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Induction of competence for elicitation of defense responses in cucumber hypocotyls requires proteasome activity
Author(s) -
Becker Jürgen,
Kempf Ralf,
Jeblick Wolfgang,
Kauss Heinrich
Publication year - 2000
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.2000.00677.x
Subject(s) - elicitor , chitinase , proteasome , microbiology and biotechnology , biology , gene expression , plant defense against herbivory , gene , biochemistry
Summary The epidermal cells of hypocotyls from etiolated cucumber seedlings are not constitutively competent for elicitation of the rapid H 2 O 2 defense response. However, elicitor competence developed while conditioning the surface‐abraded seedlings by rotating them in buffer for 4 h. Competence development was greatly potentiated by inducers of systemic acquired resistance and suppressed by specific inhibitors of proteasome activity, clasto ‐lactacystin β‐lactone (LAC) and carboxybenzoyl‐ l ‐leucyl‐ l ‐leucyl‐ l ‐leucinal (LLL). In the freshly abraded seedlings, chitinase gene activation became evident approximately 4 h after elicitor addition. Accumulation of chitinase mRNA was enhanced upon conditioning prior to elicitation and was inhibited by LAC and LLL, indicating that the process which leads to H 2 O 2 elicitation competence is also superimposed on the elicitation of chitinase mRNA. LAC and LLL caused an accumulation of ubiquitin‐conjugated proteins and enhanced the expression of a proteasome α‐subunit, suggesting that proteasome activity was specifically inhibited and that the effect observed on gene expression was not due to impaired gene induction in general. Together, our results suggest that the ubiquitin–proteasome system may play a crucial role in a process which switches the signaling pathway for diverse plant defense responses into a functional state, as is known for many basic cellular processes in both animals and yeast.