جستجوی مقالات مرتبط با کلیدواژه « تحمل به خشکی » در نشریات گروه « زیست شناسی »

In order to investigate the activity of antioxidant enzymes of 14 tea clones under normal and drought stress conditions, two separate experiments were carried out in a randomized complete block design with two replications in 2017 at Fashalem Tea Research Station in Rasht. Irrigation in both designs was carried out routinely until July 22 followed by a drought stress treatment for one plot until August 22 when tea leaves were harvested. Tea leaves from each plot of the both experiments were then removed and transferred to a freezer at -80 °C. The activity of the antioxidant such as ascorbate peroxidase, superoxide dismutase, catalase, peroxidase, phenylalanine ammoniaase, lipid peroxidase, malondialdehyde, β-carotene, and lycopene were measured. The results showed that drought stress increased the activity of antioxidant enzymes. Based on the results obtained from the mean comparisons, clones 100, 399 and Bazri, had the highest activity for ascorbate peroxidase, superoxide dismutase, catalase, peroxidase, phenylalanine ammoniaase, and lipid peroxidase under drought stress conditions. On the other hand, these clones had the lowest contents of malondialdehyde. Clones 278 and 276 on the other hand, had the least values of antioxidant enzymes under drought stress conditions (except malondialdehyde) and were considered as sensitive clones.

Dehydrins are known as late-embryogenesis abundant (LEA) proteins Group II, which are accumulated during low-temperature or water-deficit conditions. They are asumed to play a role in freezing and drought-tolerance in plants. In order to study the impact of dehydrins in response of tolerant and sensitive genotypes to drought, one experiment was carried out in a factorial design based on CRD for a wild ecotype and two barley cultivars in greenhouse. The barley cultivars including Yusef (HV1) and Morocco (HV2) and wild ecotype (HS) were as the first factor and irrigation treatment with three levels consisted of normal (70% of water holding capacity of soil), mild stress (30%) and severe stress (10%) was as the second factor. Normal irrigation was continued in two leaf stage and then discontinued for plants under stress to achieve certain level of stress. The samples were collected from the expanded leaves in vegetative stage for physiological and molecular analysis. Analysis of variance for physiological characteristics showed that the effect of water stress on all traits and differences between genotypes were significant, and HV2 had significantly lower dry mater production and relative water content than the other genotypes. Based on the real time PCR results, among 13 barley dehydrin genes, except for Dhn8 and Dhn13, expression of other genes significantly upregulated under severe drought condition. The expression level of Dhn3, Dhn7, Dhn9 and Dhn10 was increased in the tolerant genotypes, HV1 and HS, whereas the expression level of Dhn1 and the other genes increased only in Yusof and HS, respectively that was indicative of the role of dehydrin genes in drought tolerance. The increase of Dhn12 expression level in wild ecotype through drought condition is reported for the first time in the current study.