龙眼FLOE基因家族鉴定、亚细胞定位及表达分析

Identification, subcellular localization, and expression analysis of longan FLOE gene family

  • 摘要:目的】对龙眼FLOE基因家族成员进行鉴定、亚细胞定位及表达分析,探究FLOE基因家族成员在龙眼体胚发生过程与胁迫响应中的作用机理,为龙眼抗逆分子育种提供理论依据。【方法】以拟南芥FLOE家族蛋白序列作为参考序列,从龙眼基因组中鉴定出DlFLOE基因家族成员,利用生物信息学方法对其进行序列特征分析,并采用实时荧光定量PCR检测DlFLOE基因家族在体胚发生早期不同阶段以及不同激素和非生物胁迫处理下的表达模式。【结果】共鉴定出3个DlFLOE基因家族成员,按照其在染色体上的位置分别命名为DlFLOE1DlFLOE2DlFLOE3;DlFLOE基因家族成员编码的氨基酸数量介于440~559,相对分子质量介于48.36~61.25 kD,理论等电点介于5.51~6.16,均为亲水性且不稳定的蛋白;DlFLOE2蛋白定位于液泡,DlFLOE1和DlFLOE3蛋白均定位于细胞核。系统发育分析结果显示,DlFLOE3基因与荔枝LITCHI022451.m1基因聚为一支,表明无患子科同源基因具有保守性。基因结构与蛋白结构及共线性分析结果显示,DlFLOE2基因含5个内含子,其余基因均含2个内含子,内含子长度存在物种间差异;绝大多数成员含有DUF1421结构域;DlFLOE2DlFLOE3基因间存在共线性关系,2个基因分别位于不同的染色体,且Ka/Ks=0.261,说明其在进化过程中受到纯化选择作用。启动子顺式作用元件与亚细胞定位分析结果显示,DlFLOE家族成员启动子均含有光响应、干旱胁迫响应等元件;DlFLOE1基因对高浓度PEG表现出强烈的正向响应,且该基因定位于细胞核中,与在线软件预测结果一致。实时荧光定量PCR检测结果显示,DlFLOE基因家族成员对不同激素和非生物胁迫处理均有响应,但表达模式存在差异。【结论】从龙眼基因组中鉴定出的3个FLOE基因家族成员存在功能分化,且具有明显的时空特异性,在龙眼逆境响应和激素调节中发挥重要作用,尤其是DlFLOE1基因对高浓度PEG表现出强烈的正向响应,推测其参与抗旱相关通路。

     

    Abstract:Objective】This study aimed to perform identification, subcellular localization, and expression analysis of the longan FLOE gene family members, explore the mechanism underlying the FLOE gene family during longan somatic embryogenesis and stress response, providing theoretical reference for molecular breeding of stress-tolerant longan.【Method】Using the Arabidopsis thaliana FLOE family protein sequences as reference sequences, DlFLOE gene family members were identified from longan genome. Bioinformatic methods were employed to analyze their sequence characteri-stics. Real-time fluorescence quantitative PCR was utilized to analyze different early stages of somatic embryogenesis and expression patterns under hormones and abiotic stresses of DlFLOE gene family.【Result】Three DlFLOE gene family members were identified and named DlFLOE1DlFLOE2, and DlFLOE3 according to their positions on chromosomes. The number of amino acids encoded by DlFLOE family members ranged from 440 to 559, with relative molecular mass ranged from 48.36 to 61.25 kD, and theoretical isoelectric points of 5.51-6.16, indicating that they were all hydrophilic and unstable proteins. The DlFLOE2 protein located in the vacuole, while DlFLOE1 and DlFLOE3 proteins were located in nucleus. Phylogenetic analysis results showed that the DlFLOE3 gene clustered with the LITCHI022451.m1 gene of Litchi chinensis, indicating that the homologous genes of Sapindaceae were conserved. According to results of gene and protein structure analysis as well as collinearity analysis, the DlFLOE2 gene had five intron, and the rest genes contained two introns, with intron length showing difference between species; most members contained DUF1421 domain; a colli-near relationship was found between DlFLOE2 and DlFLOE3 genes, with the two genes located on different chromosomes and the Ka/Ks=0.261, suggesting that they had been under purifying selection during evolution. Promoter cis-element analysis and subcellular localization results showed that the promoters of DlFLOE family members contained elements responsive to light and drought stress; the DlFLOE1 gene had a strong positive response to high-concentration PEG and was located in nucleus, which was consistent with predictions from online software. Real-time fluorescence quantitative PCR detection results indicated that DlFLOE genes family members responded to different hormones and abiotic stress treatments, but their expression patterns varied.【Conclusion】The three FLOE gene family members identified from the longan genome exhibit functional differentiation and clear spatiotemporal specificity, showing important roles in stress response and hormone regulation for longan. The DlFLOE1 gene shows a strong positive response to high-concentration PEG, thus, it is suggested to be involved in drought-responsive pathways.

     

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