Duplicate maize 13-lipoxygenase genes are differentially regulated by circadian rhythm, cold stress, wounding, pathogen infection, and hormonal treatments

Abstract

Most plant oxylipins, a large class of diverse oxygenated polyunsaturated fatty acids and their derivatives, are produced through the lipoxygenase (LOX) pathway. Recent progress in dicots has highlighted the biological roles of oxylipins in plant defence responses to pathogens and pests. By contrast, the physiological function of LOXs and their metabolites in monocots is poorly understood. Two maize LOXs, ZmLOX10 and ZmLOX11 that share >90% amino acid sequence identity but are localized on different chromosomes, were cloned and characterized. Phylogenetic analysis revealed that ZmLOX10 and ZmLOX11 cluster together with well-characterized plastidic type 2 linoleate 13-LOXs from diverse plant species. Regio-specificity analysis of recombinant ZmLOX10 protein overexpressed in Escherichia coli proved it to be a linoleate 13-LOX with a pH optimum at approximately pH 8.0. Both predicted proteins contain putative transit peptides for chloroplast import. ZmLOX10 was preferentially expressed in leaves and was induced in response to wounding, cold stress, defence-related hormones jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA), and inoculation with an avirulent strain of Cochliobolus carbonum. These data suggested a role for this gene in maize adaptation to abiotic stresses and defence responses against pathogens and pests. ZmLOX11 was preferentially expressed in silks and was induced in leaves only by ABA, indicating its possible involvement in responses to osmotic stress. In leaves, mRNA accumulation of ZmLOX10 is strictly regulated by a circadian rhythm, with maximal expression coinciding temporally with the highest photosynthetic activity. This study reveals the evolutionary divergence of physiological roles for relatively recently duplicated genes. Possible physiological functions of these 13-LOXs are suggested.

UV-B Inhibits Leaf Growth through Changes in Growth Regulating Factors and Gibberellin Levels

“…S2). Cluster XII, which includes transcripts that show low expression levels under control conditions but are highly induced by UV-B in all three segments, comprises TASSEL SEED1, which encodes a lipoxygenase involved in the synthesis of jasmonate in maize (Nemchenko et al, 2006); and cluster XX, with a very similar expression pattern to cluster XII, comprises a TCP transcription factor that also could participate in the regulation of leaf development (Koyama et al, 2010). These or other transcripts in the three clusters may be involved in the repression of the expression of transcripts in clusters I, II, IV, V, and XIII, which may be necessary for cell division in the DEZ.…”

Genome-Wide Expression Profiling Arabidopsis at the Stage ofGolovinomyces cichoracearumHaustorium Formation

“…Light influences host cellular processes, such as the photosynthetic activity, antioxidant defenses, carbohydrate catabolism among others, and it is likely that these processes may be affected by fungal infection. Genes sensitive to both, light and pathogens, have been characterized in several species including those encoding for ascorbate peroxidase from rice (Oryza sativa; Agrawal et al, 2003), lipoxygenase from maize (Zea mays; Nemchenko et al, 2006), and DEA1 from tomato (Solanum lycopersicum; Weyman et al, 2006).…”

Regulation of Pathogenesis by Light in Cercospora zeae-maydis: An Updated Perspective

“…In maize leaves, the oxylipin encoding gene, ZmLOX10, is primarily regulated by circadian rythmicity (Nemchenko et al, 2006). Significantly, ZmLOX10 expression parallels the diurnal increase in photosynthesis activity (Nemchenko et al, 2006). This suggests that light may be a key factor involved in the induction of host defense regulators, such as oxylipins, in response to circadian rythmicity.…”

“…In the context of this review, oxylipins are most notable as potent regulators of host defense in response to fungal pathogens (Farmer et al, 2003;Prost et al, 2005;Rosahl and Feussner, 2004). In maize leaves, the oxylipin encoding gene, ZmLOX10, is primarily regulated by circadian rythmicity (Nemchenko et al, 2006). Significantly, ZmLOX10 expression parallels the diurnal increase in photosynthesis activity (Nemchenko et al, 2006).…”