Abstract Sugar transporter proteins (STPs) play an important role in plant growth and development and stress resistance. Pepper (Capsicum annuum L.) is a significant economic crop and is widely cultivated worldwide. However, the evolution and the roles of STP genes in the growth and development and in coping with abiotic stresses in pepper are poorly known. Here, we characterized STP gene family in pepper through integration of chromosomal location, gene structure, conserved motif, phylogeny, expression patterns in different tissues and abiotic stresses. Using bioinformatics-based methods, we identified 17 putative STP genes in pepper. Chromosome mapping indicated that they are unevenly distributed on 9 chromosomes and there are tandem duplication events. Gene structure analysis revealed that intron numbers among these CaSTP genes ranged from 2 to 5, except that CaSTP12 and CaSTP13 genes contained no introns. The phylogenetic tree of STP genes from pepper and other plant species revealed that STP genes were grouped into 4 subfamilies, suggesting that these gene subfamilies may have diverged from a single common ancestor prior to the mono-dicot split. Gene expression analysis based on RNA-seq data showed that three genes were expressed constitutively in all the tissues analyzed, implying that these genes might have specific function in pepper. Stress data analysis showed that the expression profiles of some members of the CaSTP gene family were altered under cold, heat, salt and hormone stress conditions. The present results will provide valuable information into the evolutionary relationships and functional divergence of the STP family in the future.

中文翻译：

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辣椒中的糖转运蛋白：鉴定、表征、进化和表达模式

摘要 糖转运蛋白（STPs）在植物生长发育和抗逆性中发挥重要作用。胡椒 (Capsicum annuum L.) 是一种重要的经济作物，在世界范围内广泛种植。然而，STP 基因在辣椒生长发育和应对非生物胁迫中的进化和作用却鲜为人知。在这里，我们通过整合染色体位置、基因结构、保守基序、系统发育、不同组织中的表达模式和非生物胁迫来表征辣椒中的 STP 基因家族。使用基于生物信息学的方法，我们在辣椒中鉴定了 17 个假定的 STP 基因。染色体作图表明它们在9条染色体上分布不均，存在串联重复事件。基因结构分析表明，除了CaSTP12和CaSTP13基因不含内含子外，这些CaSTP基因中的内含子数量在2到5个之间。来自辣椒和其他植物物种的 STP 基因的系统发育树显示，STP 基因分为 4 个亚家族，这表明这些基因亚家族可能在单双子叶植物分裂之前从一个共同的祖先分化出来。基于 RNA-seq 数据的基因表达分析表明，在所有分析的组织中，三个基因组成型表达，这意味着这些基因可能在辣椒中具有特定功能。胁迫数据分析表明，在冷、热、盐和激素胁迫条件下，CaSTP 基因家族的一些成员的表达谱发生了改变。