Abstract: The effects of 1-methylcyclopropene (1-MCP) on ascorbate (AsA) metabolism were studied and the possible molecular mechanisms were discussed for two cultivars of cauliflower (Brassica oleracea, L. var. botrytis), ‘Violet Queen’ and ‘Snow Crown’. Ethylene production was suppressed in ‘Violet Queen’, while it was increased in ‘Snow Crown’ by 1-MCP treatment. Meanwhile, the changing patterns of AsA metabolism after harvest were different between the two cauliflower cultivars. In ‘Violet Queen’, AsA content decreased in the control after harvest, and the loss of AsA was delayed by 1-MCP treatment. In ‘Snow Crown’, AsA content remained almost constant and was not affected by 1-MCP treatment. In ‘Violet Queen’, the gene expression of BO-APX1, BO-APX2, and BO-sAPX was down-regulated, while the gene expression of BO-DHAR and BO-GLDH was up-regulated by 1-MCP treatment. The regulation of these genes contributed to the suppression of AsA reduction in ‘Violet Queen’ treated by 1-MCP. In ‘Snow Crown’, simultaneous down-regulation of BO-APX1, BO-APX2, and BO-sAPX, which were responsible for AsA breakdown, and BO-MDAR1, BO-MDAR2, BO-DHAR, and BO-GLDH, which were responsible for AsA regeneration and biosynthesis, might lead to maintain the AsA level constant with 1-MCP treatment.
Abstract: The effects of 1-methylcyclopropene (1-MCP) on ascorbate (AsA) metabolism in two cultivars of broccoli (Brassica oleracea L. var. italica), ‘Haitsu’ and ‘Ryokurei’, were studied and the possible molecular mechanisms are discussed. The results showed that 1-MCP treatment delayed the yellowing and suppressed ethylene production. Meanwhile, the AsA content declined to a lower level in the control during storage, and the reduction of AsA was significantly suppressed by the treatment with 1-MCP in the two cultivars. Gene expression analyses by real-time PCR showed that 1-MCP treatment down-regulated the expression of BO-APX1 and BO-APX2, and up-regulated that of BO-DHAR and BO-GLDH compared with the control. The regulation of this gene expression might contribute to the suppression of AsA reduction by the 1-MCP treatment in ‘Haitsu’ and ‘Ryokurei’ broccoli. The results arising from this study might provide new insights into the possible mechanism, by which treatment with 1-MCP delayed senescence.
Abstract: The effects of 1-methylcyclopropene (1-MCP), an ethylene action inhibitor, on the senescence of broccoli (Brassica oleracea, L. var. italica) after harvest were studied, and its possible molecular mechanism was discussed. The results showed that 1-MCP treatment delayed the yellowing of broccoli florets, inhibited the activities of 1-aminocyclopropane-1-carboxylate acid (ACC) oxidase (ACO), and delayed the peaks in the ACC synthase (ACS) activity and ACC concentration. In addition, exogenous ethylene treatment did not accelerate yellowing in the florets pretreated with 1-MCP. The gene expression pattern of enzymes involved in ethylene biosynthesis and ethylene receptors in broccoli florets after harvest was investigated. 1-MCP treatment significantly decreased the expression of BO-ACS1, BO-ACS2, BO-ACO1, BO-ERS, BO-ETR1 and BO-ETR2. 1-MCP delayed the senescing process of broccoli by inhibiting the activities of enzymes involved in ethylene biosynthesis and gene expression of these enzymes and of ethylene receptors at the transcript level.
