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萼距花NAC基因家族鉴定及冷胁迫响应表达分析

Identification of the NAC Gene Family in Cuphea hookeriana and Analysis of Its Expression in Response to Cold Stress

  • 摘要: 为探究萼距花NAC转录因子家族特征及其在冷胁迫响应中的表达调控机制,挖掘关键抗寒基因。基于全基因组数据,系统鉴定NAC基因家族成员,分析其理化性质、系统进化、基因结构、保守基序、染色体分布及共线性关系;利用转录组测序与qRT-PCR技术,分析ChNAC基因在冷胁迫不同时间点的表达动态。结果共鉴定出218个ChNAC基因,不均匀分布于16条染色体,系统进化显示其可分为16个亚族,NAC2亚族成员最多;共线性分析发现2129对重复基因对,串联重复事件6组,Ks分布曲线呈现0.03和0.63两个显著峰值;启动子分析发现ChNAC基因富含脱落酸响应(ABRE)等顺式作用元件;冷胁迫表达分析显示,18个ChNAC基因在冷胁迫12 h显著高表达,其中ChNAC1ChNAC24ChNAC130ChNAC215ChNAC217这5个基因经qRT-PCR验证表达趋势与转录组数据一致。综合表明,ChNAC基因家族在进化中经历多次复制扩张,多个成员受冷胁迫显著诱导表达,其中5个基因可能作为冷胁迫响应的核心调控因子。

     

    Abstract: This study aimed to investigate the characteristics of the NAC transcription factor family in Cuphea hookeriana and its regulatory mechanisms in response to cold stress, as well as to identify key cold-tolerance genes. Based on whole-genome data, NAC gene family members were systematically identified, and their physicochemical properties, phylogenetic relationships, gene structures, conserved motifs, chromosomal distribution, and syntenic relationships were analyzed. The expression dynamics of ChNAC genes at different time points under cold stress were examined using transcriptome sequencing and qRT-PCR. A total of 218 ChNAC genes were identified, unevenly distributed across 16 chromosomes. Phylogenetic analysis showed that they could be divided into 16 subfamilies, with the NAC2 subfamily containing the most members. Synteny analysis revealed 2,129 duplicated gene pairs and six tandem duplication events, and the Ks distribution curve exhibited two significant peaks at 0.03 and 0.63. Promoter analysis indicated that ChNAC genes are enriched in cis-acting elements such as abscisic acid-responsive (ABRE) elements. Expression analysis under cold stress showed that 18 ChNAC genes were significantly upregulated at 12 h of stress, among which five genes—ChNAC1, ChNAC24, ChNAC130, ChNAC215 and ChNAC217—were validated by qRT-PCR, showing expression trends consistent with the transcriptomic data. In conclusion, the ChNAC gene family in C. hookeriana has undergone multiple duplication events during evolution, and several members are significantly induced by cold stress. Among them, these five genes may serve as core regulatory factors in the cold stress response, providing an important basis for elucidating the molecular mechanisms of cold tolerance in C. hookeriana.

     

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