辣椒CaERF4的全长cDNA克隆及其表达分析

Full Length cDNA Cloning and Expressional Characterization of CaERF4 of Capsicum annuum

通过筛选辣椒均一化cDNA文库，获得一个具有AP2结构域的辣椒CaERF4全长cDNA序列，含有一个编码250个氨基酸序列的开放阅读框,与拟南芥等其它植物ERF蛋白之间有35％～38％的氨基酸序列相似性。该基因在辣椒不同器官中均有不同程度的组成型表达，在根系中表达量略低。此外，还发现CaERF4的转录受到茉莉酸甲酯（MeJA）和乙烯利（ETH）等外源激素处理以及青枯菌接种的诱导，但水杨酸（SA）处理作用不明显，高温处理也可诱导其转录表达增强。说明CaERF4可能在辣椒应答病原菌和高温等逆境胁迫中起调节作用。

ERF（Ethylene Responsive Factor） is an important plant specific transcription factor family implicated in plant growth, development and response to environmental stresses. However, the structure and function of the major members in this family remain unknown, especially in non model plants such as Capsicum annuum. In the present study, a full length cDNA of putative ERF containing AP2 conservative domain was identified from randomly sequencing of a normalized cDNA library of pepper. This full length cDNA harbors an open reading frame encoding a protein of 250 aa in length sharing 35%-38% sequence identity to ERFs from other plant species. The putative ERF transcription factor was designated as CaERF4 due to its highest sequence identity to A tCRF4. By RT-PCR analysis, CaERF4 exhibited a constitutive transcriptional expression in different organs in pepper plants, and it was also found to be induced to different degree by exogenously applied ETH and MeJA as well as by inoculation of Ralstonia solanacearum and treatment of high temperature stress, but not by exogenous application of SA. These results implied that CaERF4 may play key roles in pepper response to R. solanacearum inoculation and heat stress treatment.