Differential expression pattern of an acidic 9/13-lipoxygenase in flower opening and senescence and in leaf response to phloem feeders in the tea plant

Abstract

BackgroundLipoxygenase (LOXs) is a large family of plant enzymes that catalyse the hydroperoxidation of free polyunsaturated fatty acids into diverse biologically active compounds, collectively named phyto-oxylipins. Although multiple isoforms of LOXs have been identified in a wide range of annual herbaceous plants, the genes encoding these enzymes in perennial woody plants have not received as much attention. In Camellia sinensis (L.) O. Kuntze, no LOX gene of any type has been isolated, and its possible role in tea plant development, senescence, and defence reaction remains unknown. The present study describes the isolation, characterization, and expression of the first tea plant LOX isoform, namely CsLOX1, and seeks to clarify the pattern of its expression in the plant's defence response as well as in flower opening and senescence.ResultsBased on amino acid sequence similarity to plant LOXs, a LOX was identified in tea plant and named CsLOX1, which encodes a polypeptide comprising 861 amino acids and has a molecular mass of 97.8 kDa. Heterologous expression in yeast analysis showed that CsLOX1 protein conferred a dual positional specificity since it released both C-9 and C-13 oxidized products in equal proportion and hence was named 9/13-CsLOX1. The purified recombinant CsLOX1 protein exhibited optimum catalytic activity at pH 3.6 and 25°C. Real-time quantitative PCR analysis showed that CsLOX1 transcripts were detected predominantly in flowers, up-regulated during petal senescence, and down-regulated during flower bud opening. In leaves, the gene was up-regulated following injury or when treated with methyl jasmonate (MeJA), but salicylic acid (SA) did not induce such response. The gene was also rapidly and highly induced following feeding by the tea green leafhopper Empoasca vitis, whereas feeding by the tea aphid Toxoptera aurantii resulted in a pattern of alternating induction and suppression.ConclusionsAnalysis of the isolation and expression of the LOX gene in tea plant indicates that the acidic CsLOX1 together with its primary and end products plays an important role in regulating cell death related to flower senescence and the JA-related defensive reaction of the plant to phloem-feeders.

Molecular Landscape of Helopeltis theivora Induced Transcriptome and Defense Gene Expression in Tea

“…Strong early upregulation of LOX and thioesterase genes in 111/1 indicates that TMB triggers synthesis and release of active JA and is probably responsible for most of the woundinduced JA production in the plant. Hemipterans cause significant increase in transcript abundance of LOX in tea and the associated defense reaction (Liu and Han 2010), Arabidopsis and Medicago tranculata (Moran and Thompson 2001;Gao et al 2008), which is a pattern quite similar to our study in the tolerant cultivar (sevenfold upregulation). Likewise, Bu et al (2008) showed that potato NAC domain proteins are induced rapidly and strongly after wounding but not systemically, and their transcript levels reach maximum after 1 h, consistent with our observations.…”

Molecular cloning, characterization and three-dimensional structure prediction of Lipoxygenase from Finger millet [Eleusine coracana (L.) Gaertn.] germinating seedlings

“…Thus EcLOX appears to be up-regulated by MeJA but not by SA. Similar kind of expression of LOX gene was observed in Camellia sinensis (L.) and (CsLOX1) (Liu and Han 2010), in Caragana jubata (CjLOX). Strong up-regulation was observed at 12 h exposure to MeJA (Bhardwaj et al 2011).…”

“…In plants, according to their regio-specificity 9-and 13-LOXs are the two groups of LOXs present, which specifically produce 9-and 13-hydroperoxy fatty acids (Feussner and Wasternack 2002). However, sometimes this classification encounters some difficulties because non-traditional LOXs yield a mixture of 9-and 13-hydroperoxy fatty acids upon catalysis (Liu and Han 2010). Earlier, LOXs were separated into two gene subfamilies type-1 and type-2, according to the absence (type-1) and presence (type-2) of an expected chloroplast transit peptide in their N-terminal side of proteins (Peng et al 1994).…”

Does Enzymatic Hydrolysis of Glycosidically Bound Volatile Compounds Really Contribute to the Formation of Volatile Compounds During the Oolong Tea Manufacturing Process?

“…26 LOX is proposed as a wounding stress-response gene. 25 LOX gene expression level significantly increased at the turn over process ( Figure 5D), which may be one of the reasons that most free fatty acid-derived volatiles and jasmine lactone increased at that process ( Figure 1). Similarly, TPS1, 2, and 3 gene expression levels also significantly increased at the turn over process (Figures 5E,F,G).…”