Table_3_Genome-wide identification and expression analysis of the U-box E3 ubiquitin ligase gene family related to salt tolerance in sorghum (Sorghum bicolor L.).xlsx

Plant U-box (PUB) E3 ubiquitin ligases play essential roles in many biological processes and stress responses, but little is known about their functions in sorghum (Sorghum bicolor L.). In the present study, 59 SbPUB genes were identified in the sorghum genome. Based on the phylogenetic analysis, the 59 SbPUB genes were clustered into five groups, which were also supported by the conserved motifs and structures of these genes. SbPUB genes were found to be unevenly distributed on the 10 chromosomes of sorghum. Most PUB genes (16) were found on chromosome 4, but there were no PUB genes on chromosome 5. Analysis of cis-acting elements showed that SbPUB genes were involved in many important biological processes, particularly in response to salt stress. From proteomic and transcriptomic data, we found that several SbPUB genes had diverse expressions under different salt treatments. To verify the expression of SbPUBs, qRT-PCR analyses also were conducted under salt stress, and the result was consistent with the expression analysis. Furthermore, 12 SbPUB genes were found to contain MYB-related elements, which are important regulators of flavonoid biosynthesis. These results, which were consistent with our previous multi-omics analysis of sorghum salt stress, laid a solid foundation for further mechanistic study of salt tolerance in sorghum. Our study showed that PUB genes play a crucial role in regulating salt stress, and might serve as promising targets for the breeding of salt-tolerant sorghum in the future.

植物U-box（PUB）型E3泛素连接酶在众多生物学过程及胁迫应答中发挥关键作用，但目前对于其在高粱（Sorghum bicolor L.）中的功能尚不清楚。本研究从高粱基因组中鉴定得到59个SbPUB基因。基于系统发育分析，这59个SbPUB基因可被划分为5个类群，该分类结果亦得到这些基因保守基序与基因结构的支持。研究发现SbPUB基因在高粱的10条染色体上分布不均，其中第4号染色体上的PUB基因数量最多，达16个，而第5号染色体上未检测到PUB基因。顺式作用元件（cis-acting elements）分析结果显示，SbPUB基因参与诸多重要生物学过程，尤其参与盐胁迫应答。从蛋白质组学与转录组学数据中，我们发现多个SbPUB基因在不同盐胁迫处理下呈现出多样化的表达模式。为验证SbPUB基因的表达情况，本研究还在盐胁迫条件下开展了实时定量逆转录聚合酶链反应（qRT-PCR）分析，所得结果与表达谱分析结果一致。此外，本研究发现12个SbPUB基因含有MYB相关顺式作用元件，而MYB类元件是黄酮类生物合成的重要调控因子。上述研究结果与我们此前开展的高粱盐胁迫多组学分析结果一致，为后续开展高粱耐盐性的分子机制研究奠定了坚实基础。本研究表明，PUB基因在盐胁迫调控中发挥关键作用，有望成为未来培育耐盐高粱品种的潜在靶标。