Expression Of CMO Gene In Transgenic Tobacco Driven By CMO Promoter

Betaine is a non-toxic osmopretectant which protects the cell from salt or drought stress by maintaining an osmotic balance with the environment. In plants,glycine betaine is synthesized via the two pathway from choline, and the first step is catalyzed by choline monooxygenase (CMO).Our preliminary work showed that CMO gene promoter (pC: -267 ~ +1bp) is salt-induced promoter. Compared to noninductive leaves, the GUS enzyme activity driven by CMO promoter was enhanced 5-fold in transgenic tobacco leaves in the presence of 400mmol/L NaCl. In this article, the pCAMBIA1301-pC-CMO was constructed and transferred into tobacco. The expression of CMO gene in transgenic plants was analysed.The 1.3 kb coding region of CMO gene was amplified from cloning vector pUC19-CMO by PCR. CMO gene was inserted into pCAMBIA1301-pC-GUS by replacing GUS gene, and the new expression vector, pCAMBIA1301-pC-CMO was obtained. Then pCAMBIA1301- pC-CMO was transferred into Agrobacterium tumefaciens strain LBA4404.pCAMBIA1301-pC-CMO, pBI121-CMO(35S-CMO) were transferred into tobaccos (Nictiana tabacum L. cv. 89) via Agrobacterium mediation. PCR positive tobaccos were obtained. Semi-Quantitative RT-PCR detection showed that CMO gene has expressed in two types transgenic tobaccos. The expression of CMO gene in pC-CMO transgenic plants is lower than that in 35S-CMO transgenic plants. Betaine content analysis in the transgenic tobacco leaves showed that the betaine content in pC-CMO transgenic plants is less than that in 35S-CMO transgenic plants.Under 100 mmol/L NaCl stress, Semi-Quantitative RT-PCR detection showed that the expression of CMO gene in plants was different. The expression of CMO gene in pC-CMO transgenic plants is higher than that in 35S-CMO transgenic plants. Further detection showed that the betaine content in pC-CMO transgenic plants is more than wild type and35S-CMO transgenic plants. The results showed that under salt stress the expression of CMO gene driven by CMO promoter increased in transgenic plants..