Abstract The SQUAMOSA promoter binding protein (SBP)-box consists of a family of transcription factors unique to plants and mediates important roles in plant growth and development. We identified 57 SBP genes in the Brassica juncea (swollen-stem mustard) genome, and analyzed the structural characteristics, evolutionary relationships, as well as their involvement in regulation and response to environmental stress. By the help of phylogenetic analysis, the SBP genes were divided into seven subgroups (G1-G7). Interestingly, most members of the same group shared conserved gene structure and motifs as well as gene duplications. This suggests that their functions are redundant highlighting evolutionary relatedness. Identification of the cis-acting elements of the promoter revealed multiple regulatory elements that responded to phytohormone or abiotic stresses. In addition, data from GO annotation indicated that BjuSBPs play a role in biological processes. Further interrogation of the expression of BjuSBPs in different stages of swollen-stem mustard showed spatiotemporal expression patterns. On the other hand, quantitative real-time polymerase chain reaction (qRT-PCR) showed that the expression levels of SBP genes at the development stage correlated with their transcriptome data but treatment with phytohormones affected their expression levels. Our study showed that the SBP-box responds to phytohormone signals and the genes might confer different functions in the development of the mustard plant. Our data lay the foundation for further studies evaluating the regulatory mechanisms of SBP-box family of genes.

中文翻译：

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芥菜生长发育中SBP-box家族进化和基因表达分析的新见解

摘要 SQUAMOSA 启动子结合蛋白 (SBP)-box 由植物特有的转录因子家族组成，在植物生长发育中发挥重要作用。我们在芥菜（肿胀茎芥）基因组中鉴定了 57 个 SBP 基因，并分析了它们的结构特征、进化关系以及它们在调节和对环境压力的反应中的参与。通过系统发育分析，将SBP基因分为7个亚组（G1-G7）。有趣的是，同一组的大多数成员共享保守的基因结构和基序以及基因重复。这表明它们的功能是多余的，突出了进化相关性。启动子的顺式作用元件的鉴定揭示了响应植物激素或非生物胁迫的多个调节元件。此外，来自 GO 注释的数据表明 BjuSBPs 在生物过程中发挥作用。进一步询问 BjuSBPs 在肿胀茎芥菜不同阶段的表达显示出时空表达模式。另一方面，定量实时聚合酶链反应 (qRT-PCR) 表明，SBP 基因在发育阶段的表达水平与其转录组数据相关，但植物激素处理会影响其表达水平。我们的研究表明 SBP-box 对植物激素信号有反应，这些基因可能在芥菜植物的发育中赋予不同的功能。