Dual positional specificity and expression of non-traditional lipoxygenase induced by wounding and methyl jasmonate in maize seedlings

Abstract

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.

Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid

“…We further examined whether these elevated levels of JA contribute to enhanced resistance to CLA. qRT-PCR was used to monitor the expression of LOX1 and 12-oxo-phytodienoic acid reductase8 (OPR8), two key genes involved in JA biosynthesis in maize (Kim et al, 2003;Yan et al, 2012). Previously, it was shown that fall armyworm feeding significantly induced the expression of JA biosynthesis genes in Mp708 compared with the Tx601 plants (Shivaji et al, 2010).…”

Purification and properties of lipoxygenase from opium poppy seedlings(Papaver somniferum L.)

“…Several plant LOXs exhibiting dual positional specificity are classified as nontraditional LOX enzymes. These LOXs can produce a wider range of final products in a lipoxygenase pathway than strictly 13-LOX or 9-LOX and might have more diverse physiological functions (Kim et al, 2003;Wang et al, 2003;Cho et al, 2011). Knowledge of the biochemical features of LOXs in different plant species is necessary for classification of these enzymes and might help to elucidate their corresponding cellular roles.…”

“…Knowledge of the biochemical features of LOXs in different plant species is necessary for classification of these enzymes and might help to elucidate their corresponding cellular roles. LOX characterized in maize seedlings with dual positional specificity had a role in pathogen and wound stress responses (Kim et al, 2003). In cucumber seedlings 13-LOX, a special linoleate that is involved in the initial stages of lipid mobilization during germination, was detected.…”

Methyl Jasmonate Elicitation Affects Expression of Genes Involved in Biosynthesis and Turnover of 2-Phenylethylamine in Maize Seedlings

“…The present study showed that exogenous MJ vapors led to substantial increases in LOX transcript amounts in both roots and leaves of Z. mays seedlings. Kim et al (2003) identified the biphasic pattern of upregulation of the LOX gene expression (two peaks of LOX transcript accumulation at 6 and 24 h, respectively) in the maize seedlings exposed to MJ treatment. Similarly, Concha et al (2013) also elucidated considerable increments in the levels of LOX gene expression in fruits of Fragaria chiloensis L.…”

“…The majority of lipoxygenases (LOXs; EC 1.13.11.12) comprise non-heme and iron-containing dioxygenases responsible for oxygenation of polyunsaturated fatty acids to the corresponding hydroperoxides (Kim et al, 2003). Diverse physiological functions of these enzymes also include involvement in the biosynthetic route of jasmonates (Gharechahi et al, 2013).…”