Identification and Characterization of EIN3/EIL Transcription Factor Family Members in Pinus massoniana Lamb.

Transcription factors refer to types of proteins that perform significant functions in the process of gene expression regulation. The ethylene insensitive 3/ethylene insensitive 3-like (<i>EIN3/EIL</i>) family, functioning as significant transcription factors regulating ethylene, plays a critical role in the growth and development of plants and participates in the plant's response to diverse environmental stresses. <i>Pinus massoniana</i> is an excellent native tree with high economic and ecological value. However, the study of <i>EIN3/EIL</i> genes in gymnosperms, for instance, <i>P. massoniana,</i> is still relatively limited. In this research, four putative <i>EIN3/EIL</i> genes were identified in the transcriptome of <i>P. massoniana</i>. Bioinformatics analysis showed that <i>PmEIL</i> genes contain a highly conserved EIN3 domain and other structural features of acidic, proline-rich and glutamine-rich sites. The molecular evolution tree analysis demonstrated that the <i>EIN3/EIL</i> family was partitioned into three categories (A, B, and C), and the number, type, and distribution of conserved motifs grouped in one category were similar. The results of qRT-PCR indicated that the expression levels of <i>PmEIL</i> genes were markedly elevated in needles compared to other tissues. Through the analysis of expression patterns of the <i>PmEIL</i> genes under various stress treatments, it was found that the <i>PmEIL</i> genes could participate in plant hormone stimulation induction, osmosis, drought and other response processes. In addition, PmEIL is a nuclear localization protein. PmEIL1, PmEIL3, and PmEIL4 are transcriptional activators, while PmEIL2 is a transcriptional suppressor. This research provides a basis for further elucidating the function of EIN3/EIL transcription factors in growth, development and stress response of <i>P. massoniana</i>.