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Exogenous Ethylene (exogenous + ethylene)
Selected AbstractsExogenous ethylene stimulates the long-term expression of genes related to anthocyanin biosynthesis in grape berriesPHYSIOLOGIA PLANTARUM, Issue 2 2003Ashraf El-Kereamy The treatment of grape berries (Vitis vinifera L. cv. Cabernet Sauvignon) with the ethylene-releasing compound, 2-chloroethylphosphonic acid (2-CEPA), at veraison is a method known to enhance grape skin colour. We observed that it produced a 6-fold increase, up to 30 pmol g,1 FW, of the cluster internal ethylene compared to untreated controls within the 24 h following treatment. This ethylene upsurge was associated with increased levels of chalcone synthase (CHS) and flavanone 3-hydroxylase (F3H) transcripts, which persisted over the following 20 days. Transcript levels of leucoanthocyanidin dioxygenase (LDOX) and UDP glucose-flavonoid 3- O -glucosyl transferase (UFGT) were similarly enhanced by 2-CEPA, although to a lesser extent. The effect on UFGT was confirmed at the protein level by an immunoblot analysis. The transcript accumulation of dihydroflavonol 4-reductase (DFR) was unaffected by 2-CEPA treatment. Examination of the levels of CHS, F3H and UFGT mRNAs in berries during bunch exposure to ethylene, revealed elevated levels of each transcript within the first 6 h of treatment when compared to nonethylene-treated controls. HPLC analyses of berry skin extracts showed that levels of each of the anthocyanins analysed (delphinidin, cyanidin, petunidin, peonidin and malvidin) increased over the 10 days following the ethylene burst, and decreased thereafter. However, anthocyanin levels at harvest were still higher in ethylene treated grapes than in controls. This data is the first evidence that ethylene triggers gene expression related to anthocyanin synthesis in grapes, and in addition, our results also confirm the existence of other regulatory modes in the anthocyanin biosynthetic pathway. [source] 1-Methylcyclopropene Counteracts Ethylene-Induced Microbial Growth on Fresh-Cut WatermelonJOURNAL OF FOOD SCIENCE, Issue 6 2006Bin Zhou ABSTRACT:, The effects of exogenous ethylene, 1-methylcyclopropene (1-MCP), or both on microbial growth on watermelon fruit and watermelon slices were investigated. Freshly harvested seedless watermelons (Citrullus lanatus, cv. Sugar Heart) were treated with 0.5 or 1.0 ppm 1-MCP, 10 ppm ethylene, 1-MCP + ethylene, or left untreated as controls. Fruits were processed into wedge-shaped slices, packaged into rigid trays sealed with a polyethylene film with a 29.2 pmol s,1 m,2 Pa,1 oxygen transmission rate. The slices were evaluated after 0-, 6-, and 12-d storage at 5 °C. Ethylene treatment alone increased the populations of aerobic bacteria, lactic acid bacteria, and yeasts and molds on the packaged slices during storage compared to those on corresponding control slices and resulted in extensive juice leakage from the slices. The ethylene treatment also resulted in high aerobic bacterial counts throughout the flesh of whole melons compared to the controls. Treating watermelons with 0.5 or 1.0 ppm 1-MCP prior to ethylene exposure counteracted the deleterious effects of ethylene. Extending the time from harvest to 1-MCP treatment increased the population of aerobic bacteria, but had no detectable effect on the growth of lactic acid bacteria or yeasts and molds. The results indicate that low concentrations (0.5 or 1.0 ppm) of 1-MCP can be used on whole watermelon to avoid deleterious effects of exogenous ethylene to which the melons could be exposed during shipping or storage. [source] An Overview of the Biology of Reaction Wood FormationJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2007Sheng Du Abstract Reaction wood possesses altered properties and performs the function of regulating a tree's form, but it is a serious defect in wood utility. Trees usually develop reaction wood in response to a gravistimulus. Reaction wood in gymnosperms is referred to as compression wood and develops on the lower side of leaning stems or branches. In arboreal, dicotyledonous angiosperms, however, it is called tension wood and is formed on the upper side of the leaning. Exploring the biology of reaction wood formation is of great value for the understanding of the wood differentiation mechanisms, cambial activity, gravitropism, and the systematics and evolution of plants. After giving an outline of the variety of wood and properties of reaction wood, this review lays emphasis on various stimuli for reaction wood induction and the extensive studies carried out so far on the roles of plant hormones in reaction wood formation. Inconsistent results have been reported for the effects of plant hormones. Both auxin and ethylene regulate the formation of compression wood in gymnosperms. However, the role of ethylene may be indirect as exogenous ethylene cannot induce compression wood formation. Tension wood formation is mainly regulated by auxin and gibberellin. Interactions among hormones and other substances may play important parts in the regulation of reaction wood formation. [source] Activation of a diverse set of genes during the tobacco resistance response to TMV is independent of salicylic acid; induction of a subset is also ethylene independentTHE PLANT JOURNAL, Issue 5 2000Ailan Guo Summary Through differential screening of a cDNA library, we cloned six groups of genes that are expressed relatively early in the inoculated leaves of tobacco resisting infection by tobacco mosaic virus (TMV). Induction of all these genes was subsequently detected in the uninoculated leaves; thus, their expression is associated with the development of both local and systemic acquired resistance. Exogenously applied salicylic acid (SA) was observed to induce these genes transiently. However, analyses with transgenic NahG plants, which are unable to accumulate SA, demonstrated that expression of these genes in TMV-inoculated leaves is mediated via an SA-independent pathway. Because the expression kinetics of these genes differ from those associated with the well-characterized pathogenesis-related protein (PR-1) and phenylalanine ammonia-lyase (PAL) genes, we propose that they belong to a group which we designate SIS, for SA-independent, systemically induced genes. Interestingly, the expression of several SIS genes in the uninoculated leaves of TMV-infected NahG plants was delayed and/or reduced, raising the possibility that SA is involved in activating some of these genes in systemic tissue. Most of the SIS genes were induced by exogenous ethylene. However, analyses of infected NahG plants treated with ethylene action and/or synthesis inhibitors indicated that the TMV-induced expression of several SIS genes is independent of ethylene as well as SA. [source] | ||||||||||