Identification of AP2/ERF Transcription Factor Family Genes and Expression Patterns in Response to Drought Stress in Pinus massoniana

Pinus massoniana Lamb. is found in 17 Chinese provinces and is an important timber tree species in southern China. The current seasonal drought climate is becoming increasingly severe, threatening P. massoniana growth and limiting the development of the P. massoniana industry. Plant growth, development, and stress were all regulated by AP2/ERF. We identified 124 AP2/ERF transcription factor family members in this study and discovered that all the genes had their own conserved structural domains and that PmAP2/ERFs were divided into 12 subfamilies with high conservation and similarity in gene structure and evolutionary level. Nine PmAP2/ERF genes were constitutively expressed under drought treatment, and it was hypothesized that the PmAP2/ERF96 gene negatively regulated drought stress, PmAP2/ERF46 and PmAP2/ERF49 genes showed a positive or negative response to drought in different tissues, while the remaining six genes were positively regulated. The PmAP2/ERF genes responded to drought stress following treatment with the exogenous hormones SA, ABA, and MeJA, but the expression patterns differed, with each gene responding to at least one exogenous hormone to induce up-regulation of expression under drought stress, with PmAP2/ERF11, PmAP2/ERF44, PmAP2/ERF77, and PmAP2/ERF80 genes significantly induced by three hormones. The genes mentioned above may be involved in hormone signaling pathways in response to drought stress. The results indicate that the PmAP2/ERF genes may positively or negatively regulate the corresponding signaling pathways in P. massoniana to improve drought resistance.