitica, was investigated by generating a number of mutant strains that overexpress, under the control of the cryparin promoter, both the wild-type protein and its allele with an extensive deletion in the catalytic domain. Furthermore, a hairpin construct was built and expressed to cause specific silencing of Cpkk1 mRNA transcripts. Specific mRNA silencing or overexpression was confirmed on both Northern and Western blot analysis. Selected C. parasitica strains with Cpkk1 either silenced or overexpressed were evaluated for their biological characteristics, including virulence on European chestnut, growth on different substrates, conidial sporulation, and resistance to cell-wall-degrading enzymes. Silencing of Cpkk1 and the overexpression of a defective Cpkk1 correlated with a marked reduction in virulence on 3-year-old chestnut trees, with no statistically significant effect on fungal growth in the various conditions tested.

© 2010 The American Phytopathological Society