Poster: Seed biology

Abs # 723: Plants selected for high levels of seed dormancy also exhibit bud dormancy in their rhizomes.

Presenter:	Robinson, David L., drobinson@bellarmine.edu
Authors	Robinson, David L. (A)   Lau, Joann M. (B)
Affiliations:	(A): Bellarmine University (B): University of Illinois at Urbana-Champaign

Eupatorium rugosum Houtt (Ageratina altissima [L.] King & Robinson), commonly known as White Snakeroot, is a native, weedy plant that grows in shaded areas along the margins of woodlands and waterways throughout the midwestern U.S. This perennial species produces rhizomes with vegetative buds that overwinter and emerge in the spring. Seeds from a single population (from Louisville, KY) were screened for differential germination-response to cold treatment, and then grown to maturity in the same environment. After only two cycles of recurrent selection, non-dormant lines showed 74% germination prior to cold treatment (post-imbibition), whereas dormant lines only exhibited 17% germination before cold treatment. This recurrent-selection program was carried out for four years and has resulted in Eupatorium plants that produce seeds with broadly divergent levels of primary dormancy. This shows that primary dormancy in the seed of this species is under some level of genetic control. For the past four years we have observed that plants producing seeds with lower levels of dormancy tend to produce rhizomes with perennating buds that break dormancy earlier in the spring than plants producing seeds with higher levels of dormancy. In March of these years, plants that produced non-dormant seeds had young shoots that were, on average, five times taller than the shoots from plants that produced dormant seeds. Perhaps some common regulatory elements control dormancy in both the seed and vegetative buds of this species.