药用植物长春花WRKY转录因子的鉴定及表达谱分析

Identification and expression analysis of WRKY transcription factors in medicinal plant Catharanthus roseus

摘要:

WRKY是调控植物生长发育和逆境胁迫反应等生命活动的一个转录因子大家族。然而，有关药用植物长春花CrWRKY转录因子的种类和功能却知之甚少。从26 009个长春花蛋白中鉴定出47个CrWRKY转录因子。依据WRKY结构域和系统进化，将CrWRKY分为G1、G2和G3三大类群。表达谱数据分析表明，长春花CrWRKY基因的表达具有器官特异性。47个CrWRKY基因的表达谱可分为3种表达模式：第1类型主要在花、甲基茉莉酸甲酯 (MeJA) 或酵母提取物 (YE) 处理的原生质体中高表达；第2类型主要在茎和毛状根中高表达；第3类型在根、茎、叶、幼苗和MeJA处理的毛状根中高表达。进一步用实时定量PCR检测了16个代表性CrWRKY基因在不同器官、MeJA处理原生质体和毛状根中的表达模式，检测结果与上述数字基因表达谱数据基本一致。约1/3以上CrWRKY基因的表达受MeJA和YE的调控，暗示它们可能参与萜类吲哚生物碱的合成和逆境胁迫反应。为进一步解析长春花WRKY转录因子的功能和萜类吲哚生物碱合成调控的网络奠定了基础。

Abstract:

WRKY transcription factors, one of the largest families of transcriptional regulators in plants, involve in multiple life activities including plant growth and development as well as stress responses. However, little is known about the types and functions of WRKY transcription factors in Catharanthus roseus, an important medicinal plant. In this study, we identified 47 CrWRKY transcriptional factors from 26 009 proteins in Catharanthus roseus, and classified them into three distinct groups (G1, G2 and G3) according to the structure of WRKY domain and evolution of the protein family. The expression profiling showed that these CrWRKY genes expressed in a tissue /organ specific manner. The 47 CrWRKY genes were clustered into three types of expression patterns. The first type includes the CrWRKYs highly expressed in flowers and the protoplast treated with methy jasmonate (MeJA) or yeast extraction (YE). The second type contains the CrWRKYs highly expressed in stem and hairy root. The third type represents the CrWRKYs highly expressed in root, stem, leaf, seedling and the hairy root treated by MeJA. Real time quantitative PCR was employed to further identify the expression patterns of the 16 selected CrWRKY genes in various organs, the MeJA-treated protoplasts and hairy roots of Catharanthus roseus, and similar results were obtained. Notably, the expresion of more than 1/3 CrWRKY genes were regulated by MeJA or YE, indicating that these CrWRKYs are likely involed in the signalling webs which modulate the biosynthesis of terpenoid indole alkaloid and plant responses to various stresses. The present results provide a framework for functional identification of the CrWRKYs and understanding of the regulation network of terpenoid indole alkaloid biosynthesis in Catharanthus roseus.