Poster: Photosynthesis

Abs # 340: Effects of photoperiod on whole-plant carbohydrate partitioning, crown bud development, and gene expression in leafy spurge (Euphorbia esula, L.).

Presenter:	Anderson, James V, andersjv@fargo.ars.usda.gov
Authors	Anderson, James V (A)   Gesch, Russ W (B)   Horvath, David P (A)
Affiliations:	(A): USDA/ARS, Bioscience Research Laboratory (B): 2USDA/ARS, North Central Soil Conservation Research Lab

Leafy spurge is an invasive perennial weed that propagates vegetatively from an abundance of adventitious buds located on the crown and roots. These buds develop during the growing season but are not capable of generating a new plant unless the aerial portion of the plant is removed. Studies have shown that signals from leaf tissue are capable of maintaining correlative inhibition in crown and root buds. Field data collected over three growing seasons also suggest a correlation between developmental status of crown buds and seasonal photoperiod. In this study, we examine seasonal trends in photosynthesis and whole-plant carbohydrate partitioning to determine correlations that may exist with influencing crown bud development and gene expression. Photosynthesis and carbohydrate measurements were obtained from plants in partial root containment grown outdoors in full sun. Leaf photosynthesis was greatest in late May and was relatively stable from June to August before sharply declining between August and October. Between August and October the greatest increase in average crown bud development occurred (6.1 cm as compared to an average of 1.2 cm between June and August). Total nonstructural carbohydrates in aboveground plant tissues followed predictable patterns. Starch and sucrose content steadily rose in crown buds as they developed throughout late summer, while hexoses remained unchanged. Between late September and the end of October, crown bud sucrose increased 3-fold corresponding to a sharp decline in starch. Starch in the stem and leaf also declined by 9- and 6-fold, respectively, between August and October. Gene expression patterns observed in crown buds collected during the growing season will be presented and discussed in relation to photoperiod.