翅果油树油体蛋白基因家族鉴定及其在种子发育中的表达模式分析

Identification of Oleosin gene family in Elaeagnus mollis and analysis of its expression patterns during seed development

关键词:  翅果油树，Oleosin基因家族，系统进化，密码子偏好性，表达模式分析

Key words:  Elaeagnus mollis, Oleosin gene family, phylogenetic analysis, codon usage bias, expression pattern analysis

摘要:

油体蛋白（Oleosin）是油体表面丰度最高的蛋白，调控油脂储存。目前，木本油料植物翅果油树中Oleosin家族的功能及其在油脂合成积累等关键生物学过程中的作用尚未明晰。因此，该研究采用生物信息学方法鉴定翅果油树油体蛋白，并对该基因家族成员理化性质、进化关系、系统发育、保守基序、顺式作用元件结构特征、密码子偏好性和基因表达模式进行了系统的分析，结果表明：（1）从翅果油树的基因组中鉴定出8个Oleosin基因，根据其在染色体上的位置命名为EmoOLE1-EmoOLE8。（2）系统进化树、保守基序和基因结构分析显示，8个EmoOLE基因被划分为3个亚家族。（3）EmoOLE基因除核心启动子元件（TATA-box和CAAT-box）外，共鉴定出22类功能各异的调控元件，依据其生物学功能划分为光响应、植物激素响应、生长发育调控以及非生物胁迫响应4大类。（4）密码子偏好性分析显示，该基因家族密码子偏好以A/T碱基结尾，4个密码子无偏好性，27个有偏好性。（5）基于翅果油树4个发育阶段的种子转录组及种子中三酰甘油、二酰甘油含量，表达谱分析显示EmoOLE在种子成熟期表达上调，qRT-PCR证实了这一结果；相关性分析结果表明，7个EmoOLE基因（EmoOLE1、EmoOLE3、EmoOLE4、EmoOLE5、EmoOLE6、EmoOLE7和EmoOLE8）的表达水平与三酰甘油或二酰甘油合成积累显著正相关。综上，该研究结果为深入解析翅果油树Oleosin基因家族的功能及其高含油量分子育种提供了理论基础。

Abstract:

Oleosin is the most abundant structural protein localized on the surface of oil bodies and serves a critical function in regulating lipid storage. Currently, the functions of the Oleosin gene family in the woody oilseed plant Elaeagnus mollis, particularly its roles in regulating key biological processes such as lipid biosynthesis and accumulation, remain unclear. Therefore, this study employed bioinformatics methods to identify Oleosin genes in E. mollis and systematically analyzed the physicochemical properties, protein structures, conserved motifs, phylogenetic relationships, cis-regulatory element structures, codon usage bias, and gene expression patterns of the gene family members. The results demonstrated that: (1) A total of 8 Oleosin genes were identified from the E. mollis genome and were designated EmoOLE1 to EmoOLE8 according to their chromosomal order. (2) Phylogenetic analysis, together with conserved motif and gene structure examination, classified the 8 EmoOLE genes into three distinct subfamilies. (3) In addition to core promoter elements such as TATA-box and CAAT-box, a total of 22 types of cis-regulatory elements were identified in the promoters of EmoOLE genes. These elements were categorized into four major functional modules: light response, phytohormone response, growth and development, and abiotic stress response. (4) Analysis of codon usage bias indicated that the EmoOLE gene family exhibits a strong preference for A/T-ended codons. Among them, 4 codons exhibited no significant bias, while 27 codons exhibited clear usage bias. (5) Based on the transcriptome data of the seeds at 4 developmental stages and the contents of triacylglycerol (TAG) and diacylglycerol (DAG), which demonstrated that EmoOLE expression was upregulated during seed maturation, and this result was also confirmed by qRT-PCR. Furthermore, correlation analysis revealed that 7 EmoOLE genes (EmoOLE1、EmoOLE3、EmoOLE4、EmoOLE5、EmoOLE6、EmoOLE7 and EmoOLE8) displayed significant positive correlations with TAG or DAG accumulation, suggesting their crucial roles in lipid storage in E. mollis seeds. In conclusion, these findings establish a theoretical foundation for further functional studies and support molecular breeding initiatives aimed at enhancing oil content in this economically important woody oil species.