Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 26, 2007
Publication Date: February 1, 2008
Citation: Chao, W.S., Anderson, J.V., Horvath, D.P. 2008. Changes in well-defined phases of bud dormancy associated with shifts in carbohydrate metabolism may involve beta-amylases. Meeting Abstract. Weed Science Society of America Meeting Abstracts. Presentation 63.
Leafy spurge is a noxious perennial weed that infests range lands in the Northern Great Plains. It is being used as a model to investigate dormancy in underground adventitious buds, i.e., root and crown buds. Underground adventitious buds of leafy spurge (Euphorbia esula) are 1) maintained in a quiescent state through correlative inhibition (paradormancy) during the normal growing season, 2) inhibited from initiating post-senescence shoot growth in the fall by innate dormancy (endodormancy), and 3) maintained in a state of ecodormancy during overwintering. Carbohydrates appear to be involved in the development and release of bud dormancy during these seasonal cycles. In this study, relationships between carbohydrate metabolism and bud dormancy were examined in response to both seasonal signals and growth induction by decapitation. Seasonal signals caused sucrose levels to increase in Nov and Dec, whereas starch levels decreased progressively from Aug to Dec. In contrast, after paradormancy release, sucrose levels decreased significantly one day after decapitation and stayed at similar levels until day 5. Starch levels also decreased quickly and continuously from day 1 to day 5 after decapitation. Real-time PCR was used to determine if shifts in carbohydrate contents correlate with the expression levels of carbohydrate metabolism genes. Our results indicated that many of these genes were differentially-regulated. Among them, the expression of a specific beta-amylase gene increased 100-fold after growth induction by decapitation. Beta amylase transcript levels increased 16,000-fold from July to December. Sequence data analysis indicated that this beta-amylase was represented by two genes, Amy1 and Amy2. We are in the process of determining the expression of these two genes using gene-specific primers and antibodies. Combined, current results indicate that this beta-amylase may play an important role in starch degradation during paradormancy release and endodormancy development.