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Potato virus Y NIa protease activity is not sufficient for elicitation of Ry ‐mediated disease resistance in potato
Author(s) -
Mestre Pere,
Brigneti Gianinna,
Durrant Marcus C.,
Baulcombe David C.
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2003.01917.x
Subject(s) - protease , elicitor , proteolysis , biology , mutant , proteases , virus , ns2 3 protease , potato virus y , potyvirus , virology , biochemistry , enzyme , plant virus , gene
Summary Ry confers extreme resistance (ER) to all strains of potato virus Y (PVY). In previous work, we have shown that the protease domain of the nuclear inclusion a protease (NIaPro) from PVY is the elicitor of the Ry ‐mediated resistance and that integrity of the protease active site is required for the elicitation of the resistance response. Two possibilities arise from these results: first, the structure of the active protease has elicitor activity; second, NIa‐mediated proteolysis is required to elicit the resistance response. To resolve these possibilities, the NIaPro from PVY was randomly mutagenised and the clones obtained were screened for elicitation of cell death as an indicator of resistance and proteolytic activity. We did not find any mutants that had retained the ability to elicit cell death but had lost protease activity, as measured by processing of the NIa cleavage site in the viral genome. This was consistent with the idea that protease activity is necessary for elicitor activity. However, protease activity was not sufficient because we found three elicitor‐defective mutants in which there was a high level of protease activity in this assay.