The genetic engineering of glycine betaine synthesis in tobacco improves the resistance of the photosynthetic apparatus to drought stress.

In recent years, with the global climate change, the intensity, frequency and duration of drought have increased significantly, which has become the main limiting factor for agricultural development in many areas. Glycine betaine (GB) is an effective stress-resistant substance. In this experiment, the effects of the genetic engineering of GB synthesis on photosynthetic apparatus of tobacco under drought stress were studied using transgenic tobacco (T) accumulating GB and wild-type tobacco (K326, WT). Potted tobaccos were subjected to drought stress (controlled irrigation, 25 °C ± 1 °C, a relative humidity: 75–80%) for 9 days, photosynthetic gas exchange parameters, chlorophyll a fluorescence, structure of chloroplast and thylakoid membrane, and protein function of thylakoid membrane were examined under different drought stress time (days). The results showed that T tobacco could accumulate GB and the accumulated GB improved the resistance of the photosynthetic apparatus to drought stress. Under drought stress, the damage of chloroplast and thylakoid lamellae in T tobacco was less than that in WT tobacco, the accumulation of GB in T tobacco could maintain the stability of thylakoid membrane, improved the unsaturated fatty acid index (IUFA) of thylakoid membrane lipid, increased the contents of digalactosyl diacylglycerol (DGDG) and phosphatidylglycerol (PG), and decreased the ratio of monogalactosyl diaylglycerol (MGDG) to DGDG. In addition, under drought stress, the accumulation of GB in T tobacco alleviated the photo-inhibition of PSII, and the increase of xanthophyll cycle de-epoxidation may be one of the reasons for the enhancement of PSII function. [ABSTRACT FROM AUTHOR]