Exogenous EBL (24-Epibrassinolide) Alleviate Cold Damage in Strawberry

Low temperature constitutes one of the major threats in horticulture and is adversely affecting fruit production worldwide. Plant hormones, including 24-Epibrassinolide (EBL), may mitigate the malignant effects of cold stress on plants. We investigated the influences of EBL application on protein and proline content, lipid peroxidation and organic and phenolic acids of strawberry plant under cold stress. Two days before the chilling stress, three different EBL doses (1, 2 and 4 mM) were treated once (in August) to plant rhizoplane (above plant parts of soil) as solution except control. To perform chilling treatment, the plants were transferred to a cold storage from the greenhouse. Storage temperature decreased from 15 degrees C to 7 degrees C step by step and plants were hold 24 h at 7 degrees C. End of the study, 4 mM EBL decreased protein content in leaf and root, while it increased in stem. Among tissues of strawberry plant, higher accumulation of malondialdehyde (MDA) was observed in leaves, therefore it can be accepted that leaves are more vulnerable than stems and roots. Different EBL doses enhanced phenolic acids compared to control. The predominant phenolic acid was chlorogenic acid. EBL application increased organic acids except oxalic and malic acids compared to control. The main organic acid found in strawberry leaves exposed to cold stress in the current experiment was malic acid followed by citric and tartaric acids. Our results demonstrated that EBL alleviated the deleterious effects of cold stress in strawberry plant may be due to organic and phenolic acids and maintaining cell membrane integrity.