Involved in multiple pathways to improve stress tolerance phenotypes, which could not be achieved by single gene transformation studies. The combined effects from multiple genes resulted in highly complex traits, and future studies comparing these multigene AbMole Butylhydroxyanisole transformed poplars with individual gene transformants may help to better identify the relationships between the traits and the transgene functions. At the end of the drought and salt stress period, the transgenic lines were found to have better growth than the control, as shown by greater height, basal diameter and biomass. This improved growth could be primarily attributed to higher WUEi for the D520 and D5-21 transgenic lines, since it was an important indicator of plant yield. Fructan levels in the transformants were significant higher than the controls under drought conditions. These results were consistent with other works showing that sugar beet or tobacco transformed with SacB also displayed AbMole Sibutramine HCl increased levels of fructan. It was proposed that fructan could protect membranes by interacting with lipids and phospholipids. Although previous reports demonstrated that SacB was involved in drought tolerance, the enhanced salt resistance phenotype has not yet been observed in SacB transformed plants. A previous study showed that expression of SacB also increased the levels of total non-structural carbohydrates in potato. Since other non-structural carbohydrates could be related to osmotic stress tolerance, the potential increase in total nonstructural carbohydrates in the transgenic poplar trees should to be evaluated in the future. On the other hand, our previous work revealed that the introduction of JERF36 into poplar enhanced salt tolerance in both greenhouse and field experiments, and we proposed that expression of JERF36 was the major contributor to the phenotype. In this study, the D5-20 and D5-21 transgenic lines displayed increased WUEi and root biomass, which suggested that JERF36 could regulate plant WUE and root growth under salt stress. Although higher WUEi and better root growth were also observed on transgenic plants under drought stress, whether SacB was involved in plant WUE regulation or root architecture remained to be determined since potential effects on drought tolerance of JERF36 could not be unambiguously interpreted from the present data. Although no previous data are available on the function of JERF36 under drought conditions, recent work by Wu et al. suggested that another ERF gene, JERF3, could confer drought tolerance in transgenic tobacco. While this finding implied that JERF36 may have play a significant role in drought tolerance in this study, the assumed interaction or crosstalk between JERF36 and SacB in multigene transformed poplar requires further investigation. Proline accumulation under abiotic stress conditions has been correlated with protection of subcellular structures by osmotic adjustment and free radical detoxification. Increased proline was also shown to play a role in enhancing photosynthesis efficiency.