PARENT SESSION
Oral Session #22: Plant function and response to stress. Presiding: K. Miyanishi.
Tuesday, August 7, 2001. 8:00 AM to 11:45 AM. Hall of Ideas P&Q.
Clones recover from prolonged dormancy induced by severe stress.
Morrow, Patrice1, Olfelt, Joel2, 1 2
ABSTRACT- Many plant species in temperate, boreal and alpine floras propagate clonally, which can allow genets (genetic individuals) to tolerate periods of reproductive failure, and obtain great size and age. However, genets remain vulnerable to herbivores, pathogens and other disturbance. For 10 - 15 years we monitored 140 clones of Solidago missouriensis, goldenrod, at Cedar Creek Natural History Area in Minnesota. Our sample included clones apparently killed through defoliation by a specialized beetle, Trirhabda canadensis. Some of these "dead" clones have reappeared 1 to >13 years after defoliation; entire or large segments of their original territories (80 - 500 m2) are vigorously recovered in a single year. We have rejected two hypotheses explaining this phenomenon. (1) Reclamation of so large an area in one season could not occur via spread from occasional ramets that might survive defoliation because rhizomes are too short. (2) A rash of seedling establishment could not create this phenomenon because RAPD analyses show that ramets of recovered clones are one genotype. Goldenrods are self-incompatible and seeds are tiny. If seeds were the source of ramets in recovered clones, they would be of many genotypes. We hypothesize that severe stress triggers changes in allocation patterns of storage compounds to allow prolonged dormancy and robust recovery in more favorable circumstances.
KEY WORDS: Solidago missouriensis, Trirhabda canadensis, carbohydrate allocation, plant stress response