Investigation of HD2 family histone deacetylases relationship in drought stress response and root growth in Arabidopsis thaliana
Abstract
Despite evidence that certain HD2 family histone deacetylases (HDACs) play an important role in plant growth and stress response, the coordination of HD2-type HDACs in these processes remains largely unknown. Arabidopsis contains four HD2s called HD2A, HD2B, HD2C, and HD2D. I found that HD2A and HD2C coordinate to positively regulate drought stress response. The hd2a.hd2c double mutant (Mac16) exhibits decreased survival and increased water loss under drought due to modified stomatal closure as compared to the single mutants hd2a and hd2c. Gene expression analysis showed that the expression of stomatal closure-related genes ABI1, ABI2, and SLAC1 was significantly affected in the Mac16 as compared to the hd2a and hd2c. Conversely, plants overexpressing HD2A or HD2C showed enhanced survival under drought stress and decreased water loss from leaves. Both HD2A and HD2C also play role in controlling root growth under stress. Furthermore, I demonstrated that HD2A and HD2C positively regulate root growth. Mac16 showed decreased root growth, compared to hd2a and hd2c. Importantly, the GA2ox1 and GA2ox2, which catabolise bioactive gibberellic acids, were significantly upregulated in the Mac16 as compared to the single mutants, thus caused decreased root growth in the Mac16. Moreover, increased genome-wide H3K9 acetylation was observed in the Mac16 as compared to the single mutants. Additionally, Y2H and BiFC analysis showed that both HD2s can physically interact with each other. Overall, my investigation revealed that HD2A and HD2C coordinate to play a cumulative role in drought stress response and root growth in Arabidopsis.