One AP2/ERF Transcription Factor Positively Regulates Pi Uptake and Drought Tolerance in Poplar

Drought decreases the inorganic phosphate (Pi) supply of soil, resulting in Pi starvation of plants, but the molecular mechanism of how plants, especially the perennial trees, are tolerant to drought stress and Pi starvation, is still elusive. In this study, we identified an AP2/ERF transcription factor gene, , from var. , and it was induced by both mannitol treatment and Pi starvation. Overexpressing and knocking-down of both enhanced and attenuated tolerance to drought stress and Pi deficiency compared to WT, respectively. Moreover, the overexpression of up-regulated the expression levels of Pi starvation-induced (PSI) genes and increased Pi uptake under drought conditions; however, its poplar showed the opposite phenotypes. Subsequent analysis indicated that PalERF2 directly modulated expressions of drought-responsive genes and , as well as PSI genes and , through binding to the DRE motifs on their promoters. These results clearly indicate that poplars can recruit to increase the tolerance to drought and also elevate Pi uptake under drought stress.