Table_1_Genome-wide identification of the auxin response factor (ARF) gene family in Magnolia sieboldii and functional analysis of MsARF5.docx

Auxin plays an essential role in flowering, embryonic development, seed dormancy, and germination. Auxin response factors (ARFs) are plant-specific key transcriptional factors in mediating the gene expression network of auxin signaling. Although ARFs in model plants such as Arabidopsis had been well characterized, their identities and potential roles in non-model plants are less studied. Here, we performed genome-wide identification of ARFs in Magnolia sieboldii K. Koch, a primitive species with high taxonomic importance and medicinal values. We found 25 ARF genes in M. sieboldii, which were widely distributed across multiple chromosomes. Based on sequence similarity, the encoded proteins could be either transcriptional repressors or activators. Gene expression analysis showed a dynamic pattern for many ARFs including MsARF5 during seed germination. In addition, overexpressing of MsARF5 showed that it restores many developmental defects in the Arabidopsis mutant. Moreover, two phenotypically distinct transgenic Arabidopsis lines were obtained, indicating a link between gene expression levels and developmental phenotypes. Taken together, we provided a systematic investigation of the ARF gene family in M. sieboldii and revealed an important role of MsARF5 in mediating auxin signaling.

生长素（Auxin）在植物开花、胚胎发育、种子休眠与萌发过程中发挥不可或缺的调控作用。生长素响应因子（Auxin response factors, ARFs）是植物特异性的关键转录因子，可介导生长素信号通路的基因表达网络。尽管模式植物拟南芥（Arabidopsis）中的ARFs已得到充分解析，但非模式植物中ARFs的身份与潜在功能仍研究相对匮乏。本研究针对兼具较高分类学重要性与药用价值的原始物种天女木兰（Magnolia sieboldii K. Koch），开展了ARF基因家族的全基因组鉴定。研究共在天女木兰中鉴定得到25个ARF基因，这些基因广泛分布于多条染色体上。基于序列相似性，其编码的蛋白可分为转录抑制因子与转录激活因子两类。基因表达分析显示，包括MsARF5在内的多数ARF基因在种子萌发过程中呈现动态表达模式。此外，过表达MsARF5可恢复拟南芥突变体的诸多发育缺陷。本研究还获得了两种表型差异显著的转基因拟南芥株系，表明基因表达水平与发育表型之间存在直接关联。综上，本研究对天女木兰的ARF基因家族开展了系统性研究，并揭示了MsARF5在介导生长素信号通路中的重要功能。