Expression of Choline
Oxidase Gene (codA) Enhances Salt
Tolerance of the Tobacco
HE Pei-Min1,3*, ZHANG Da-Bing2, LIANG
Wan-Qi2, YAO Quan-Hong2, ZHANG Rong-Xian1
(1Nanjing Agriculture University, Nanjing 250095, China； 2Agriculture Institute of Shanghai,
Shanghai 201106,
China；3Shanghai Fisheries University, Shanghai 200090, China)
Abstract The codA
gene for choline oxidase, which converts choline into betaine. This enzyme,
cloned from a soil bacterium Arthrobactor globiformis, has been
transferred and expressed in tobacco by the Agrobatcterium-method
transformation through the binary plasmid pGAH/codA. The pGAH/codA carried with
KmR and HygR,and coding sequence for a transit
peptide from Rubisco small subunit gene (rbcS) was inserted between 35
S promoter and codA, so that the COD could be introduced into the
chloroplast by this transit peptide. The transformed plants were screened on
the medium containing the Km and Hyg. PCR, Western and gold immunolocalization
tests showed that the codA gene has integrated into the tobacco DNA
genome and its protein was expressed and the mature peptide has gone into the
chloroplasts by the transit peptide. The results of salt tolerance measuring
for transgenic plants showed that the transgenic plants were more tolerance to
the salt than the control plants. The young transgenic plants (1.0–1.5 cm)
could survive at 400 mmol/L NaCl MS medium for more than 30 days. From them the
higher tolerance plant T4-400 was obtained, which could grow at the 300 mmol/L
NaCl MS medium well. The transgenic plants (6–8cm) could grow normally at the
400 mmol/L NaCl MS medium while wild plants failed to do so. So the transferred
plant with codA enhanced its tolerance to the salt stress.
Key words tobacco；codA gene； transgenic plant； expression； salt resistance
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