毛果杨nsLTP基因家族全基因组水平鉴定及其表达特性分析

Genome-wide Identification and Expression Analysis of nsLTP Gene Family in Populus trichocarpa

植物非特异性脂质转移蛋白(non-specific lipid transfer proteins,nsLTP)是一类多基因家族编码碱性蛋白,负责脂肪酸体外结和与膜之间的磷脂转移,在植物生长发育和逆境胁迫响应中扮演着重要角色。目前为止,尚无模式植物毛果杨(Populus trichocarpa)nsLTP家族的研究报导。本研究从全基因组水平对PtrnsLTP家族成员的基因数量、亲缘关系、基因结构、编码蛋白保守基序等特性进行了分析,结果表明:PtrnsLTP家族共由39个基因组成,进化成5个亚家族,其中A亚族含有6个基因、B亚族含有2个、C亚族含有13个、D亚族含有3个、E亚族含有15个。PtrnsLTP家族包含7对旁系同源基因,其中1对大于1,6对Ka/Ks均远小于1,且这6对基因均处于同一个大的进化分支上,进化压力的不同导致基因间的功能出现了分化,编码蛋白均含有Motif 1和Motif 2保守基序。利用qRT-PCR技术并结合杨树转录组数据对PtrnsLTP的组织表达与盐胁迫响应特性研究发现:各家族成员在毛果杨根、茎和叶中均有表达且经qRT-PCR技术验证后与网站预测结果基本吻合,有11、15和13个成员分别在根、茎和叶中有较高的表达,表明该基因家族参与了杨树不同组织的生长发育;NaCl胁迫下,该家族39个基因中分别有26个成员在根部、14个成员在叶部表达量随着胁迫时间的增加而升高,而32个基因在茎部表现为先升高后降低的趋势。本研究结果对于PtrnsLTP家族基因生物学功能的鉴定与盐胁迫响应基因资源的工作有着积极的推动作用。

Non-specific lipid transfer proteins(nsLTP),a polygene family of basic lipid transfer proteins,are responsible for the transfer of phospholipids between fatty acids and membrane in vitro,and play an important role in plant growth and development and the response to stress.There have been no reports on the nsLTP family of Populus trichocarpa.In this study,the number of genes,genetic relationship,gene structure and conserved motif of coding proteins of PtrnSLTP family members were analyzed at the genome-wide level.The results showed that the PtrnsLTP family was composed of 39 genes and evolved into five subfamilies,among which six genes in subfamily A,two genes in subfamily B,13 genes in subfamily C,three genes in subfamily D,and 15genes in subfamily E.PtrnsLTP family contained seven pairs of paragenetic homologous genes,among which one pair was greater than one,and the six pairs of Ka/Ks were all far less than one.Moreover,these six pairs of genes were all on the same large evolutionary branch,and different evolutionary pressures led to functional differentiation among genes.Both encoded proteins contained conserved motifs in Motif 1 and Motif 2.Using qRT-PCR technology combined with P.trichocarpa data to study the tissue expression of PtrnsLTP and the response characteristics of salt stress,it was found that all family members expressed in the roots,stems and leaves of P.trichocarpa.The results were basically consistent with the prediction results by the bioinformatics analysis of the website.There were 11,15 and 13 members respectively having higher expression in roots,stems and leaves,indicated that this gene family was involved in the growth and development of different tissues of P.trichocarpa.Under NaCl stress,among the 39 genes in the family,26 genes expressed in the root and 14genes expressed in the leaves increased with the increase of stress time,while 32 genes expressed in the stem first increased and then decreased.The results have a positive role in promoting the identification of the biological function of PtrnsLTP family genes and the work of salt stress response gene resources.