甘薯全基因组WRKY转录因子的基因鉴定与逆境胁迫表达分析

Identification of WRKY transcription factor genes in Ipomoea batatas genome and expression analysis under stresses

【目的】对甘薯(Ipomoea batatas)全基因组WRKY转录因子进行基因鉴定与逆境胁迫表达分析,为甘薯WRKY基因的应用提供参考。【方法】在甘薯全基因组序列的基础上,应用生物信息学方法对WRKY基因进行挖掘,分析基因潜在复制关系、保守结构域、亚家族系统进化树、保守基序和抗逆表达模式,并对甘薯SPF1基因与IbWRKY基因进行了比较和分析。【结果】甘薯全基因组上共有82个WRKY基因,可分为Ⅰ、Ⅱ和Ⅲ3个类型,其中类型Ⅰ和类型Ⅲ的成员数量分别为18和5,类型Ⅱ可进一步分为Ⅱ-a、Ⅱ-b、Ⅱ-c、Ⅱ-d和Ⅱ-e 5个亚类,其成员数量分别为4,14,20,8和13。甘薯WRKY基因不均匀分布于15条染色体上,其中25对基因存在潜在复制关系。保守结构域分析发现,大部分WRKY的结构域高度保守,但个别基因存在保守结构域缺失现象。拟南芥与甘薯的WRKY转录因子在系统进化树上呈现按物种少量聚集的现象。在甘薯WRKY转录因子家族中共发现10个保守基序,包括含有WRKY七肽结构域的基序1和基序7、含有锌指结构域的基序2和基序3,其中基序3为Ⅰ类型WRKY转录因子N端WRKY结构域所特有。对逆境胁迫下的甘薯转录组数据进行分析发现,甘薯苗期在蔓割病菌(Fusarium oxysporum f.sp.batatas)侵染后共有19个WRKY基因差异表达,甘薯块根贮藏期在低温胁迫下有34个WRKY基因差异表达。蛋白序列比较和分析结果表明,甘薯SPF1的氨基酸序列与IbWRKY32的氨基酸序列一致度最高,为85.4%。【结论】甘薯全基因组中鉴定得到82个WRKY基因,其结构域较为保守,在蔓割病胁迫与低温胁迫条件下均存在差异表达。

【Objective】This study conducted gene identification on the WRKY transcription factors of sweet potato(Ipomoea batatas)and analyzed the expression under stresses to provide reference for the application of sweet potato WRKY genes.【Method】Based on the whole genome sequence of sweet potato,bioinformatics methods were used to mine WRKY genes and analyze their potential duplication relationship,conservative domain,subfamily phylogenetics,conservative motif and expression pattern under stress.Further,SPF1 gene and IbWRKY genes were compared.【Result】A total of 82 WRKY genes were identified within the sweet potato genome.The WRKY genes were classified into three subfamilies of subfamily-Ⅰ,subfamily-Ⅱand subfamily-Ⅲ.The numbers in subfamily-Ⅰand subfamily-Ⅲwere 18 and 5,respectively.Subfamily-Ⅱcould be further categorized into five subgroups ofⅡ-a,Ⅱ-b,Ⅱ-c,Ⅱ-d andⅡ-e with the numbers of 4,14,20,8 and 13,respectively.The WRKY genes distributed unevenly on the 15 chromosomes of sweet potato,among which 25 pairs showed potential duplication relationship.Most of the WRKY domains were highly conserved,and conservative domain deletion was observed in only several WRKY proteins.The WRKY transcription factors of Arabidopsis thaliana and I.batatas showed clustering characteristics.Ten conserved motifs were found in sweet potato WRKY transcription factor family,including motif 1 and motif 7 with WRKY heptapeptide domain and motif 2 and motif 3 with zinc finger domain.The motif 3 was unique to the N-terminal WRKY domain of subfamily-ⅠWRKY transcription factors.The analysis on transcriptomics data of sweet potato under stress showed that 19 WRKY genes were differentially expressed after Fusarium oxysporum f.sp.batatas infection at seedling stage,and 34 WRKY genes were differentially expressed during storage period of sweet potato tuber roots under low temperature stress.The comparison and analysis of protein sequences showed that sweet potato SPF1 gene shared the highest identity of amino acid sequence(85.4%)with the IbWRKY32 identified in this study.【Conclusion】There were 82 WRKY genes identified in the whole genome of sweet potato with conserved domains.The sweet potato WRKY genes expressed differentially under the stresses of F.oxysporum f.sp.batatas and low temperature.