Epigenetic evaluation of melatonin application in drought and salt stress conditions in bean (Phaseolus vulgaris L.) genotypes

Common beans are an important type of legume used in human nutrition to obtain high protein, low fat, high levels of vitamins and minerals. Plants are exposed to various biotic and abiotic stresses throughout their lives, and they have developed various mechanisms to withstand against stresses. The purpose of this study was to ascertain the impact of exogenous melatonin application to bean genotypes on biochemical and epigenetic alterations in root and leaf tissues under salt and drought stress conditions. The seeds germinated for seven days were then grown in containers with Hoagland's solution until the 5-leaf stage and 0 and 200 μM melatonin was foliar sprayed to these plants. After 24 hours, they were placed in Hoagland's solution containing different doses of salt (0 and 150 mM) and PEG6000 (0 and 20%). Biochemical MDA and H2O2, antioxidant enzyme activity (SOD, POD and CAT) and DNA methylation changes (CRED-iPBS) were determined. The investigation revealed that the stresses provided to both genotypes increased the levels of MDA and H2O2, but the application of melatonin during salt stress decreased these parameters. SOD, POD and CAT antioxidant activities of the genotypes varied according to the treatments. Furthermore, according to DNA methylation results, both stress conditions and melatonin treatment caused changes in DNA methylation. Determination of this effect of melatonin under salt and drought stress conditions in bean at genomic and transcriptomic levels will support the findings of this study.