【摘要】 【目的】研究外源2,4-表油菜素内酯(2,4-epibrassinolide, EBR)对干旱胁迫条件下西瓜幼苗生长以及相关基因表达的影响，为西瓜抗旱研究提供理论基础。【方法】以西瓜品种齐红1号为材料，利用15%聚乙二醇(PEG6000)模拟干旱胁迫，设置3个处理CK(清水)、PEG和PEG+EBR,其中EBR的浓度为0.01 mg/L。检测不同处理后西瓜幼苗的生物量、光合作用指标、叶绿素含量、抗氧化酶活性以及相关基因的表达量。【结果】喷施外源EBR可以缓解干旱胁迫对西瓜幼苗生长发育的抑制和损害程度，还可以通过增加应答基因的表达量，激活EBR信号转导途径，提高西瓜幼苗的耐旱性。喷施外源EBR西瓜幼苗株高、根长、地上鲜重、地下鲜重较PEG胁迫分别增加了2.41%、36.76%、1.88%和3.42%;而且也增强光合作用各项指标，抗氧化酶(POD和SOD)活性。油菜素内酯(BRs)信号转导途径关键应答基因BRI1、BIN2、BES1和DWF4的表达量也呈现不同程度变化，抗旱相关基因CDSP32和MYB101的表达量也有显著变化。【结论】外源EBR能够有效缓解干旱胁迫对西瓜幼苗造成的损害，从而提高西瓜幼苗的抗旱性。更多还原

【Abstract】 【Objective】 To reveal the effects of exogenous 2,4-epibrassinolide(EBR) on the growth and related gene expression of watermelon seedlings under drought stress, so as to provide a theoretical basis for the study of watermelon drought resistance.【Methods】 Watermelon variety Qihong 1 was taken as the experimental material by using 15% polyethylene glycol(PEG6000) to simulate drought stress, and then, three treatments were set up: CK(clear water),PEG and PEG + EBR,in which the concentration of EBR was 0.01 mg/L.Finally, the biomass, photosynthesis index, chlorophyll content, antioxidant enzyme activity and expression of related genes of watermelon seedlings after different treatments were detected.【Results】 Spraying exogenous EBR could alleviate the inhibition and damage of drought stress on the growth and development of watermelon seedlings and also activate EBR signal transduction pathway and improve the drought tolerance of watermelon seedlings by increasing the expression of response genes.Compared with PEG stress, the plant height, root length, aboveground fresh weight and underground fresh weight of watermelon seedlings sprayed with exogenous EBR increased by 2.41%,36.76%,1.88% and 3.42% respectively.Moreover, it also enhances various indicators of photosynthesis and the activities of antioxidant enzymes(POD and SOD).The expression of key response genes BRI1,BIN2,BES1 and DWF4 of Brassinolide(BRS) signal transduction pathway also changed to varying degrees, and the expression of drought related genes CDSP32 and MYB101 also changed significantly.【Conclusion】 Exogenous EBR can effectively alleviate the damage caused by drought stress to watermelon seedlings, thus improving the drought resistance of watermelon seedlings.更多还原