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Dynamic hydrolase activities precede hypersensitive tissue collapse in tomato seedlings
Author(s) -
Sueldo Daniela,
Ahmed Ali,
MisasVillamil Johana,
Colby Tom,
Tameling Wladimir,
Joosten Matthieu H. A. J.,
Hoorn Renier A. L.
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12870
Subject(s) - hypersensitive response , apoplast , proteases , biology , cell wall , biochemistry , hydrolase , plant defense against herbivory , deubiquitinating enzyme , enzyme , programmed cell death , carboxypeptidase , serine , serine hydrolase , microbiology and biotechnology , ubiquitin , apoptosis , gene
Summary Hydrolases such as subtilases, vacuolar processing enzymes ( VPE s) and the proteasome play important roles during plant programmed cell death ( PCD ). We investigated hydrolase activities during PCD using activity‐based protein profiling ( ABPP ), which displays the active proteome using probes that react covalently with the active site of proteins. We employed tomato ( S olanum lycopersicum ) seedlings undergoing synchronized hypersensitive cell death by co‐expressing the avirulence protein Avr4 from C ladosporium fulvum and the tomato resistance protein Cf‐4. Cell death is blocked in seedlings grown at high temperature and humidity, and is synchronously induced by decreasing temperature and humidity. ABPP revealed that VPE s and the proteasome are not differentially active, but that activities of papain‐like cysteine proteases and serine hydrolases, including Hsr203 and P69B, increase before hypersensitive tissue collapse, whereas the activity of a carboxypeptidase‐like enzyme is reduced. Similar dynamics were observed for these enzymes in the apoplast of tomato challenged with C . fulvum . Unexpectedly, these challenged plants also displayed novel isoforms of secreted putative VPE s. In the absence of tissue collapse at high humidity, the hydrolase activity profile is already altered completely, demonstrating that changes in hydrolase activities precede hypersensitive tissue collapse.