The Analysis Of Drought And Salt Stress Resistance Of Transgenic Poplus Simonii×P. Nigra Pollen Plantlets Overexpressing Lea Gene

In this study, the gene encoding lea (late embryogenesis abundant) protein obtained from Tamarix androssowii was transformed into Poplus simonii×P. nigra pollen plantlets through Agrobacterium-mediated genetic transformation. After comparing the resistant abilities between the transgenic plants and the non-transgenic lines in the salinity and drought stress, the excellent clones with better resistance were selected.Eleven resistant lines were obtained through kanamycin selection, and all subjected to PCR assay and all showed positive. In PCR-Southern hybridization, all the transgenic plants showed positive signals, indicating that lea gene has been integrated into the genome of Poplus simonii×P. nigra pollen plantlets. After a further examination by Northern blotting hybridization and reverse transcription-PCR, they also demonstrated that the transformed gene had expressed at the RNA level.The 11 transgenic plants have been tested under salt and drought stress respectively. The changes of these indicators including Maleic dialdehyde content, relative conductivity, peroxidase activity, chlorophyll content (Chl), net photosynthetic rate (Pn) have been determined. These results indicated that under 200 mmol. L^-1 NaCl treatment after 6 days the POD activity showed no remarkable regular changes and that the average MDA contents and membrane relative permeation 14.4％and 14.5％lower than the contrast ones respectively, while the average Chl and Pn have a 140％and 15.8％higher than the contrast ones. All the analysis on resistant to salinity indicated that the resistance to salinity degree was T11＞Y1＞T14＞T6＞T3＞T10＞T5＞T13＞T4＞T9＞T7＞CK. Taking all the results obtained from above into consideration, the transgenic plants got less injury and showed stronger resistance to the salinity than the contrast ones under salinity stress.After seven-day drought stress, the transgenic Poplus simonii×p. nigra Pollen plantlets have average 11.41％less relative conductivity and 17.71％lower than the contrast ones. Meanwhile, the POD activity showed no remarkable regular change patern. Also, the average Chl of the transgenic plants were 14.57％higher than the contrast ones while the average Pn were 31.5％higher that the contrast ones. The comprehensively analysis on the resistance to drought indicated that the drought resistance degree is T11＞T9＞T14＞T1＞T13＞T7＞T10＞T3＞T6＞T4＞T5＞CK。All the results significantly indicatted that the drought resistance of Poplus simonii×p. nigra Pollen plantlets really got enhanced because of the transformation of the lea gene.All in all, the expression of lea gene strengthen the abilities of the drought and salinity resistance. Among them, T11 showed highest resistance and T1,T14 are inferior to it, and the other transgenic plants got remarkable resistance in comparison with the contrast ones as well.