菠菜SoNAC转录因子家族的全基因组鉴定与分析

Genome-wide identification and analysis of spinach SoNAC transcription factor family

采用生物信息学分析方法,从菠菜基因组中筛选鉴定了57个菠菜NAC转录因子,并对其基因结构、编码蛋白和系统进化进行了分析;通过荧光定量聚合酶链式反应qRT-PCR分析,研究了高温和盐处理后菠菜叶片中NAC基因的表达模式.研究结果显示:菠菜NAC转录因子可以被归入2组17个亚组,GroupⅠ包含10个亚组,GroupⅡ包含7个亚组;染色体定位分析表明,共有36个SoNACs基因随机分布在菠菜的6个染色体上,其中21个分布在scaffold上,多数基因位于端粒,部分基因在染色体上成簇分布并具有相似的结构;基序分析表明,SoNACs中存在5个高度保守的基序,其中没有一个基序是所有SoNACs都共有,有些亚族(SND)的保守基序被其他基序替换,进一步对保守基序的预测表明,Motif 1,2和3是NAM结构域中的核心基序.为揭示NAC家族在菠菜中的抗逆作用,通过qRT-PCR分析了不同亚族SoNACs基因在高温和盐胁迫下的基因表达,许多基因被盐分或高温胁迫上调或下调,不同胁迫下存在显著差异表达模式.盐胁迫下,SoNACs表达模式聚为2类:一类为表达上调、在转录中后期发挥主要作用的成员(SoNAC34,SoNAC35,SoNAC51,SoNAC57);另一类为表达下调,但有2个成员(SoNAC45,SoNAC50)在转录起始阶段发挥主要作用的SoNACs;高温胁迫下,SoNACs表达模式聚为3类:第一类为表达上调、在转录中后期发挥主要作用的成员(SoNAC57);第二类为表达下调的成员;第三类为表达上调不明显的成员.与高温胁迫相比,盐胁迫下更多SoNACs基因倾向于高表达,SoNAC57是响应两种胁迫均被上调的基因.因此,进一步对该基因及其亚组成员进一步分析可能有助于建立菠菜的胁迫耐受性.

In this study,bioinformatics analysis was used to screen and identify 57 spinach NAC transcription factors from the spinach genome,and to analyze their gene structures,encoded proteins and phylogenetic evolution.Meanwhile,by using quantitative fluorescence PCR(qRT-PCR),expression patterns of NAC genes were examined in spinach leaves treated by high temperature and salt stress.The results of this study showed that spinach NAC transcription factors were classified into 2 groups and 17 subgroups.Groups I and II consisted of 10 and 7 subgroups,respectively.Chromosome location analysis showed that 36 SoNACs genes were randomly distributed on six spinach chromosomes,and among them,21 genes were distributed on scaffolds,most of genes were located in telomeres,and some genes were clustered on chromosomes with similar structures.In addition,motif analysis showed that,there are 5 highly conserved motifs in SoNACs,none of which is common to all SoNACs,and some subfamilies(SNDs)of conserved motifs are replaced by other motifs.Further prediction of conserved motifs shows that Motifs 1,2 and 3 are core motif in the NAM domain.In order to reveal the stress resistance of NAC family in spinach,the gene expression of different SoNAC subfamilies under conditions of high temperature and salt stress was analyzed by qRT-PCR.The results showed that many genes were up-regulated or down-regulated by salt or high temperature stress,indicating there were significant different expression patterns under different stresses.Under salt stress,the expression patterns of SoNACs are clustered into two categories,one is the up-regulated members(SoNAC34,SoNAC35,SoNAC51,SoNAC57)that function mainly in the middle and late stages,and the other is down-regulated members(SoNAC45,SoNAC50)that work mainly in the initiation stage.By comparison,under high temperature stress,the expression patterns of SoNACs are clustered into three categories,the first category is the up-regulated member(SoNAC57)that functions mainly in the middle and later stages,the second category is down-regulated member,and the third group is the member whose expression is not significantly up-regulated.Compared with high temperature stress,more SoNACs genes tend to be highly expressed under salt stress.However,SoNAC57 is a gene that is up-regulated in response to both stresses.As a consequence,further analysis of this gene and its subgroup members may help to establish stress tolerance in spinach.