Cloning And Characterizing Of Fructose-1,6-Bisphosphate Aldolase Gene PeALD Of Populus Euphratica Oliv

Being a stress-resistant tree species, Populus euphratica exhibits a typically high capacity to tolerate salinity. Transcriptomic studies of P. euphratica have shown that fructose-1,6-bisphosphate aldolase (PeALD) was up-regulated by NaCl stress, indicating that this enzyme may contribute to salt tolerance of P. euphratica.To analyze the role of PeALD in salt tolerance, full length cDNA of ALD was cloned from P. euphratica by RT-PCR. Meanwhile over expression of PeALD in tobacoo was conducted by transferring a PeALD construction into tobacoo genome and the salt-resistant characters of the transgenic lines were analyzed.The result of our study indicated that the cloned cDNA was the ALD ortholog of P. euphratica based on Blast analysis, encoding a hydrophobic protein of 247 amino acids with a theoretical isoelectric point of 6.84 and a molecular mass of 26.79 kd. The data of PCR and RT-PCR indicate that the PeALD was integrated into tebacoo genome and over-expressed in four transgenic lines. Salt-tolerance test shows that transgenic plantlets survived in MS medium with 200 mmol/L NaCl after 15 d culture and plant growth was not inhibited. In contrast, the leaf of wild-type plantlet got etiolated and shrinked after 15 d culture at the same saline condition. The data of photosynthetic study show that over-expression of PeALD attenuated the NaCl-induced reduction of net photosynthetic rate in transgenic plants, presumably resulting from an enhanced turnover rate of the Calvin cycle. The stable carbon assimilation is favorable for respiration maintenance, leading to a constant ATP supply by oxidative phosphorylation, which benefits H+-ATPase to energise salt transport through the plasma and vacuolar membranes.In conclusion, our study demonstrate that ALD gene cloned from P. euphratica was able to enhance the capacity for salt tolerance of model plants, but the role of PeALD in salt stress signaling needs further study.