沙地云杉LBD基因家族鉴定及盐胁迫响应分析

Identification and Expression Patterns in Response to Salt Stress of the LBD Gene Family in Picea mongolica

沙地云杉(Picea mongolica)是我国稀有珍贵树种,具有耐旱、耐寒、耐沙埋的优良抗性。LBD(lateral organ boundaries domain)是植物侧生器官中重要的转录因子,在植物生长发育和胁迫应答进程中起关键作用,但目前尚未报道有关沙地云杉中LBD基因家族的研究。本研究参考挪威云杉全基因组数据及沙地云杉转录组数据鉴定沙地云杉LBD基因,进行生物信息学分析并利用qRT-PCR检测LBD基因在不同组织(茎尖、主根、侧根、茎和叶)及盐胁迫胁迫条件下的表达水平。结果表明,在沙地云杉转录组中共鉴定出30个LBD基因(PmLBD1-30),蛋白序列长度在119~309 aa之间,分子量为10.5~33.4 kD,等电点介于5.15~9.26之间,Cell-PLoc亚细胞定位显示均位于细胞核中;所有的LBD蛋白结构域、基因结构高度保守,并由相似的基序组成;根据系统发育树可将其分为5个亚家族(Class I a~e),沙地云杉在各类中的成员依次为4,11,5,1,9个;qRT-PCR试验结果显示,PmLBDs在不同组织中均有表达,如PmLBD2/5/18/19在茎中高表达,ClassⅠb中的PmLBD9/20/23基因在侧根中强烈表达;大多数PmLBDs的表达强烈响应盐胁迫,17个PmLBD基因在盐处理后上调表达,而6个PmLBD基因在盐处理后下调表达,且同一亚族基因表达情况呈现相似趋势。

Picea mongolica is a rare and precious tree species in China,with excellent resistance to drought,cold and sand burial.LBD(lateral organ boundaries domain)is an important transcription factor in plant lateral organs,which plays a key role in plant growth and development and stress response.However,LBD genes hadn􀆳t yet been reported in P.mongolica.In this study,the LBD genes were identified by the genome data of Picea abies and transcriptome data of P.mongolica and bioinformatics analysis were performed.The expression levels of the LBD genes in different tissues(shoot tip,main root,lateral root,stem and leaf)and under salt stress were detected by qRT-PCR.The results showed that a total of 30 LBD genes(PmLBD1-30)were identified in the transcriptome of P.mongolica.Their protein sequence length ranged from 119 to 309 aa,molecular weight ranged from 10.5 kD to 33.4 kD,and isoelectric point(pI)ranged from 5.15 to 9.26.Cell-PLoc subcellular localization predictions suggested that all LBD proteins were located in the nucleus.Besides,all LBD protein domains and gene structures were highly conserved and composed of similar motifs.These PmLBDs were divided into 5 categories(Class I ae)according to the phylogenetic tree,containing 4,11,5,1 and 9 genes,respectively.qRT-PCR showed that PmLBDs were expressed in different tissues.For example,PmLBD2/5/18/19 were highly expressed in stems,and PmLBD9/20/23 of Class I b were strongly expressed in lateral roots.The expression of most LBDs strongly responded to salt stress,17 PmLBDs were up-regulated and 6 PmLBDs were down-regulated under salt treatment,and the expression of genes in the same subfamily showed a similar trend.