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Antagonistic role of 9‐lipoxygenase‐derived oxylipins and ethylene in the control of oxidative stress, lipid peroxidation and plant defence
Author(s) -
López Miguel A.,
Vicente Jorge,
Kulasekaran Satish,
Vellosillo Tamara,
Martínez Marta,
Irigoyen Maria L.,
Cascón Tomas,
Bannenberg Gerard,
Hamberg Mats,
Castresana Carmen
Publication year - 2011
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 - 10.1111/j.1365-313x.2011.04608.x
Subject(s) - lipid peroxidation , lipoxygenase , mutant , ethylene , oxylipin , chemistry , biochemistry , oxidative stress , salicylic acid , singlet oxygen , inducer , pseudomonas syringae , fatty acid , malondialdehyde , oxygen , enzyme , gene , organic chemistry , catalysis
Summary 9‐lipoxygenases (9‐LOXs) initiate fatty acid oxygenation in plant tissues, with formation of 9‐hydroxy‐10,12,15‐octadecatrienoic acid (9‐HOT) from linolenic acid. A lox1 lox5 mutant, which is deficient in 9‐LOX activity, and two mutants noxy6 and noxy22 ( non‐responding to oxylipins ), which are insensitive to 9‐HOT, have been used to investigate 9‐HOT signalling. Map‐based cloning indicated that the noxy6 and noxy22 mutations are located at the CTR1 (CONSTITUTIVE ETHYLENE RESPONSE1) and ETO1 (ETHYLENE‐OVERPRODUCER1) loci, respectively. In agreement, the noxy6 and noxy22 mutants, renamed as ctr1‐15 and eto1‐14 , respectively, showed enhanced ethylene (ET) production. The correlation between increased ET production and reduced 9‐HOT sensitivity indicated by these results was supported by experiments in which exogenously added ethylene precursor ACC (1‐aminocyclopropane‐1‐carboxylic acid) impaired the responses to 9‐HOT. Moreover, a reciprocal interaction between ET and 9‐HOT signalling was indicated by results showing that the effect of ACC was reduced in the presence of 9‐HOT. We found that the 9‐LOX and ET pathways regulate the response to the lipid peroxidation‐inducer singlet oxygen. Thus, the massive transcriptional changes seen in wild‐type plants in response to singlet oxygen were greatly affected in the lox1 lox5 and eto1‐14 mutants. Furthermore, these mutants displayed enhanced susceptibility to both singlet oxygen and Pseudomonas syringae pv. tomato , in the latter case leading to increased accumulation of the lipid peroxidation product malondialdehyde. These findings demonstrate an antagonistic relationship between products of the 9‐LOX and ET pathways, and suggest a role for the 9‐LOX pathway in modulating oxidative stress, lipid peroxidation and plant defence.