Overexpression and suppression of violaxanthin de-epoxidase affects the sensitivity of photosystem II photoinhibition to high light and chilling stress in transgenic tobacco.

Tobacco (Nicotiana tabacum) transformed with the sense and antisense constructs of tomato (Lycopersicon esculentum) violaxanthin de-epoxidase gene (LeVDE) was obtained under the control of the cauliflower mosaic virus 35S promoter (35S-CaMV). Reverse transcription-polymerase chain reaction and western blot analysis demonstrated that the exogenous gene was integrated into the tobacco genome. Wild type (WT), the sense-transgenic line T(1)-24(+) and the antisense-transgenic line T(1)-17(-) were used for physiological measurement. The ratio of (A+Z)/(V+A+Z) and non-photochemical quenching in WT were lower than that in sense plants and higher than that in antisense ones under high light and chilling stress with low irradiance. The maximal photochemical efficiency of photosystem II (PSII) (Fv/Fm) and the net photosynthetic rate (Pn) in the sense line decreased less, while Fv/Fm and Pn in the antisense line decreased most obviously among all lines. These results suggest that the expression of the violaxanthin de-epoxidase gene in transgenic plants affects the sensitivity of PSII photoinhibition to high light and chilling stress.