Table_5.docx

The SQUAMOSA promoter binding protein (SBP)-box proteins are plant-specific transcriptional factors in plants. SBP TFs are known to play important functions in a diverse development process and also related in the process of evolutionary novelties. SBP gene family has been characterized in several plant species, but little is known about molecular evolution, functional divergence and comprehensive study of SBP gene family in Rosacea. We carried out genome-wide investigations and identified 14, 32, 17, and 17 SBP genes from four Rosacea species (Fragaria vesca, Pyrus bretschneideri, Prunus persica and Prunus mume, respectively). According to phylogenetic analysis arranged the SBP protein sequences in seven groups. Localization of SBP genes presented an uneven distribution on corresponding chromosomes of Rosacea species. Our analyses designated that the SBP genes duplication events (segmental and tandem) and divergence. In addition, due to highly conserved structure pattern of SBP genes, recommended that highly conserved region of microsyneteny in the Rosacea species. Type I and II functional divergence was detected among various amino acids in SBP proteins, while there was no positive selection according to substitutional model analysis using PMAL software. These results recommended that the purifying selection might be leading force during the evolution process and dominate conservation of SBP genes in Rosacea species according to environmental selection pressure analysis. Our results will provide basic understanding and foundation for future research insights on the evolution of the SBP genes in Rosacea.

SQUAMOSA启动子结合蛋白框（SBP-box）蛋白是植物特有的转录因子。已知SBP转录因子在多种植物发育进程中发挥重要功能，同时也与进化新性状的形成过程相关。目前已有多个植物物种中的SBP基因家族得到系统鉴定，但关于蔷薇科（Rosaceae）植物SBP基因家族的分子进化、功能分化以及全面研究仍相对匮乏。本研究通过全基因组范围的分析，从4种蔷薇科植物（分别为森林草莓Fragaria vesca、白梨Pyrus bretschneideri、桃Prunus persica以及梅Prunus mume）中分别鉴定得到14、32、17和17个SBP基因。基于系统发育分析，将SBP蛋白序列划分为7个进化组。SBP基因在对应蔷薇科物种的染色体上呈现不均匀分布的特征。本研究分析表明，SBP基因存在复制事件（包括片段复制和串联复制）并发生了分化。此外，由于SBP基因的结构模式高度保守，本研究推测蔷薇科植物中存在高度保守的微共线性区域。在SBP蛋白的不同氨基酸位点中检测到了I型和II型功能分化，但通过PMAL软件进行的替换模型分析显示未存在正向选择。结合环境选择压力分析，本研究结果表明，纯化选择可能是蔷薇科植物SBP基因进化过程中的主导驱动力，并维持了该基因家族的保守性。本研究结果将为未来蔷薇科植物SBP基因家族进化的相关研究提供基础认知与理论依据。