Seasonal Changes in Soluble Sugar Contents in Different Parts of Alternanthera philoxeroides from Aquatic and Terrestrial Habitats

Exotic invasion is considered as the second factor influencing biodiversity after habitat lose. Alligator weed (Alternanthera philoxeroides Griseb.), a perennial herb native to the South America, has established itself on almost all the surface of the earth except Africa. In China, alligator weed has invaded most temperate regions where the environmental conditions, particularly temperature, are obviously different from its origin. How can alligator weed survive through cold winters is a critical issue for its establishment in these areas. In this research, we investigated the seasonal change of soluble sugars content (SSC), which presented important physiological reaction to cold acclimation, in different parts including buds, nodes, and internodes of alligator weed from aquatic and terrestrial habitats. Results showed that accumulation of soluble sugars was regularly correlated to temperature change in environment, i.e., the highest SSC in the coldest season, and the lowest in summer. Among different parts such as nodes, buds and internodes in individuals from terrestrial and aquatic habitats, accumulation of SSC presented similar results. The accumulation of SSC and its seasonal dynamics may be a physiological acclimation to low temperature so that alligator weed could establish in these regions and survive through cold winters ecologically.