Mehdi Nazari; Mohammad Sayyari
Abstract
The present investigations focused on the role of calcium ascorbate (CaAsc) on tomato seedlings under low-temperature stress. Study was conducted by spraying aqueous solution of CaAsc at 0, 50, and 100 mM, on tomato seedlings with 5-7 true leaves in order to counteract the adverse impacts of chilling ...
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The present investigations focused on the role of calcium ascorbate (CaAsc) on tomato seedlings under low-temperature stress. Study was conducted by spraying aqueous solution of CaAsc at 0, 50, and 100 mM, on tomato seedlings with 5-7 true leaves in order to counteract the adverse impacts of chilling stress. One week after foliar application of CaAsc, all seedlings were exposed to a chilling temperature of 3±0.5 °C for six days (six hours per day) in a growth chamber. Loss of membrane integrity due to chilling stress led to oxidation of phenolic compounds by activation of peroxides (POD) and polyphenol oxidase (PPO) enzymes. Higher phenylalanine ammonia-lyase (PAL) activity, which is responsible for phenolic compounds accumulation, due to chilling temperature, has been considered as defense mechanism of chilling stress. The results revealed that application of 50 mM CaAsc ameliorated chilling injury of tomato seedling, which was associated with lower electrolyte leakage (16.2 %) and malondialdehyde (1.54 nmol g-1 FW) accumulation. Also, CaAsc-treated seedlings with 50 and 100 mM of CaAsc exhibited higher total phenols accumulation (36.2 and 28.4 mg pyrogallol g-1 FW, Respectively) which results from higher PAL enzyme activity concurrent with lower POD and PPO enzymes activity. Enhancing chilling tolerance in tomato seedling treated with 50 mM CaAsc by triggering phenols metabolism was associated with better seedling growth rate.
Ghader Habibi
Abstract
Salicylic acid (SA) plays an important role in the regulation of plant ripening and responses to abiotic stresses. In this study, the protective effect of SA on cold stress-caused oxidative damage in grape (Vitis vinifera L.) bunches was investigated during cold storage. Grape bunches treated with ...
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Salicylic acid (SA) plays an important role in the regulation of plant ripening and responses to abiotic stresses. In this study, the protective effect of SA on cold stress-caused oxidative damage in grape (Vitis vinifera L.) bunches was investigated during cold storage. Grape bunches treated with 2 mM SA and stored at 0°C with 85-90% RH for 30 days. Samples were selected from each treatment for physical and chemical analysis before storage, midpoint of storage, end of storage and end of shelf life. The results showed that the cold storage induced lipid peroxidation, decay incidence and loss of fresh weight, while SA pretreatment mitigated these effects in “Bidaneh Sefid” and “Qzl uzum” cultivars. In these cultivars, SA-induced protection against cold damage was accompanied by decrease in malondialdehyde (MDA) content, and caused an increase in catalase (CAT) and superoxide dismutase (SOD) activity. Additionally, SA-induced protection against cold injury was mediated through promoting total phenolics concentration and phenylalanine ammonia-lyase (PAL) activity. The present findings suggest that although variability in the protective effect of SA against cold damage was observed between grape cultivars, SA could alleviate the cold-induced oxidative stress in grape bunches during cold storage.
