基于柴胡转录组挖掘高温胁迫响应NAC转录因子

Transcriptome-Based Identification of Heat-Responsive NAC Transcription Factors in Bupleurum Chinense

摘要: 为探究气候变暖背景下柴胡响应高温胁迫的分子机制，本研究以“郑柴胡3号”为实验材料进行高温胁迫与对照处理，结合转录组测序筛选高温响应NAC转录因子，并运用生物信息学方法分析其理化性质、保守基序、系统进化关系及表达模式。结果显示：共鉴定出22个差异表达的柴胡NAC转录因子家族成员，其中11个基因表达上调、11个下调；理化性质分析表明，22个NAC蛋白相对分子质量介于8681.83~60469.14 Da之间，等电点平均值为6.67，22个NAC家族蛋白均属于疏水性蛋白；二级结构分析显示，无规则卷曲和α螺旋占比较大，其中无规则卷曲的平均占比为69.90%，α螺旋的平均占比为13.18%；保守基序分析显示，Motif 2出现频率最高(18个转录因子均含该基序)，Motif 6包含的氨基酸序列最长(49个氨基酸)，22个NAC转录因子可依据基序组合分为5类；系统进化分析表明，柴胡NAC蛋白与拟南芥NAC蛋白存在保守进化关系。本研究基于转录组学系统挖掘柴胡响应高温胁迫NAC转录因子，为鉴定候选的柴胡耐热基因及培育耐高温柴胡新品种提供潜在线索。

Abstract: To investigate the molecular mechanism of Bupleurum chinense responding to high-temperature stress under the background of global warming, the varity “Zheng chaihu 3” was as the experimental material for high-temperature stress and control treatments in this study. Based on transcriptome sequencing data, we screened high-temperature responsive NAC transcription factors, and analyzed their physicochemical properties, conserved motifs, phylogenetic relationships and expression patterns by using bioinformatics methods. The results showed that 22 differentially expressed NAC transcription factor family members in Bupleurum chinense were identified, of which 11 genes were up-regulated and 11 were down-regulated. Physicochemical property analysis indicated that the relative molecular weight of the 22 NAC proteins ranged from 8681.83 Da to 60469.14 Da, with an average isoelectric point of 6.67, and all 22 NAC family proteins were hydrophobic proteins. Secondary structure analysis revealed that random coil and α-helix accounted for a relatively large proportion, among which the average proportion of random coil was 69.90% and that of α-helix was 13.18%. Conserved motif analysis showed that Motif 2 had the highest frequency (present in 18 transcription factors), and Motif 6 had the longest amino acid sequence (49 amino acids). The 22 NAC transcription factors could be divided into five categories according to motif combinations. Phylogenetic analysis indicated that there was a conserved evolutionary relationship between Bupleurum chinense NAC proteins and Arabidopsis thaliana NAC proteins. This study systematically identified high-temperature responsive NAC transcription factors in Bupleurum chinense based on transcriptome data, providing potential clues for the identification of candidate heat-tolerance genes and breeding of new heat-tolerant Bupleurum chinense varieties.