Genome-wide identification of key genes responding to salt stress in Populus alba

Abstract Background The molecular mechanism of forest trees responding to salt stress remains poorly understood. As a fast-growing and widely adapted tree species,Populus albais planted in the world. Understanding the molecular mechanism ofP. albaresponding to salt stress is helpful to improve the yield ofP. albaartificial forest in salinized land. Results This study investigated the phenotypic and physiological characteristics ofP. albaseedlings under 300 mM NaCl stress. After seven days of salt stress, the leaves ofP. albaturned yellow and fell off. Whether under normal growth conditions or salt stress, CAT activities in roots were significantly higher than that in leaves. The root viability ofP. albadecreased significantly within 2 h of salt treatment, but gradually increased after 2 h of salt treatment. Intercellular CO₂concentration of leaves ofP. albaincreased significantly after 72 h of salt treatment, while other photosynthetic parameters decreased significantly after 72 h of salt stress. Chlorophyllaand chlorophyllbin leaves ofP. albadecreased gradually after 9 h of salt stress. The ratio of Na⁺/K⁺in roots and leaves ofP. albagradually increased after 1 and 2 h of salt stress, respectively. ABA and cytokinin contents in roots and leaves ofP. albaunder salt stress were increased significantly. Time-series transcriptomes of roots, stems, leaves, and apical buds ofP. albaunder NaCl stress were analyzed. Based on gene expression, physiological and biochemical data inP. albaunder salt stress, we performed weighted gene co-expression network analysis. Thirty-two candidate key genes ofP. albaresponding to salt stress were identified. Twenty-four candidate key genes showed salt tolerance inSaccharomyces cerevisiae. Especially for the four genes (Poalb01G005590,Poalb16G007310,Poalb01G036340, andPoalb06G010440), each exhibited strong tolerance to different kinds of salt stress. Conclusion The results of this study provide a new insight into the molecular mechanism of trees responding to salt stress.