Dual positional specificity and expression of non-traditional lipoxygenase induced by wounding and methyl jasmonate in maize seedlings.
Lipoxygenases (LOXs) catalyze the formation of fatty acid hydroperoxides involved in responses to stresses. This study examines the expression of a non-traditional dual positional specific maize LOX in response to wounding or methyl jasmonate (MeJA). Full-length maize LOX cDNA was expressed in Escherichia coli, and recombinant LOX was purified and characterized enzymatically. RP-HPLC and GC-MS analysis showed that the purified LOX converts alpha-linolenic acid into 13-hydroperoxylinolenic acid and 9-hydroperoxylinolenic acid in a 6:4 ratio. LOX mRNA accumulated rapidly and transiently in response to wounding reaching a peak of expression about 3 h after wounding. This increase followed an initial increase in endogenous jasmonic acid (JA) 1 h after wounding (JA burst). However, the expression of LOX induced by MeJA lasted longer than the expression induced by wounding, and the MeJA-induced expression seemed to be biphasic pattern composed of early and late phases. The expression of LOX in the presence of inhibitors of JA biosynthesis was not completely inhibited, but delayed in wound response and the expression period was shortened in MeJA response. These results suggest that wound-responsive JA burst may trigger the early phase of LOX expression which facilitates biosynthesis of endogenous JA through its 13-LOX activity, and subsequently leads to the activation of the late phase LOX expression in MeJA-treated maize seedlings. Implications of dual positional specificity of maize LOX in the observed expression kinetics are discussed.
Kim
Eun-Seon
ES
Department of Applied Biotechnology, Agricultural Plant Stress Research Center, and Biotechnology Research Institute, Chonnam National University, Kwangju 500-757, Republic of Korea.
Choi
Eunyoung
E
Kim
Youngsun
Y
Cho
Kyoungwon
K
Lee
Ayoung
A
Shim
Jaehan
J
Rakwal
Randeep
R
Agrawal
Ganesh Kumar
GK
Han
Oksoo
O
D000085:Acetates / Q000494:pharmacology*; D000595:Amino Acid Sequence; D001241:Aspirin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology*; D008401:Gas Chromatography-Mass Spectrometry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008084:Lipoxygenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008969:Molecular Sequence Data; D054883:Oxylipins; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D036226:Seedlings / Q000201:enzymology / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013314:Stress, Mechanical; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013997:Time Factors; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*
D000085:Acetates; D003517:Cyclopentanes; D016859:Lipoxygenase Inhibitors; D054883:Oxylipins; D010937:Plant Growth Regulators; D011720:Pyrazoles; C011006:jasmonic acid; C072239:methyl jasmonate; D008084:Lipoxygenase; C015429:phenidone; D001241:Aspirin