王奇 李晓旭 郭存 郭永峰

摘 要：NAC家族是植物中最大的转录因子家族之一，在植物生长发育以及应对环境胁迫中起着至关重要的作用，克隆和验证烟草中NAC相关基因可为烟草抗性育种提供理论依据。本研究采用RT-PCR方法从普通烟草K326根部cDNA中克隆到NtNAC055基因，对NtNAC055及其编码蛋白进行了生物信息学分析、表达模式分析、亚细胞定位和转录激活等相关试验。结果发现，NtNAC055基因的CDS序列全长为1032 bp，NtNAC055蛋白具有典型的NAC结构域，编码一个具有343个氨基酸的NAC转录因子;通过进化分析发现，烟草NtNAC055与拟南芥ANAC055同源性较高，同属于RD26亚家族;通过亚细胞定位分析以及转录激活分析发现，NtNAC055蛋白在细胞核中且具有转录激活活性;运用qRT-PCR技术，对该基因不同组织和胁迫处理后的表达进行了分析，结果显示，NtNAC055基因在根、茎、叶、花和腋芽中均有表达，且在根部表达量最高;同时，该基因受干旱和热胁迫的诱导，表明烟草NtNAC055基因可能参与了烟草的非生物胁迫应答反应。

关键词：烟草;NtNAC055;非生物胁迫;干旱;基因表达

Abstract： NAC family is one of the largest transcription factor families in plants， and plays a significant regulatory role in plant development， signal transduction and abiotic stress response. Cloning and validation of NAC related genes in tobacco can provide a theoretical basis for tobacco breeding for stress tolerance. In this study， NtNAC055 was cloned from root cDNA of cv. K326 by RT-PCR. In addition， bioinformatics analysis， expression pattern analysis， subcellular localization and transactivation activity analysis of NtNAC055 were performed. The results showed that the full-length of NtNAC055 was 1032 bp， and the NtNAC055 protein was 343 aa that contained a typical NAC domain. Phylogenetic analysis indicated that NtNAC055 had high homology with ANAC055 from Arabidopsis. Subcellular localization and transactivation analyses showed that NtNAC055 was localized in the nucleus and had transactivation activities. The expressions of NtNAC055 were analyzed by qRT-PCR in different tissues of tobacco， and in seedlings under different abiotic stresses. The results showed that NtNAC055 was expressed in tobacco roots， stems， leaves， flowers and axillary buds， especially in roots. The expression levels of NtNAC055 were induced under drought and heat stresses， which indicated that NtNAC055 might be involved in tobacco abiotic stress responses.

Keywords： tobacco; NtNAC055; abiotic stress; drought; gene expression

NAC（NAM， AFAT， CUC）转录因子是植物特有的一类转录因子[1]，SOUER等[2]从矮牵牛中克隆到第一个NAC转录因子NAM（No Apical Meristem），该转录因子家族成员作为重要的调控因子广泛参与了植物生长发育过程，包括叶片衰老[3-4]，侧根发育[5-7]，果实成熟[8]，次生壁形成[9-10]和植物激素信号转导[11-13]等。同时，有很多文献报道NAC转录因子家族成员在植物响应非生物胁迫中也发挥着重要的作用[14]。过表达ANAC072、ANAC019和ANAC055基因时，转基因拟南芥植株的耐旱性显著提高[15]，并可以促进拟南芥干旱应答基因的表达。……