拟南芥高迁移率族蛋白B(AtHMGB)族基因启动子的转录激活功能

Activation of the Promoter of Arabidopsis High Mobility Group Protein B Family Genes(AtHMGB)

为了解高迁移率族蛋白B族(high mobility group protein B,HMGB)基因调控植物响应低温、高盐和干旱等外源胁迫的表达调控方式,本文克隆了拟南芥AtHMGB前5个家族成员的启动子区域(PAtHMGB1,PAtHMGB2,PAtHMGB3,PAtHMGB4和PAtHMGB5).运用基因重组技术将其分别替换表达载体上35S启动子区域获得重组表达载体,利用农杆菌介导法侵染烟草获得稳定表达的转基因烟草.运用实时定量PCR检测上述5种启动子的转基因烟草,观察在外源胁迫(低温、高盐和干旱)处理前后gusA基因的表达差异,同时检测转基因烟草种子在不同外源胁迫条件下的萌发状况.检测结果证实,在低温胁迫下,PAtHMGB2,PAtHMGB3和PAtHMGB4正调控gusA基因的表达,而在干旱或盐胁迫下,gusA基因的表达被PAtHMGB2和PAtHMGB3负调控.种子萌发结果表明,在干旱胁迫下,PAtHMGB2调控下的转基因烟草比野生型烟草萌发及生长迟缓;在低温胁迫下,PAtHMGB2调控的转基因烟草长势明显强于野生型.本研究克隆了拟南芥AtHMGB家族前5个成员启动子,分析其生物学功能发现,PAtHMGB2在响应低温和干旱胁迫方面效果尤为显著.

To understand the functions of high mobility group protein B（HMGB） in the responses to environmental stimuli of plants,we cloned the promoter regions of 5 AtHMGB genes in Arabidopsis（PAtHMGB1,PAtHMGB2,PAtHMGB3,PAtHMGB4 and PAtHMGB5）,and replaced the 35S promoters in pBI121 vectors.The obtained plasmids were introduced into tobacco by Agrobacterium tumefaciens.Real-time PCR was used to detect the gusA expression under various abiotic stresses in transformed tobaccos,and the germination and growth of tobacco seeds were examined.The expression of gusA promoted by PAtHMGB2,PAtHMGB3 and PAtHMGB4 were up-regulated under the cold stress,and down-regulated by PAtHMGB2 and PAtHMGB3 under drought stress.Retarded germination and subsequent growth was observed in PAtHMGB2 transformed tobacco compared with wild-type under drought stress,whereas under cold stress conditions for plants with PAtHMGB2.Taken together,we cloned the promoters of 5 AtHMGB genes of Arabidopsis,including PAtHMGB2 that functioned under both cold and drought stress.