烟草转录因子NtMYB4a响应干旱、低温和茉莉酸甲酯胁迫的功能分析

Function Analysis of Tobacco Transcription Factor NtMYB4a in Response to Drought,Low Temperature and Methyl Jasmonate Stress

MYB转录因子是植物体内最大的一类转录因子,在植物应对非生物胁迫中发挥重要作用。为探讨烟草NtMYB4a基因在响应干旱、低温和茉莉酸甲酯胁迫下的功能,以NtMYB4a基因的过表达和敲除突变体及野生型烟株为材料,采用RT-qPCR技术分析了干旱、低温和茉莉酸甲酯处理0、1、3、6、12、24和48 h后烟草叶片中NtMYB4a的表达变化以及脯氨酸和丙二醛含量差异。结果显示:过表达突变体中NtMYB4a的表达量极显著高于野生型烟株,且不易受干旱、低温和茉莉酸甲酯胁迫的影响,烟叶中的脯氨酸含量增高,丙二醛含量降低;而基因敲除突变体中NtMYB4a的表达量显著低于野生型烟株,且易受干旱、低温和茉莉酸甲酯胁迫的影响,烟叶中的脯氨酸含量降低,丙二醛含量增加。此外,利用Plant CARE软件分析了NtMYB4a启动子区域,结果显示该区域含有赤霉素、生长素、脱落酸、茉莉酸甲酯、光、干旱、低温等激素和非生物胁迫相关的顺式作用元件。这些结果表明,NtMYB4a基因的表达受干旱、低温胁迫和茉莉酸甲酯的诱导,可能与烟株的抗逆性相关。

MYB transcription factors are the largest type of transcription factors in plants and play an important role in the response of plants to abiotic stress.In order to explore the function of tobacco NtMYB4a gene under drought,low temperature and Methyl jasmonate(MeJA)stress,the overexpression and knockout mutants of NtMYB4a gene and wild-type tobacco plants were used to analyze the changes of NtMYB4a expression and the differences of proline and malondialdehyde content in tobacco leaves treated with drought,low temperature and MeJA for 0,1,3,6,12,24 and 48 h by RT-qPCR technology.The results showed that the expression of NtMYB4a in the overexpression mutants was significantly higher than that in the wild-type tobacco plants,and it was not easy to be affected by drought,low temperature and MeJA stress.The proline content in the tobacco leaves increased,and the malondialdehyde content decreased.However,the expression of NtMYB4a in gene knockout mutants was significantly lower than that in wild-type tobacco plants,and it was susceptible to drought,low temperature and MeJA stress.The content of proline in tobacco leaves decreased,and the content of malondialdehyde increased.In addition,the NtMYB4a promoter was analyzed by Plant CARE software,and the results showed that the region contains cis-acting elements related to abiotic stresses such as gibberellin,auxin,abscisic acid,MeJA,light,drought,and low temperature.These results indicated that the expression of NtMYB4a gene is induced by drought,low temperature and MeJA stress,which may be related to the stress resistance of tobacco plants.