Responses of phospholipase D and lipoxygenase to mechanical wounding in postharvest cucumber fruits

Abstract

Abstract:This study was to investigate the responses of phospholipase D (PLD) and lipoxygenase (LOX) to mechanical wounding in postharvest cucumber (Cucumis sativus L. cv. Biyu-2) fruits. Membrane-associated Ca 2+ content, activities and gene expression of PLD and LOX, and contents of phosphatidylcholine (PC), phosphatidylinositol (PI), and phosphatidic acid (PA) were determined in cucumber fruits following mechanical wounding. Results show that PLD and LOX activities increased with the PLD and LOX mRNAs which are upregulated upon wounding, while membrane-associated Ca 2+ content decreased. Accompanying with the increase of PLD and LOX activities, accumulation of PA and losses of PC and PI were observed in all fruits, but there were differences of degrees between wounded and control fruits. Results suggest that PLD and LOX might be the main hydrolytic enzymes of phospholipids in postharvest cucumber fruits participating in the mechanical wounding injury. The activation of PLD and LOX might be the result of gene expression, which could be stimulated by the Ca 2+ flowing from the membrane to the cytoplasm upon receiving the wounding signals.

Responses of Phospholipase D and Antioxidant System to Mechanical Wounding in Postharvest Banana Fruits

“…Much higher LOX activity was observed in wounded fruits than that in control throughout the entire storage period. Similar results were obtained by Zhao et al who reported that LOX might be the main hydrolytic enzymes of phospholipids in response to mechanical wounding in postharvest cucumber fruits [8].…”

“…In castor bean leaves, it has been reported that free fatty acid quantity and PLD activity increase with wounding. Increases in membrane-associated PLD and LOX have been observed in response to mechanical wounding in postharvest cucumber fruits [8].…”

“…LOX, encoding a lipoxygenase involved in jasmonate (wounding-induced signaling molecule) synthesis, is transcriptionally upregulated in response to wounding in Arabidopsis [7]. It has been proposed that the liberated polyunsaturated fatty acids serve as substrates for LOX that produces activated oxygen and lipid peroxides leading to membrane damage [8]. PLD has been proposed to play several roles in wounding response.…”

Role of antioxidative system during the development and senescence of cucumber fruit

“…Primer sequences are shown in Table 1. 18S ribosomal RNA (18S rRNA) gene of C. sativus was used as a housekeeping gene (Zhao et al 2010), and immature cucumber fruit was set as control. All operations were followed the method of Zhao et al (2010).…”

“…a -GenBank accession number according to the National Center for Biotechnology Information (NCBI) database; b -according to referenceZhao et al (2010).…”