Genome-wide analysis of C2H2.2 gene family in Populus Trichocarpa and the function exploration of PtrC2H2.2-6 in osmotic stress.

C2H2 transcription factors are essential for increasing a plant's ability to withstand extreme conditions. However, research on the functions of C2H2 transcription factors in woody plants, particularly their responses to osmotic stress, is limited. This research identified 109 C2H2 genes, and the PtrC2H2.2 subfamily, which contains 28 genes, captured our keen interest, prompting an extensive molecular characterization. Evolutionarily, PtrC2H2.2 s have undergone 30 fragment duplications and 2 tandem duplications. PtrC2H2.2-6 acts as a core transcription factor, whose expression was decreased after both ABA and drought treatments, implying it may play a negative regulatory role in the osmotic stress response by regulating the expression of targets. Specifically, the PtrC2H2.2-6-RNAi poplar showed improved osmotic stress tolerance compared to the overexpressing line, which was more sensitive, and transcriptome data analyses flanked the molecular mechanisms of their possible regulation. In this research, we dissected the molecular features of the PtrC2H2.2 subfamily genes and elucidated the role of a specific member, the PtrC2H2.2-6 gene, in the ability of poplar to respond to osmotic stress. This discovery not only establishes a foundation for further exploration of its biological functions but also presents precious genetic assets for the development of drought-tolerant forest tree varieties through genetic engineering.