Enhanced tolerance of transgenic potato plants expressing choline oxidase in chloroplasts against water stress

Background: Glycinebetaine, whose biosynthesis could be catalyzed by choline oxidase (COD), is an extremely efficient compatible solute for scavenging oxidative stress-inducing molecules and protecting the photosynthetic system in plants. To study the effects of the codA transgene for choline oxidase on the drought resistance and recovery, a transgenic potato cultivar (SC) bearing codA gene and a non-transgenic (NT) control cultivar were raised in pots under moderate and severe drought stress. The experiment was constituted by a two-day-pretreatment with 20% PEG and a four-day-water stress combined with two-day-recovery treatment. Results: Under the four-day-water stress, plants were provided with normal water condition, 10% or 20% polyethylene glycol. The results of pretreatment showed an expression of codA gene in transgenic potato and an accumulation of glycine betaine (GB); leaf water potential was higher in SC than in NT. In the stress-recovery-treatment, SC showed stronger antioxidant ability, more efficient photosynthetic system, higher chlorophyll content, lower malondialdehyde content and better recovery from water deficit stress than NT. Conclusion: Although this work concentrated on the short-term water stress and recover treatments on transgenic potato plants with the over-expression of CodA gene and its control line. The datas shows that the exogenous codA gene provided potato a stronger drought resistance and recovery ability.