本氏烟NbGSLs基因家族鉴定与NbGSL2基因克隆

Genome-Wide Identification of the NbGSLs Gene Family and Cloning of NbGSL2 Gene in Nicotiana benthamiana

摘要: 胼胝质合酶(CalS)，即葡聚糖合酶样蛋白(GSL)，是调控植物胼胝质合成的关键酶，参与生长发育及逆境响应过程。本研究通过生物信息学方法系统鉴定了本氏烟NbGSLs基因家族，并对其染色体定位、蛋白理化特性、基因结构、保守结构域、系统发育关系、共线性及顺式作用元件进行全面分析。结果显示：1) 基因组中共鉴定12个NbGSLs成员，编码蛋白(1741~2136 aa)相对分子质量为202.72~243.90 kD，理论等电点8.31~9.23，均为碱性蛋白；2) 亚细胞定位预测显示，所有成员定位于胞间连丝；3) 基因结构分析表明，除NbGSL1外均含内含子，且普遍具有β-1,3-葡聚糖合酶和FKS1结构域；4) 共线性分析揭示家族内存在2个串联重复和6个片段重复事件，并与拟南芥AtGSLs家族形成3个共线性对；5) 启动子区含多种逆境响应元件，提示NbGSLs可能参与植物抗逆调控。基于表达预测筛选获得NbGSL2基因，成功克隆其5727 bp编码区，该基因编码1908个氨基酸，具有典型的跨膜结构和丰富的α-螺旋。本研究首次系统鉴定本氏烟NbGSLs基因家族并成功克隆NbGSL2，为解析其在韧皮部特异性表达及生物学功能奠定理论基础。

Abstract: Callose Synthases (CalS), also known as Glucan Synthase-Like proteins (GSL), are pivotal enzymes regulating callose deposition during plant development and stress responses. This study systematically identified the NbGSLs gene family in Nicotiana benthamiana through bioinformatics approaches, with comprehensive analyses of chromosomal distribution, protein physicochemical properties, gene structure, conserved domains, phylogenetic relationships, collinearity, and cis-acting elements. Key findings include: 1) Twelve NbGSLs members were identified, encoding alkaline proteins (1741~2136 aa) with molecular weights of 202.72~243.90 kD and theoretical pI values of 8.31~9.23; 2) Subcellular localization predictions indicated plasmodesmata targeting for all members; 3) Structural analysis revealed intron-containing genes (except NbGSL1) harboring conserved β-1,3-glucan synthase and FKS1 domains; 4) Collinearity analysis identified 2 tandem and 6 segmental duplication events within the family, with 3 orthologous pairs detected between NbGSLs and Arabidopsis AtGSLs; 5) Promoter regions contained multiple stress-responsive elements, suggesting NbGSLs’ potential roles in abiotic stress adaptation. NbGSL2, predicted to exhibit phloem-specific expression, was successfully cloned with a 5727-bp coding sequence encoding a 1908-amino-acid transmembrane protein rich in α-helices. This study is the first one to systematically identify the NbGSLs gene family in N. benthamiana and successfully clone NbGSL2, which lays a theoretical foundation for analyzing its specific expression and biological function in the phloem.