丝瓜POD基因家族鉴定及盐胁迫下表达分析

Genome-wide Identification of the POD Gene Family and Expression Analysis Under Salt Stress in Luffa(Luffa acutangula)

过氧化物酶(peroxidase,POD)是植物体内普遍存在且活性较高的一种酶,在植物生长发育和胁迫响应中发挥重要作用。从丝瓜基因组层面分析POD家族基因及其对盐胁迫响应的研究鲜有报道。本研究利用生物信息学方法在丝瓜基因组中鉴定出94个POD家族成员,具有相似的基因结构,大多数含有3个或者4个外显子;编码氨基酸数量在89~688之间,平均为309个;理论等电点(pI)介于4.58~10.34之间;其中57个成员为碱性氨基酸,82个成员为亲水性蛋白;POD家族成员不均匀地分布在丝瓜13条染色体上,其中7号染色体最多(20个),12号最少(1个)。系统发育分析将丝瓜POD家族划分为8个亚家族。与拟南芥的POD家族基因共线性分析表明,2个物种之间有12对共线性基因,丝瓜中POD家族基因发生了扩张。蛋白保守结构域分析表明,丝瓜POD家族成员都含有plant peroxidases保守结构域和相似的保守基序。启动子区域的顺式作用元件分析发现,启动子中含有大量的脱落酸、赤霉素、生长素、乙烯、水杨酸、茉莉酸甲酯等植物激素响应元件和低温、低氧、光、干旱、防御和胁迫响应等胁迫响应顺式元件。丝瓜幼苗受到200、500 mmol/L NaCl胁迫处理时,POD活性增强,56个POD家族成员基因表达量显著上升。通过表达趋势分析,获得2个显著富集趋势,包含的35个基因在不同浓度盐胁迫处理下显著上调表达,表明这些基因可能参与丝瓜对盐胁迫响应。本研究从基因组层面鉴定丝瓜POD家族成员,并进行其理化性质分析及盐胁迫下表达分析,为更深入研究丝瓜POD基因家族的生物学功能奠定基础。

Peroxidase(POD)is a ubiquitous and highly active enzyme in plants,which plays an important role in plant growth and development and stress response.There are few reports on the analysis of POD family genes and the response to salt stress.In this study,94 POD family members were identified in luffa genome by bioinformatics methods.They had similar gene structure,most of them contained 3-4 exons.The number of coding amino acids were ranged from 89 to 688,with an average of 309.The pI of the protein was between 4.58 and 10.34.57 of them were basic amino acids.82 members were hy-drophilic proteins.POD family members were unevenly distributed on 13 chromosomes of luffa,of which chromosome 7 was the most(20)and chromosome 12 was the least(1).Phylogenetic analysis divided the POD family members into 8 subfami-lies.The analysis of the collinearity of POD family genes with Arabidopsis showed that there were 12 pairs of collinearity genes between the two species,and the POD family genes in luffa had expanded.Protein conserved domain analysis showed that POD family members all contained plant peroxidases conserved domains and had similar conserved bases.The gene promoter contained a large number of plant hormone response elements such as abscisic acid,gibberellin,auxin,ethylene,salicylic acid,methyl jasmonate,and stress response cis elements such as low temperature,hypoxia,light,drought defense and stress response,indicating that it may be induced by abiotic stress.The analysis of cis acting elements in the promoter showed that the promoter contained a large number of phytohormone(abscisic acid,gibberellin,auxin,ethylene,salicylic acid,methyl jasmonate)response elements and stress(low temperature,low oxygen,light,drought,defense and stress response)response cis elements.When luffa seedlings were stressed by 200 and 500 mmol/L NaCl,the POD activity increased,and the gene expression of 56 POD family members increased significantly.Through expression trend analysis,two significant en-richment trends were obtained,including 35 genes that were significantly up-regulated under salt stress,indicating that the genes may participate in the response to salt stress.This study is the first time to identify the members of the POD family of luffa at the genomic level,and analyzed the physical properties and expression under salt stress.The results of this study would lay a theoretical foundation for exploring the biological functions of POD family members in luffa.