基于转录组的杉木BES1转录因子家族鉴定和响应干旱表达

Transcriptome-Based Identification and Expression of the Chinese Fir BES1 Transcription Factor Family under Drought

杉木作为中国南方重要的速生商品材树种,分布区广,环境变化差异大,其生长发育受到干旱等多种非生物胁迫的影响。BES1转录因子家族是BR(Brassino steroids)信号的关键响应元件,在BR调控的植物根、茎、叶等器官发育和抗逆能力方面扮演重要角色。本研究在高通量转录组测序获得的数据基础上,结合生物信息学的方法,对杉木BES1转录因子家族的保守结构域、系统发育、理化性质以及在干旱胁迫下的表达进行了分析,为解析杉木BES1基因的功能奠定基础。通过注释和筛选,确定了10个杉木BES1转录因子家族成员,平均编码355个氨基酸,等电点(pI)5.92~9.97,不稳定系数均超过40,对水有较强的亲和性,且亚细胞定位都在细胞核。这10个BES1家族蛋白均含有BES1_N和Glyco_hydro_14结构域,而且系统发育显示和拟南芥一样分为3个亚族,进化较为保守。转录表达谱显示ClBAM7-1和ClBEH1等6个基因在干旱胁迫的根部表达下调,而其中相反的是ClBZR1和ClBAM8-2在干旱胁迫的叶片中却表达上调,说明它们两个在叶片参与对干旱的正向相应,而ClBAM7-2在根部被干旱诱导,表达上调。这表明杉木BES1基因家族的各个成员在不同处理的不同器官中呈现差异表达。本研究在转录水平上对杉木BES1转录因子家族进行了鉴定和表达分析,为后续功能验证和耐旱型优良杉木无性系选育提供基础。

Chinese fir(Cunninghamia lanceolata)is an important fast-growing commercial timber tree species in southern China.Its growth and development are affected by a variety of abiotic stresses such as drought,because of the wide variation in environmental conditions across its range.The BES1 transcription factor family is a key response element for BR(Brassino steroids)signaling and plays an important role in the root,stem,leaf and other organ development and stress tolerance of plants regulated by BR.On the basis of the data obtained from highthroughput transcriptome sequencing,we analyzed the conserved domains,phylogeny,physicochemical properties,and expression of the Chinese fir BES1 transcription factor family under drought stress.These data are the fundamental to investigate the function of the BES1 gene.Ten BES1 genes were identified in Ch inese fir by screening and annotation.They encode an average of 355 amino acids with an isoelectric point(pI)of 5.92 to 9.97.They are all subcellularly localized in the nucleus and have a strong affinity for water,because their instability coefficients are above 40.The 10 Chinese fir BES1 family proteins all contain BES1_N and Glyco_hydro_14 domains,and the phylogeny shows a more conservative evolutionary division into three subfamilies,as in Arabidopsis.Transcriptional expression profiles showed that six genes,including ClBAM7-1 and ClBEH1,were down-regulated in drought-stressed roots,whereas the opposite of these,ClBZR1 and ClBAM8-2,were upregulated in drought-stressed leaves,suggesting that both of them are involved in a positive correspondence to drought in leaves.ClBAM7-2 was induced by drought in roots and its expression was up-regulated.This indicates that the individual members of the Chinese fir BES1 gene family show differential expression in different organs of different treatments.In this study,the Chinese fir BES1 transcription factor family was identified and expressed at the transcription level,laying the foundation for subsequent functional verification and breeding of excellent drought-tolerant Chinese fir clones.