The water deficits limit the growth and development of agricultural and forest organisms. The AP2/ethylene response factor (ERF) family has been identified as one of the largest plant-specific transcription factors (TFs) essential for plant development and stress response. The function of PtaERF194 in growth and drought tolerance was detected in the overexpression (OX) and RNA interference (RNAi) transgenic poplar 717 hybrids (Populus tremula × Populus alba). Plant growth, stem vessels, water-use efficiency (WUE), chlorophyll content and PtaERF194 co-expressed genes were analyzed using morphological, physiological and molecular methods. Overexpression seedlings showed a shorter and smaller phenotype along with smaller and more vessels compared with the wild-type (WT). Physiological indices indicated that OX with low transpiration and stomatal conductance improved the tolerance to drought by enhancing WUE, limiting water loss and maintaining high water potential. A total of 12 differentially expressed genes co-expressed with PtaERF194 were identified, and they worked together to regulate drought tolerance through the abscisic acid signaling and reactive oxygen species scavenging processes. However, RNAi plants showed similar morphology and physiology to WT, suggesting that the function of PtaERF194 was redundant with other ERF TFs. The findings of the current study may shed new light on the positive function of ERF TFs in plant drought stress tolerance.
Keywords: ERF194; drought stress; plant growth; transgenic poplar; water-use efficiency.
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