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Isolation and characterization of signal transduction mutants of Arabidopsis thaliana that constitutively activate the octadecanoid pathway and form necrotic microlesions
Author(s) -
Hilpert Bernadette,
Bohlmann Holger,
Den Camp Roel op,
Przybyla Dominika,
Miersch Otto,
Buchala Anthony,
Apel Klaus
Publication year - 2001
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.2001.2641036.x
Subject(s) - jasmonic acid , mutant , biology , oxylipin , salicylic acid , arabidopsis thaliana , arabidopsis , gene , signal transduction , abscisic acid , r gene , biochemistry , microbiology and biotechnology , plant disease resistance
Summary Thionins are a group of antimicrobial polypeptides that form part of the plant's defense mechanism against pathogens. The Thi 2.1 thionin gene of Arabidopsis thaliana has been shown to be inducible by jasmonic acid (JA), an oxylipin‐like hormone derived from oxygenated linolenic acid and synthesized via the octadecanoid pathway. The JA‐dependent regulation of the Thi 2.1 gene has been exploited for setting up a genetic screen for the isolation of signal transduction mutants that constitutively express the Thi 2.1 gene. Ten cet ‐mutants have been isolated which showed a c onstitutive e xpression of the t hionin gene. Allelism tests revealed that they represent at least five different loci. Some mutants are dominant, others recessive, but all cet mutations behaved as monogenic traits when backcrossed with Thi 2.1‐ GUS plants. Some of the mutants overproduce JA and its bioactive precursor 12‐oxophytodienoic acid (OPDA) up to 40‐fold while others have the same low levels as the control wildtype plants. Two of the mutants showed a strong induction of both the salicylic acid (SA)‐ and the JA‐dependent signaling pathways, while the majority seems to be affected only in the octadecanoid pathway. The Thi 2.1 thionin gene and the Pdf 1.2 defensin gene are activated independently, though both are regulated by JA. The cet ‐mutants, except for one, also show a spontaneous leaf cell necrosis, a reaction often associated with the systemic acquired resistance (SAR) pathway.