Endogenous signals in response to exogenous factors determine the senescence of flowers. Interactions among phytohormones especially abscisic acid (ABA) and ethylene are the major determinant of the senescence. In the present study, complex expression patterns of the genes related to ABA and ethylene as endogenous signals were investigated on cut carnations (Dianthus caryophyllus L.) that were exposed to different light spectra. Expression of ethylene biosynthetic (DcACS and DcACO), and signaling (DcETR and DcEin2) genes and also genes involved in ABA biosynthesis (DcZEP1 and DcNCED1), transport (DcABCG25 and DcABCG40) and catabolism (DcCYP707A1) were evaluated in petals of carnations exposed to three light spectra [white, blue and red]. Lowest relative membrane permeability (RMP) was detected in flowers that exposed to Blue light (BLFs), as a consequence, the longest vase life was found in BLFs. The Red and White lights markedly accelerated flower senescence and increased expression of DcACS and DcACO on day 6 and 10 of vase life assessment respectively; while Blue light inhibited the expression of ethylene biosynthetic genes. Expression of the genes involved in the production and transport of ABA and in signal transduction of ethylene was elevated during vase life of flowers irrespective of exposure to different light spectra. In conclusion, Blue light can be an effective environmental factor to extend the vase life of carnation flowers by delaying the petal senescence through down-regulation of ethylene biosynthetic genes and up-regulation of ABA biosynthetic genes.
Keywords: Abscisic acid; Carnation; Ethylene; Light spectrum; Senescence.
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