Effects Of Drought Stress On Physiological And Biochemical Characteristics And Histone Acetylation In Wheat

Wheat is one of the most important food crops in China, and drought is a limiting factor for the yield of Wheat. In this study, Bainong207 and Luohan2 were chosen as experimental materials and 20% PEG-6000 were employed to simulate drought condition. The changes of physiological and biochemical characteristics, H3K9 ac content and expression level of histone acetylation modified enzymes with Bainong207 and Luohan2 under 20% PEG-6000 treatment were examined. The main results are as follows:(1)Differences of phenotypes and physiological and biochemical indexes between Bainong207 and Luohan2 under drought stress.In order to compare the ability of drought resistance, the root growth rate, root fresh weight, root dry weight, fresh weight on the ground, dry weight on the ground, leaf water content and leaf relative conductivity of medium penetration with Bainong207 and Luohan2 under drought stress were determined. Results showed that the ability of drought-resistant of Luohan2 is better than that of Bainong207.(2)Under drought stress, the differences of expression patterns of drought response genes between Bainong207 and Luohan2.The molecular mechanisms of response to drought stress in crops include ABA dependent pathway and non ABA dependent pathway. DREB2 is a key factor in drought stress response. Cor(cold-responsive) / Lea(late embryogenesis-abundant) is an important genes in the downstream of DREB2. The expression of drought resistance related genes DREB2, Wdhn13 and Wrab17 under drought stress were analyzed by real-time Quantitative PCR. The results showed that the expression levels of the three drought resistant genes were increased rapidly in the two wheat cultivars after two hours. However, with the extention of drought stress time, three gene expression levels of the Bainong207 continued to decline, while that of Luohan2 rised.(3) Changes of genome wide of H3K9 ac content modification between Bainong207 and Luohan2 under drought stress.Immunostaining assay and Western blot were carried to compare the change of genome wide H3K9 ac content between the two wheat coltivars. The results were as follows: the H3K9 ac content of Bainong207 declined, while that of Luohan2 increased after 24 hours of drought stress.(4) Differences of expression levels of histone acetylation modified enzymes between Bainong207 and Luohan2 under drought stress.Histone acetylation is regulated by histone acetyltransferase(HAT) and histone deacetylase(HDAC) enzymes. In order to reveal the difference of histone acetylation in the two wheat cultivars with different levels of drought resistance, the expression of HAT1, HAT2, HDAC2 and HDAC4 were analyzed by real-time Quantitative PCR. The results showed that the expression levels of HAT1 and HAT2 genes of Bainong207 were increased under drought stress, while those of HDAC2 and HDAC4 were declined. With the extention of drought stress, the expression levels of the HAT1, HAT2, HDAC2 and HDAC4 were returned to normal level. After rewatering 48 hours, the expression levels of the histone acetyltransferase genes returned to normal level, but the histone deacetylase was still retained higher level. With the increase of drought stress time, the expression levels of the HAT1 and HAT2 genes were continued to increase in Luohan2, but the expression levels of HDAC2 and HDAC4 were declined. After rewatering 48 hours, the expression levels of the histone acetyltransferase and histone deacetylase genes were returned to normal level.