Endo-Glycanhydrolases Activities in Artemisia sphaerocephala (Asteraceae) Mucilaginous Achene Germination Process

摘要

Artemisia sphaerocephala is a sand-fixing shrub occurring in the deserts of Northwest China. The polysac-charide pellicle that surrounds the achene forms during seed development and becomes a thick mucilaginous layer when the dry seed is wetted. In natural habitats, the ach-enes start to mature from September to October. The mature achenes, enclosed in their dry polysaccharide pellicles , are dispersed by wind and adhere to sand grains by the mucilaginous layer that develops from the pellicle when the achene surface is wetted. A major component of the mucilage on the exterior of the pericarp is pectin. The thick pellicle of these species serves as a means of water catchment as well as helping the seed adhere to sand particles . Strong adherence to the sand surface once the mucilage is dry prevents further dispersion by rain and wind and deters collection by ants and other seed predators. The following question is frequently asked: are the mucilaginous pellicles of these desert seeds utilized as a nutrition source at seed germination? In this work we studied the development of endo-glycanhydrolases which could potentially degrade the polysaccharide complement of the pellicle of A. sphaerocephala at early stages of seed germination.