PtrVCS2 Regulates Drought Resistance by Changing Vessel Morphology and Stomatal Closure in Populus trichocarpa .

Drought has severe effects on plant growth, forest productivity, and survival throughout the world. Understanding the molecular regulation of drought resistance in forest trees can enable effective strategic engineering of novel drought-resistant genotypes of tree species. In this study, we identified a gene, , encoding a zinc finger (ZF) protein of the ZF-homeodomain transcription factor in (Black Cottonwood) Torr. & A. Gray. ex Hook. Overexpression of () in resulted in reduced growth, a higher proportion of smaller stem vessels, and strong drought-resistance phenotypes. Stomatal movement experiments revealed that the transgenics showed lower stomata apertures than wild-type plants under drought conditions. RNA-seq analysis of the transgenics showed that regulates the expression of multiple genes involved in regulation of stomatal opening and closing, particularly the gene, and several genes related to cell wall biosynthesis, such as and Moreover, we found that the water use efficiency of the transgenic plants was consistently higher than that of wild type plants when subjected to chronic drought stress. Taken together, our results suggest that plays a positive role in improving drought adaptability and resistance in .