甘蔗割手密BAG基因家族的鉴定与表达分析

Identification and Expression Analysis of BAG Gene Family in Sugarcane Saccharum spontaneum

BAG(Bcl-2 associated athanogene)在真核生物中是一种保守的辅助伴侣蛋白。本研究在甘蔗割手密(Saccharum spon-taneum)基因组中鉴定获得24个BAG基因,分布在19条染色体上,根据其系统发育关系可分为3个组。研究发现,全基因组复制或片段复制是该家族的主要扩张方式。顺式作用元件预测分析表明,SsBAGs主要参与植物激素调节、非生物胁迫响应、光响应和植物生长发育等。转录表达谱分析表明,多数SsBAGs在茎中的表达量显著高于叶片中的,而在叶片的库源过渡区域的表达高于叶片其他区域的。此外,不同SsBAGs在干旱胁迫下的表达存在差异。亚细胞定位表明,ScBAG1a和ScBAG2a均定位于细胞质和细胞核,与生物信息学分析结果一致。值得指出的是,BAG蛋白的结构域和BAG基因的表达模式在甘蔗和水稻(Oryza sativa)中均相当保守。甘蔗BAG基因家族扩张所造成的家族成员功能冗余在一定程度上可能与甘蔗作为多年生作物的抗逆性、抗病性和再生性有关。本研究初步揭示了SsBAG基因在甘蔗割手密中的生长发育和逆境胁迫响应中发挥的功能,为进一步研究其作用机制奠定了基础。

BAG(Bcl-2 associated athanogene) is a conserved co-chaperone protein in eukaryotes. In this study, 24 BAG genes were identified in sugarcane Saccharum spontaneum genome, which were distributed on 19 chromosomes and could be divided into three groups according to their phylogenetic relationships. It was found that whole genome duplication or segmental duplication was the main expansion mode of this family. The prediction analysis of cis regulatory element showed that SsBAGs were mainly involved in plant hormone regulation, abiotic stress response, light response, growth and development of plant and so on. Transcriptional expression profile analysis showed the most of SsBAGs were expressed in stems, much significantly higher than in leaves, and the expression of SsBAGs in sink-source transition region of leaves was higher than in the other regions of leaves. In addition, the different members of SsBAGs family had distinct patterns of expression under drought stress. Subcellular localization analysis showed that both ScBAG1a and ScBAG2a were localized in cytoplasm and nucleus, which was consistent with the results of bioinformatics prediction. It is noteworthy that the domains of BAG protein and the expression pattern of BAG genes are highly conserved in both sugarcane and rice(Oryza sativa). The functional redundancy of family members caused by the expansion of BAG gene family may be related to the stress resistance, disease resistance and regeneration of sugarcane as a perennial crop. These results proposed the roles of SsBAGs in the plant growth and develop-ment and stress response of sugarcane Saccharum spontaneum, which laid a foundation for further revealing their molecular function in sugarcane.