【摘要】 【目的】分析三峡库区消落带水桦在水淹胁迫下的差异表达基因（DEGs）及关键代谢通路，为阐明水桦抗水淹胁迫的分子机制及消落带苗木选育提供理论依据。【方法】以三峡库区消落带（万州段）栽培的水桦为试验材料，采集水淹约70和200 d的枝条（分别标记为FB70d和FB200d）和根系（分别标记为FR70d和FR200d），并以同期未被水淹的枝条（分别标记为CB70d和CB200d）和根系（分别标记为CR70d和CR200d）为对照，进行转录组测序，筛选CR70d vs FR70d组、CR200d vs FR200d组、CB70d vs FB70d组和CB200d vs FB200d组4个比较组的DEGs，对DEGs进行功能注释及KEGG信号通路富集分析并构建蛋白互作网络。对6个DEGs进行实时荧光定量PCR检测，验证转录组测序数据的可靠性。通过不同浓度乙烯喷施水桦离体枝条研究乙烯对水桦枝条的抗逆影响。【结果】在24个样本中共获得155.99 Gb的有效序列，GC含量为46.00%～48.00%,Q30>92.44%;4个比较组中共筛选出10020个DEGs，其中4389个DEGs上调表达，5631个DEGs下调表达。CB200d vs FB200d组和CB70d vs FB70d组中共有956个DEGs,CR200d vs FR200d组和CR70d vs FR70d组中共有17个DEGs。共有7220个DEGs被注释到生物过程、分子功能和细胞组分三大功能类别上。KEGG信号通路富集分析结果显示，植物激素信号转导通路是DEGs富集最明显的通路。有4个DEGs编码蛋白参与的蛋白调控网络最多。4个比较组中，植物激素信号转导通路共有的基因为35个，其中CR200d vs FR200d组和CB200d vs FB200d组的表达发生改变的基因最多，分别有24和32个。乙烯激活因子基因（ERF1和ERF2）在CB70d vs FB70d组和CB200d vs FB200d组表达上调，而在CR70d vs FR70d组和CR200d vs FR200d组无变化。在ABA生物合成通路中，除CR70d vs FR70d组外，SnRK2基因在其他3个比较组均表达下调。大部分基因的转录组测序结果与实时荧光定量PCR检测结果的变化趋势一致。不同浓度乙烯处理10 d后，与对照相比，3个不同浓度乙烯处理下水桦枝条均能保持幼嫩的生长状态。【结论】水淹后水桦枝条基因对胁迫的响应敏感性高于根系。在植物激素信号转导关键信号通路上，筛选到2个响应水淹胁迫的乙烯激活因子基因（ERF1和ERF2）用于下一步功能验证研究。更多还原

【Abstract】 【Objective】This study aimed to analyze the differentially expressed genes(DEGs) and key metabolic pathways of Betula nigra under flooding stress in the Three Gorges Reservoir Area, so as to provide theoretical basis for elucidating the molecular mechanism of Betula nigra’s resistance to flooding stress and the seedling selection of s in reservoir area. 【Method】Using Betula nigra cultivated in the Three Gorges Reservoir Area(Wanzhou Section) as experimental materials, branches(labeled FB70d and FB200d respectively) and roots(labeled FR70d and FR200d respectively) that were flooded for 70 d and 200 d were collected. Branches(labeled CB70d and CB200d respectively) and roots(labeled CR70d and CR200d respectively) that were not flooded during the same period were used as controls. Transcriptome sequencing was performed to screen DEGs in the four comparison groups: CR70d vs FR70d group, CR200d vs FR200d group, CB70d vs FB70d group, and CB200d vs FB200d group. Functional annotation and KEGG signaling pathway enrichment analysis were performed, and a protein interaction network was constructed. Real-time fluorescence quantitative PCR detection of 6 genes were performed to verify the data reliability of transcriptome sequencing. Effects of ethylene on stress resistance of Betula nigra branches were investigated by spraying ethylene at different concentrations on detached branches. 【Result】A total of 155.99 Gb of effective sequences were obtained from 24 samples, with a base GC content ranging from 46.00% to 48.00%, Q30>92.44%;A total of 10020 DEGs were screened from the four comparison groups, of which 4389 DEGs were up-regulated and 5631 DEGs were down-regulated. The CB200d vs FB200d group and CB70d vs FB70d group had a total of 956 DEGs; the CR200d vs FR200d group and CR70d vs FR70d group had 17 DEGs. A total of 7220 DEGs were annotated into three major functional categories: biological processes, molecular functions, and cellular components. KEGG signaling pathway enrichment analysis results showed that the plant hormone pathway was the pathway with the most obvious enrichment of DEGs. Four DEG-encoded proteins participated in the majority of the protein regulatory networks. In the four comparison groups, the plant hormone signaling pathway shared 35 genes. The CR200d vs FR200d group and CB200d vs FB200d group had the most genes with altered expression, with 24 and 32 genes, respectively. The ethylene activating factor genes(ERF1 and ERF2) were up-regulated in the CB70d vs FB70d group and CB200d vs FB200d group, while the genes did not change in the CR70d vs FR70d group and CR200d vs FR200d group. In the ABA biosynthesis pathway, except for the CR70d vs FR70d group, the SnRK2 gene was downregulated in the other three comparison groups. The transcriptome sequencing results of most genes were consistent with the variation trend of test results of real-time fluorescence quantitative PCR. After 10 d of treatments with ethylene at different concentrations, compared with the control, three treatment groups could help Betula nigra branches keep tender. 【Conclusion】After flooding, the response sensitivity of genes of Betula nigra branches to stress turn higher than that of the root system. Two ethylene-activating factor genes(ERF1 and ERF2) responding to flooding stress are selected for further research functional verification.更多还原