Knockdown of Confers Drought Resistance and Promotes Lateral Shoot Growth in Hybrid Poplar ( × var. ).

Plants have evolved defense mechanisms to overcome unfavorable climatic conditions. The growth and development of plants are regulated in response to environmental stress. In this study, we investigated the molecular and physiological characteristics of a novel gene in hybrid poplar ( × var. ) under drought stress. a stress-associated protein (SAP) family gene, encodes a putative protein containing an A20 and AN1 zinc-finger domain at its N- and C-termini, respectively. Knockdown of transgenic poplars (-Ri) enhanced their tolerance to drought stress compared with wild type plants. Moreover, the RNAi lines showed increased branching of lateral shoots that led to a gain in fresh weight, even when grown in the living modified organism (LMO) field. In -Ri transgenic plants, the expression levels of genes involved in axillary bud outgrowth and cell proliferation such as , and were increased while the gene which involved in bud dormancy was down-regulated. Taken together, these results indicate that represents a promising candidate gene for engineering trees with improved stress tolerance and growth during unfavorable conditions.