Dynamics Of Soluble Sugar Contents, Antioxidative Enzymes And Endo-hormones In Bud Module Of Alternanthera Philoxeroides

Alternanthera philoxeroides (Mart.) Griseb., a perennial herb, is native in South America, and is regarded as a harmful weed in many regions over the world. It easily reproduces by the vegetative growth in China. In particular, the buds play a key role in its reproduction, spatial spread and surviving through the winter. The buds, nodes and internodes from different individuals in two habitats terraneous and aquicolous were sampled, and dynamics of soluble sugar content, three enzyme (POD, SOD and CAT) activity and two endo-hormone (GA and ABA) content were measured in a year round. This study is interesting in understanding the mechanism of its dormancy mechanism and providing insights in controlling weed. The main results were summarized as following:1. As a main reservoir of carbohydrates, soluble sugar is the base of material and energy to maintain dormancy. The soluble sugar content in different parts of A. philoxeroides from two different habitats both displayed an increase from September to December, and maintained a high level during the dormancy from December to March, then dropped from March. Meanwhile, the buds sprouting were observed since March. By comparing, it was shown that there is a significant difference of soluble sugar content between the bud and the node groups from the terraneous individuals, as well as between the bud and the internode groups, but no difference whthin the aquicolous groups.2. The changes of enzyme activity do not differ due to different habitats, but their changes are in consistent with seasonal change. i.e. the activity of enzymes is high during dormancy from November to March, and is low during growth from May to September. The pattern of CAT activity is similar to SOD with a peak in November, but different from POD which displays its highest activity in September. The increment of CAT and SOD is helpful to remove the superfluous O2 and H2O2 so that it protect buds from damages during dormancy.3. The endogenous hormone ABA,GA and GA/ABA are important indicators to plant dormancy. The dynastic of ABA and GA monitored in a year around is closely consistent with the growth and dormancy stages of A. philoxeroides. The content of ABA is significant higher in dormancy stage than that in growth stage, correspondingly, the ratio of GA/ABA is significant lower in dormancy stage than that in growth stage. In particular, the ABA acuminated more in the buds than in the nodes and internodes.In summary, A. philoxeroides appears to have developed a complex mechanism of dormancy physiologically, which make its vegetative parts such as the bud suffer from the cold habitats through the winter.