向日葵DGATs基因家族的鉴定及表达分析

Genome-wide identification and relative expression analysis of DGATs gene family in sunflower

二酰基甘油酰基转移酶(Diacylglycerol acyltransferase,DGAT)在植物油脂代谢和抗逆过程中发挥重要作用。为探究DGAT基因在向日葵(Helianthus annuus L.)中的进化及在油脂积累和非生物胁迫应答中的功能,本研究以拟南芥AtDGATs基因为基础序列,通过同源比对从向日葵基因组中获得18个DGAT同源基因序列,并对其染色体分布、基因结构、蛋白保守结构域、系统进化关系、组织特异性表达以及非生物胁迫下的表达模式进行系统分析。结果表明,向日葵DGATs基因可分为4个亚族(DGAT1、DGAT2、DGAT3和WSD),且同一亚族成员具有相似的基因结构和蛋白保守基序;HaDGATs基因的启动子区富含逆境和植物激素响应相关元件;片段复制是导致该基因家族扩张的主要因素;qRT-PCR结果表明,HaDGAT1、HaDGAT2和HaDGAT3主要在种子发育的早、中期表达,与种子油脂快速积累密切相关,而HaWSDs亚家族基因主要在茎、叶和花中表达。盐、低温、干旱和ABA处理后,多数HaWSDs基因在向日葵根、茎和叶中呈现诱导表达,推测其可能在对逆境胁迫的响应中起重要作用。这些结果为进一步研究向日葵DGATs基因的功能奠定了基础。

Diacylglycerol acyltransferase(DGAT)plays an important role in plant oil metabolism and stress resistance.To explore the evolution of DGAT gene in sunflower(Helianthus annuus L.)and its function in oil biosynthesis and response to abiotic stresses,18 homologous gene sequences of DGAT were obtained from the sunflower genome database by alignment with Arabidopsis thaliana AtDGATs genes.Then,chromosome distribution,gene structure,conserved protein motifs,phylogenetic relationship,tissue-specific expression of HaDGATs,and their expressing patterns under abiotic stresses were systematically investigated.The results showed that sunflower DGATs genes were divided into four subfamilies(DGAT1,DGAT2,DGAT3,and WSD),and the members of the same subfamily shared similar gene structures and conserved motifs.The promoter regions of HaDGATs harbored multiple cis-elements related to environmental stresses and plant hormone response.The main factor for HaDGATs amplification was fragment duplication.The qRT-PCR indicated that HaDGAT1,HaDGAT2,and HaDGAT3 were mainly expressed in the early and middle stages of sunflower seed development,which coincided with the rapid accumulation period of oil in seeds,while HaWSD subfamily genes were mainly expressed in stems,leaves,and petals.Most of HaWSD genes could be induced by NaCl,low temperature,drought,and ABA treatments in sunflower roots,stems,and leaves,indicating that they might play essential roles in dealing with various abiotic stresses.The results revealed that HaDGATs had functional differentiation in regulating lipid biosynthesis and abiotic stresses.This study provides an important foundation for further understanding the function of sunflower DGAT genes.