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A Cysteine Protease Gene Is Expressed Early in Resistant Potato Interactions with Phytophthora infestans

December 1999 , Volume 12 , Number  12
Pages  1,114 - 1,119

Anna O. Avrova , Helen E. Stewart , Walter De Jong , Jacqueline Heilbronn , Gary D. Lyon , and Paul R. J. Birch

Departments of Fungal and Bacterial Plant Pathology and of Crop Genetics, Scottish Crop Research Institute (SCRI), Invergowrie, Dundee, DD2 5DA, U.K.

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Accepted 3 September 1999.

A potato cysteine protease (cyp) cDNA expressed at an early stage of an incompatible interaction with Phytophthora infestans was isolated. Both the nucleotide and deduced amino acid sequences are highly homologous to those of a tomato cysteine protease, CYP1. Striking protein similarity to all known cathepsins in animals, particularly cathepsin K, was also observed. However, unlike cathepsins, a granulin binding domain is located near the carboxyl terminus of the putative CYP protein. In animals, granulins bind to receptors in the plasma membrane and signal cell growth and division. A ribonuclease protection assay demonstrated that the cyp gene is tightly regulated and is induced 15 h post inoculation with P. infestans in potato leaves either with high field resistance or in which a resistance (R) gene is activated. We conclude that a common signaling pathway is activated in each form of resistance.

Additional keywords: hypersensitive response, programmed cell death.

© 1999 The American Phytopathological Society