Study on Genetic Diversity of some Barley (Hordeum vulgare L.) Cultivars using SSR Marker and Physiological Traits Plant Pigments and Proline undar Late Cold Stress

Plants are often exposed to a wide range of abiotic stresses, which have adverse effects on the survival, growth, quality, and quantity of crops. Coldness is one of these stresses that the late spring cold can cause great damages to the crop (cereal) planting during the reproductive period. The purpose of this research was to investigate the effect of spring cold on the physiological traits, associated with stress toleration including proline amino acid, and pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid) in the reproductive stage.To this end, an experiment was conducted in a controlled condition (greenhouse) with a combined analysis model based on a completely randomized design in four media (control temperature level of +8°C, +2°C, 0°C, and -2°C)for 20 cultivars of barley and three replicationin the Faculty of Agriculture of Tarbiat Modarres University, Iran, in 2016-17. The results of the analysis of variance showed that cold stress levels, cultivar, and interaction of cultivar on cold were significant for all the traits at 1% probability level.Cold-tolerant cultivars had higher levels of proline (Jolgeh cultivar) and plant pigments (Yousef and Nik) at different levels of cold stress. The cluster analysis was performed through the Ward method using the Euclidean distance coefficient to determine the genetic relationships between the studied cultivars, and the studied cultivars were divided into five groups at the control and severe stress (-2°C) levels and tolerated cultivars were grouped together. 12 pairs of microsatellite primers were used to study the genetic diversity in the molecular segment and the average polymorphism content information was estimated as much as 0.38. The cultivars were grouped through the Dice similarity coefficient as well as cluster analysis via the UPGMA model, and 20 cultivars of barley were divided into 4 groups. The results of correlation analysis through stepwise regression analysis showed a high correlation (highest coefficient of explanation) for Bmag0337 indicator with proline (R2=0.43), Bmac0518 indicator with chlorophyll a and total chlorophyll (R2=0.29), EBmac0602 indicator with chlorophyll b (R2=0.15), and Bmag0375 (R2=0.44) with carotenoid trait.