核桃SPL基因家族的系统进化和表达分析

Phylogenetic Evolution and Expression Analysis of SPL Gene Family in Juglans regia

【目的】SQUAMOSA promoter binding protein-like(SPL)转录因子在植物开花诱导中起重要的调控作用。从核桃基因组中鉴定SPL(JrSPL)基因家族成员并分析其表达特性,为探究SPL在核桃开花诱导中的功能研究提供参考。【方法】采用生物信息学方法鉴定JrSPL基因家族成员,并预测其基本理化性质、保守结构域、进化关系、启动子顺式作用元件等;利用转录组测序和RT-qPCR技术分析JrSPL家族成员在核桃不同组织及嫁接诱导开花后的表达水平。【结果】JrSPL家族有28个成员,其基因结构和蛋白结构均高度保守,分布在核桃14条不同的染色体,与拟南芥和毛果杨分别存在17处和24处共线性关系,根据系统发育关系可分为8组。JrSPL启动子存在大量的光响应元件、激素应答元件、胁迫响应元件等。转录组测序分析显示,JrSPL基因在核桃不同组织表达量有差异,在雄花、雌花、顶芽及叶中均有表达,多数基因在雌花中的表达量都比较高,有6个基因最为显著,它们可能在开花诱导中起关键作用。在嫁接诱导核桃开花材料中,检测的12个JrSPLs中除了JrSPL8外,在开花材料中的表达量均高于对照,JrSPL2和JrSPL25在混合花序的雄花中表达显著,JrSPL8在顶芽中高表达。【结论】JrSPL基因在核桃成花中具有重要作用,其高表达是花期提前的主要因素。

【Objective】The SQUAMOSA promoter binding protein like(SPL)transcription factor is a crucial regulatory element in the induction of plant flowering.This study aims to identify the members of the SPL(JrSPL)gene family within the walnut genome and analyze their expression characteristics.The findings of this study will serve as a valuable reference for further investigations into the functional aspects of SPL in walnut flowering induction.【Method】The present study employed bioinformatics techniques to identify members of the JrSPL gene family,subsequently to predict their fundamental physicochemical properties,conserved domains,evolutionary relationships,and cis acting elements of promoters.Additionally,transcriptome sequencing and RT-qPCR technology were employed to investigate the expressions of JrSPL family members in various tissues of walnut,as well as following grafting-induced flowering.【Result】The JrSPL family consisted of 28 members,showing significant conservation in their gene and protein structures,which were dispersed across 14 distinct chromosomes within the walnut genome.Notably,there were 17 collinear relationships with Arabidopsis and 24 with Populus tomentosa,respectively.Through phylogenetic analysis,these members were categorized into 8 distinct groups.Additionally,the JrSPL promoter region encompassed a substantial quantity of light responsive elements,hormone responsive elements,stress responsive elements,and other similar regulatory motifs.The transcriptome analysis revealed that the JrSPL genes demonstrated varying expressions across different tissues of walnut,including male flowers,female flowers,apical buds,and leaves.Notably,the expressions of most genes were relatively high in female flowers,with 6 genes having significant expression,suggesting their potential involvement in the induction of flowering.In the context of grafting-induced walnut flowering materials,with the except of JrSPL8,the expressions of 12 JrSPLs observed in the flowering materials were found to be greater than those in the control group.Specifically,JrSPL2 and JrSPL25 showed significant expressions in the male flowers of mixed inflorescences,whereas JrSPL8 had high expression in the apical buds.【Conclusion】The JrSPL gene exerts a significant influence on the process of walnut flowering,with its high expression serving as the primary determinant of early flowering.