Acetylation and deacetylation of histones are important for regulating a series of biological processes in plants. Histone deacetylases (HDACs) control the histone deacetylation that plays an important role in plant response to abiotic stress. In our study, we show the evidence that GhHDT4D (a member of the HD2 subfamily of HDACs) is involved in cotton (Gossypium hirsutum) response to drought stress. Overexpression of GhHDT4D in Arabidopsis increased plant tolerance to drought, whereas silencing GhHDT4D in cotton resulted in plant sensitivity to drought. Simultaneously, the H3K9 acetylation level was altered in the GhHDT4D silenced cotton, compared with the controls. Further study revealed that GhHDT4D suppressed the transcription of GhWRKY33, which plays a negative role in cotton defense to drought, by reducing its H3K9 acetylation level. The expressions of the stress-related genes, such as GhDREB2A, GhDREB2C, GhSOS2, GhRD20-1, GhRD20-2 and GhRD29A, were significantly decreased in the GhHDT4D silenced cotton, but increased in the GhWRKY33 silenced cotton. Given these data together, our findings suggested that GhHDT4D may enhance drought tolerance by suppressing the expression of GhWRKY33, thereby activating the downstream drought response genes in cotton.

组蛋白的乙酰化和脱乙酰化对于调节植物中的一系列生物过程很重要。组蛋白脱乙酰基酶（HDAC）控制组蛋白脱乙酰基化，该组蛋白脱乙酰基化在植物对非生物胁迫的响应中起着重要作用。在我们的研究中，我们表明，GhHDT4D（HDAC的HD2亚家族的成员）参与棉花（证据陆地棉）干旱胁迫。拟南芥中GhHDT4D的过表达提高了植物对干旱的耐受性，而棉花中GhHDT4D的沉默导致植物对干旱的敏感性。同时，GhHDT4D中的H3K9乙酰化水平发生了变化与对照组相比，静音棉。进一步的研究表明，GhHDT4D通过降低其H3K9乙酰化水平，抑制了GhWRKY33的转录，而GhWRKY33在棉花的抗旱性中具有负作用。在GhHDT4D沉默棉中，与胁迫相关的基因GhDREB2A，GhDREB2C，GhSOS2，GhRD20-1，GhRD20-2和GhRD29A的表达显着降低，而在GhWRKY33沉默棉中则升高。综合这些数据，我们的研究结果表明，GhHDT4D可能通过抑制GhWRKY33的表达来增强抗旱性。从而激活棉花下游的干旱反应基因。