Abstract: Bothriochloa ischaemum is an excellent native grass species with drought tolerance. In order to explore the structure and function of the transcription factor MYB of Bothriochloa ischaemum,a R2R3-MYB gene,BiMYB52 encoding 237 amino acids,was cloned from Bothriochloa ischaemum by topoisomerase rapid cloning method based on a segment of MYB sequence with significant changes in expression in response to drought stress. To further study the drought resistance of BiMYB52,the BiMYB52 promoter sequence was amplified by genome walking technique,and the pCAMBIA1301-BiMYB52 expression vector was constructed.A wild Arabidopsis thaliana was transformed by Agrobacterium mediated inflorescence infection to form a transgenic Arabidopsis,then drought stress was applied to the transgenic plants. The results showed that the survival rate of the transgenic Arabidopsis was significantly higher t，the MDA content significantly lower,and the content of proline was significantly higher than those of the control,non-transgenic Arabidopsis. It is speculated that BiMYB52 may increase the resistance of Arabidopsis to drought stress. This provides a candidate gene and theoretical basis for drought resistance breeding of Bothriochloa ischaemum.

Key words: Bothriochloa ischaemum, MYB transcription factor, Drought stress, Expression analysis, Transgenic

摘要： 白羊草(Bothriochloa ischaemum)是一种耐旱的优良乡土草种。为了探索白羊草转录因子MYB的结构和功能，本研究以白羊草转录组测序中筛选出的一段对干旱胁迫响应表达量变化显著的MYB序列为基础，采用基于拓扑异构酶快速克隆法从白羊草中克隆了一个R2R3-MYB基因BiMYB52，该基因编码237个氨基酸。为了深入研究BiMYB52基因的抗旱性，利用染色体步移技术扩增出了BiMYB52启动子序列，构建了pCAMBIA1301-BiMYB52过表达载体，采用农杆菌介导的花序侵染法对拟南芥(Arabidopsis thaliana)进行遗传转化，然后对野生拟南芥和转基因拟南芥进行干旱胁迫处理。结果表明，干旱胁迫复水后，转基因拟南芥的存活率显著高于野生拟南芥，丙二醛(Malondialdehyde,MDA)含量是干旱胁迫后转基因拟南芥的显著低于对照，脯氨酸(Proline,Pro)含量则显著高于对照。由此推测BiMYB52基因可能增加了拟南芥对干旱胁迫的抵抗能力。这为白羊草抗旱育种提供候选基因和理论基础。

关键词: 白羊草, MYB转录因子, 干旱胁迫, 表达分析, 转基因