Drought stress-induced autophagy gene expression is correlated with carbohydrate concentrations in Caragana korshinskii.

Autophagy has been reported to be an adapt function of plant cells under various stresses. In this report, autophagy-related gene expressions and carbohydrate concentrations in Caragana korshinskii leaf cells under drought stress were investigated. Leaf samples of C. korshinskii plants of an estimated 15-year-old were collected from three sites with different drought stress (annual precipitation range, 325.8 to 440.8 mm) at the Loess Plateau in northwestern China. Autophagy was observed in C. korshinskii samples from all three sites and was revealed by autophagosomes in the cytoplasm of mesophyll cells and increased chloroplasts degradation observed by transmission electron microscopy. Furthermore, with the drought stress increase, autophagy-related gene expressions were upregulated and leaf concentration of sucrose was increased, while concentrations of monosaccharide sugars such as glucose, fructose and galactose were decreased. The results suggested that drought stress induced autophagy gene expression, which may serve as a survival mechanism for nutrient remobilisation.