Studies On The Expression Of The Salicornia Choline Monooxygenase (CMO) Gene In Transgenic Tobacco Plants And Their Salt Stress Tolerance

Betaine will be accumulated in plants in response to drought and salinity stress. The betaine accumulation plays an important role in improving osmotic adjustment capacity and protecting cell membrane, because betaine is a very effective osmoprotectants. Choline monooxygenase(CMO)is the rate-limited enzyme in the pathway to synthesize betaine, therefore the CMO gene is regarded as the most hopeful one of stress-tolerance genes. The CMO gene cloned from Salicornia europaea was transferred into tobacco (Nictiana tabacum L. cv. 89) via leaf disc mediated by Agrobacterium GV 3101(Agribecterium tumefaciens). PCR, Southern blotting and RT-PCR analysis showed that the CMO gene was integrated into tobacco's genome and expressed on the level of transcription. The experimental results indicated that the damage of salt to transgenic tobacco was lighter than the control in the same salt concentration treatment. In salt-stress condition, the content of chlorophylls, betaine accumulation, superoxide dismutase(SOD) and peroxidase (POD) activities of transgenic plants were generally higher than those of the control, while relative electronic conductivity and water lose rate of transgenic plants were generally lower than those of the control. These results showed that the transformed CMO gene contributed to improved salt resistance of the transgenic tobaccos.