油菜脯氨酸代谢基因家族的生物信息学分析与核心成员鉴定

Bioinformatics analysis and core member identification of proline metabolism gene family in Brassica napus L.

脯氨酸积累是植物在生物和非生物胁迫下的一种重要的代谢适应性机制。吡咯啉-5-羧酸合成酶(P5CS)、吡咯啉-5-羧酸还原酶(P5CR)酶、脯氨酸脱氢酶(PDH)、吡咯啉-5-羧酸脱氢酶(P5CDH)是依赖谷氨酸的脯氨酸生物合成途径中的关键酶。油菜是世界上重要的油料作物,在油菜生长发育过程中,其时常遭受各类生物和非生物胁迫。然而迄今为止,在异源四倍体油菜中缺乏关于这些脯氨酸代谢基因家族的系统分析报道。本研究利用甘蓝型油菜‘中双11’基因组注释信息,分别鉴定到上述10个BnaP5CSs、6个BnaP5CRs、8个BnaPDHs以及3个BnaP5CDHs基因。这些基因家族在系统发育上分为不同的进化分支,同一亚组中的成员具有相似的理化特性、基因/蛋白质结构和保守的基序。进化压力分析表明,这些基因均遭受了强烈的纯化选择。启动子区的顺式作用元件分析揭示了油菜上述4类基因家族之间均存在共同的和特异的转录调控机制。本研究分别对‘中双11’油菜幼苗进行盐胁迫、低钾、低磷以及铵毒胁迫处理,分别取地上部及根部进行转录组测定与分析。结果显示,脯氨酸合成相关基因的表达水平在上述4种胁迫下普遍上调,而调控脯氨酸降解基因的表达水平则在盐胁迫和低磷胁迫情况下调;基因共表达分析显示BnaC4.P5CS1a、BnaA5.P5CS1等基因可能在脯氨酸介导的油菜逆境响应网络中发挥核心作用。本研究通过脯氨酸代谢基因家族的生物信息学鉴定以及多种非生物逆境下的转录特征分析,将为深入研究脯氨酸介导的逆境抗性提供理论依据,也将为脯氨酸介导油菜非生物胁迫抗性的遗传改良提供优异的基因资源。

Proline accumulation is an important metabolic adaptative mechanism of plants under biotic and abiotic stress.P5CS,P5CR,PDH,and P5CDH are key enzymes in the glutamate-dependent proline biosynthesis pathway.Rapeseed,an important oil crop in the world,is often subjected to various biotic and abiotic stresses during its growth and development.However,no systematic analysis of these proline metabolic gene families has been reported in Brassica napus so far.In this study,10 BnaP5CSs,6BnaP5CRs,8 Bna PDHs,and 3 Bna P5CDHs were identified by using the genomic annotation information of‘Zhongshuang 11’.Phylogenetically,these gene families were divided into different evolutionary branches,and members of the same subgroups had similar physical and chemical properties,gene/protein structure,and conserved motifs.Evolutionary pressure analysis showed that these genes were subjected to strong purification selection.Cis-acting element analysis revealed that there were common and specific transcriptional regulatory mechanisms among the four kinds of gene families.In this study,rapeseed seedlings were respectively treated with salt stress,low potassium(K),low phosphate(P),and ammonium toxicity,and both shoots and roots were respectively sampled for transcriptomic analysis.The results indicated that the relative expression levels of genes related to proline synthesis were generally up-regulated under the above-mentioned four stresses,whereas the relative expression levels of genes regulating proline degradation were down-regulated under salt and low P stresses.Gene co-expression network analysis demonstrated that BnaC4.P5CS1a and BnaA5.P5CS1 might play central roles in the proline-mediated stress responsive networks in rapeseed.Through bioinformatics identification of proline metabolism gene family and analysis of transcription characteristics under various abiotic stresses,this study will provide a theoretical basis for further study of proline-mediated stress resistance,and will also provide excellent gene resources for genetic improvement of abiotic stress resistance mediated by proline metabolism in Brassica napus.