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ABA signalling manipulation suppresses senescence of a leafy vegetable stored at room temperature

Miret, Javier A., Munné‐Bosch, Sergi, Dijkwel, Paul P.
Plant biotechnology journal 2018 v.16 no.2 pp. 530-544
1-aminocyclopropane-1-carboxylic acid, Brassica oleracea var. capitata, abiotic stress, abscisic acid, agonists, ambient temperature, biotic stress, cabbage, chloroplasts, cytokinins, defense mechanisms, ethylene, functional foods, glucosinolates, homeostasis, leaf blade, longevity, metabolism, nutritive value, phenylpropanoids, proteasome endopeptidase complex, shelf life, storage temperature, transcription (genetics), transcriptomics
Postharvest senescence and associated stresses limit the shelf life and nutritional value of vegetables. Improved understanding of these processes creates options for better management. After harvest, controlled exposure to abiotic stresses and/or exogenous phytohormones can enhance nutraceutical, organoleptic and commercial longevity traits. With leaf senescence, abscisic acid (ABA) contents progressively rise, but the actual biological functions of this hormone through senescence still need to be clarified. Postharvest senescence of detached green cabbage leaves (Brassica oleracea var. capitata) was characterized under cold (4 °C) and room temperature (25 °C) storage conditions. Hormonal profiling of regions of the leaf blade (apical, medial, basal) revealed a decrease in cytokinins contents during the first days under both conditions, while ABA only increased at 25 °C. Treatments with ABA and a partial agonist of ABA (pyrabactin) for 8 days did not lead to significant effects on water and pigment contents, but increased cell integrity and altered 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and cytokinins contents. Transcriptome analysis showed transcriptional regulation of ABA, cytokinin and ethylene metabolism and signalling; proteasome components; senescence regulation; protection of chloroplast functionality and cell homeostasis; and suppression of defence responses (including glucosinolates and phenylpropanoids metabolism). It is concluded that increasing the concentration of ABA (or its partial agonist pyrabactin) from the start of postharvest suppresses senescence of stored leaves, changes the transcriptional regulation of glucosinolates metabolism and down‐regulates biotic stress defence mechanisms. These results suggest a potential for manipulating ABA signalling for improving postharvest quality of leafy vegetables stored at ambient temperature.