Ectopic Expression of FaDREB2 Enhances Osmotic Tolerance in Paper Mulberry

Dehydration-responsive element binding （DREB） proteins are a subfamily of AP2/ERF transcription factors that have been shown to improve tolerance to osmotic stresses in plants. To improve the osmotic stress tolerance of paper mulberry （Broussonetia papyrifera L. Vent）, an economically important tree, we transformed it with a plasmid carrying tall fescue （Festuca arundinacea Schreb） FaDREB2 under the control of CaMV 35S. The ectopic expression of FaDREB2 did not cause growth retardation, and the paper mulberry seedlings expressing FaDREB2 showed higher salt and drought tolerance than wild-type plants （WT）. After 13 d of withholding water, or 15 d in the presence of 250 mM NaCI, all the WT plants died, while the plants expressing FaDREB2 survived. The FaDREB2 transgenic plants had higher leaf water and chlorophyll contents, accumulated more proline and soluble sugars, and had less membrane damage than the WT plants under high salt and water-deficient conditions. Taken together, the results indicate the feasibility of improving tolerance to multiple environmental stresses in paper mulberry seedlings via genetic engineering, by introducing FaDREB2, which promotes the increased accumulation of osmolytes （soluble sugars and proline）, to counter osmotic stresses caused by abiotic factors.

Fine-Tuning of Structural Distortion and Magnetic Anisotropy by Organosulfonates in Octahedral Cobalt(Ⅱ)Complexes

Precise modulation of the magnetic anisotropy of metal ions remains highly important for the development of high–performance single-molecule magnets(SMMs).We herein reported the synthetic,structural,spectral,magnetic,and computational studies on four mononuclear Co^(Ⅱ) complexes in a distorted octahedral environment.The change of the organosulfonate anions triggers significant modification of the distorted octahedral CoN6 coordination sphere,which enables us to tackle the influence of the structural distortion on the magnetic anisotropy in these complexes.Magnetic measurements revealed that the four complexes possess easy–plane magnetic anisotropy with large and positive zero-field splitting parameters,which decrease with the increasing distortion of the pseudo–octahedral Co^(Ⅱ) coordination geometry.This correlation was further confirmed by high–frequency/–field EPR(HF–EPR)spectra and theoretical calculations.Dynamic magnetic susceptibility measurements indicate that these complexes both exhibit slow magnetic relaxation under an external dc field,indicating the field-induced single-ion magnets(SIMs)of the four complexes.These results indicate that structural distortion plays an important role in the magnetic anisotropy of CoⅡcomplexes and should be carefully considered in the design of molecular complexes with high magnetic anisotropy.