毛果杨类胡萝卜素裂解双加氧酶基因家族全基因组水平鉴定及其干旱与盐胁迫响应分析

Genome-wide Identification and Expressional Analysis of Carotenoid Cleavage Dioxygenases(CCD)Gene Family in Populus trichocarpa under Drought and Salt Stress

CCD基因编码的类胡萝卜素裂解双加氧酶催化胡萝卜素共轭双键裂解形成脱辅基类胡萝卜素及其衍生物,研究表明CCD基因在植物生长发育与逆境胁迫响应中发挥着重要作用。然而,目前尚无木本模式植物毛果杨(Populus trichocarpa)PtrCCD的研究报导,本研究发现其在盐胁迫和干旱胁迫下的表达量存在明显差异,据此拟从分子水平上揭示该基因家族成员功能。本研究从全基因组水平对毛果杨PtrCCD基因家族成员数量、进化关系、染色体位置、基因结构、编码蛋白基本特征和启动子顺式作用元件等特征进行了分析。结果表明:PtrCCD家族由11个基因组成,可分为CCD4和CCD8两个亚族,分别包括9个和2个基因;PtrCCD家族存在5对Ka/Ks均远小于1的旁系同源基因;PtrCCD家族编码蛋白均含有5个共有保守结构域Motif 1、Motif 2、Motif 3、Motif 9和Motif 11,且处于同一进化分支的基因编码蛋白序列高度保守;PtrCCD家族基因启动子区含有大量非生物胁迫和激素响应元件,其中PtrCCD8a启动子含有5种类型、16个元件。PtrCCD家族基因表达特性分析表明:PtrCCD家族基因在根、茎和叶中表达量存在明显差异,并且多数成员在茎部表达量要高于其他2个部位;干旱胁迫不同时间下,处于同一进化分支的基因表达模式基本相同,不同分枝的基因表达量存在明显差异;NaCl胁迫不同时间下,PtrCCD家族各基因在根、茎和叶中表达量不同、但均表现出先上升后下降再上升的变化趋势,处于同一进化分支的基因表达模式基本相同。PtrCCD家族基因在干旱和盐胁迫情况下具有不同程度的响应能力,进一步表明该基因家族在非生物胁迫中具有重要作用。

Carotenoid cleavage dioxygenases(CCD)specifically catalyzed the cleavage of conjugated double bonds of carotenoids to form various apocarotenoids and their derivatives,which played various important roles in plant growth and development and stress response.However,no research has been reported on PtrCCD in the woody model plant Populus trichocarpa.This study found that its expression level was significantly different under salt stress and drought stress.Based on this,it was planned to reveal the function of PtrCCD family at the molecular level..The number of PtrCCD family members,evolutionary relationship,chromosome location,gene structure,basic characteristics of the encoded protein,promoter cis-acting elements,and response to drought and salt stress of PtrCCD gene family were analyzed at genome-level of P.trichocarpa,respectively.The results demonstrated that the PtrCCD family could be divided into two sub-families,CCD4 and CCD8,which included 9 and 2 genes,respectively.There were 5 pairs of paralogous genes,with Ka/Ks far less than 1.All proteins encoded by the PtrCCD family contained 5 common Motifs,such as Motif 1,Motif 2,Motif 3,Motif 9,and Motif 11.The promoter regions of PtrCCD gene family contained a large number of abiotic stress and hormone response cis-elements,among which the PtrCCD8a promoter contained 5 types and 16 elements.Analysis of the expression characteristics of the PtrCCD family showed that the PtrCCD family genes exhibited tissue-specified expression patterns and mainly expressed in stems compared with in roots and leaves,respectively.Moreover,there were significant differences of expression levels of PtrCCD family genes among roots,stems,and leaves of poplar in response to drought and salt stress during different times.The PtrCCD gene family had different response to drought and salt stress,which further indicated that this gene family played an important role in abiotic stress.