高粱MCU蛋白家族基因鉴定及表达分析

Identification and Expression Analysis of MCU Protein Family Genes in Sorghum Bicolor

摘要: MCU是细胞Ca²⁺通道Uniporter复合物的重要组分，在胞质内Ca²⁺的信号转导以及细胞衰老途径都具有调控作用。但目前为止，植物中MCU家族的研究很少被报道。为阐明高粱中MCU蛋白的功能，本研究以生物信息为应用手段，筛选并鉴定出4个SbMCUs家族成员。通过染色体定位及同源性分析得出，SbMCUs家族成员分布在3条染色体上，且仅存在一对复制基因；并通过Ka/Ks分析可知SbMCUs家族基因的进化经受纯化选择压力。保守性分析得出，SbMCUs基因家族包含1个功能结构域，即Mitochondrial Calcium Uniporter (PF04678)；10个保守结构域和2个跨膜结构域。系统进化树分析将SbMCUs家族分为2个亚组，Subgroup I和Subgroup II。表达模式分析可知，SbMCUs基因家族在不同组织器官和生长发育阶段的表达量不同，其中SbMCU5.2的表达量最高。ABA、PEG (渗透胁迫)和干旱表达谱芯片数据分析发现，Subgroup II中SbMCU5.1对ABA、PEG和干旱胁迫均有明显响应，且在干旱胁迫时，Sensitive Genotype的表达量上调最高(Log2变化倍数=5.41)，但SbMCU5.1启动子中响应的相关元件并不多。本研究结果为MCU基因家族提供了新的研究方向，并为后续研究提供了重要依据。

Abstract: MCU is an important part of Ca²⁺channel uniporter complex. It plays a regulatory role in intracel-lular Ca²⁺ signal transduction and cell aging pathway. However, up to now, few studies were re-ported about the MCU gene family in plant. Hence, we used bioinformatic method to screen MCU family genes in sorghum genome, and identified a total of 4 SbMCU genes. Chromosomal location and synteny analysis revealed that 4 SbMCUs located on 3 chromosomes, and possessed 1 gene duplication events. Analysis of the Ka (non-synonymous substitution rate)/Ks (synonymous subs-titution rate) ratios suggested that the duplication of SbMCU genes mainly underwent purifying selection. We also suggested that SbMCUs family protein sequences were highly conserved, in-cluding three conserved functional domains (Mitochondrial calcium uniporter, PF04678), 10 con-served motifs and at 2 transmenbrane domains. Furthermore, we further constructed a phyloge-netic tree, and found that they were clustered into two subgroups. Expression patterns analysis indicated that SbMCUs family genes were differentially expressed in various tissues, and the ex-pression of SbMCU5.2 was the highest. Expression profile chips of ABA, PEG (osmotic stress) and drought stresses analysis found that SbMCU5.1 of subgroup II was significantly responsive to ABA, PEG and drought stresses. After drought treatment, the expression of SbMCU5.1 in sensitive geno-type was the highest up-regulated (log2 fold change = 5.41), but there were few components asso-ciated with the response in the SbMCU5.1 promoter. These results could provide new valuable in-formation and will facilitate further research.