巴西橡胶树GRAS基因家族鉴定及表达分析

Genome-wide Identification and Expression Analysis of GRAS Gene Family in Hevea brasiliensis

GRAS是植物特有的转录因子,在植物生长发育过程以及非生物胁迫应答中具有重要的调控作用,然而在巴西橡胶树(Hevea brasiliensis)中还未见关于该基因家族的报道。本研究利用生物信息学工具分析巴西橡胶树GRAS基因家族成员的蛋白质理化性质、系统进化关系、基因结构、染色体位置及启动子顺式作用元件,利用转录组数据及实时荧光定量PCR(qPCR)分析橡胶树GRAS基因的表达模式。结果表明:在巴西橡胶树基因组中共鉴定到91个GRAS家族成员,分别命名为HbGRAS1~HbGRAS91,其分子量在14.07~89.46 kDa之间。亚细胞定位预测结果显示,HbGRAS蛋白主要定位于细胞核和叶绿体。系统发育分析将其划分为14个亚家族,同一亚族成员的基因结构和基序组成较为保守。橡胶树GRAS基因分布在除11号染色体外的其他17条染色体和2条Scaffold上,其中17个HbGRAS基因组成10个串联重复事件。共线性分析显示,片段重复区域中有87个HbGRAS基因,说明片段重复可能是橡胶树GRAS基因扩张的主要驱动力。启动子顺式作用元件分析显示,橡胶树GRAS家族包含多个植物激素和胁迫应答顺式作用元件。HbGRAS基因表达具有组织特异性,并与橡胶树叶片发育有关。GRAS亚家族成员DELLA基因的表达与橡胶树木质部发育有关并受赤霉素(gibberellin,GA)抑制。本研究结果为橡胶树GRAS基因的功能研究提供参考。

GRAS is a plant-specific transcription factor,which plays an important regulatory role in plant growth and development,and abiotic stress response.GRAS gene family has not been reported in Hevea brasiliensis.In this study,bioinformatics tools were used to analyze the physicochemical properties,phylogenetic relationships,gene structures,chromosome positions,and cis-acting elements of promoters of GRAS gene family members in H.brasiliensis.The expression patterns of HbGRAS were analyzed by transcriptome data and real-time quantitative PCR(qPCR).A total of 91 GRAS family members were identified from H.brasiliensis genome,named HbGRAS1–HbGRAS91,with molecular weights ranging from 14.07–89.46 kDa.The results of subcellular localization prediction showed that HbGRAS was mainly localized in the nucleus and chloroplast.Those proteins were divided into 14 subfamilies based on phylogenetic analysis.The gene structures and motif compositions within the same subfamily were relatively conserved.The 91 GRAS family members were distributed in 17 chromosomes and two scaffolds except for chromosome 11 in rubber tree.We found that 17 HbGRAS genes were involved in 10 tandem repeat events.Collinearity analysis revealed the segmental duplication regions containing 87 HbGRAS genes,suggested that gene fragment duplication may be the major driver of GRAS gene expansion in H.brasiliensis.Cis-acting element prediction showed that HbGRAS family contained multiple phytohormone and stress-responsive elements.The expression patterns of HbGRAS genes had tissue specificity and were associated with leaf development.The expressions of DELLA genes,a member of the GRAS subfamily,were related to the xylem development and were repressed by gibberellin(GA).Those results provide a reference for functional research on the GRAS genes in rubber trees.