PARENT SESSION
Organized Oral Session 16: Allelopathy: Biochemical interactions among plants affecting community structure, exotic invasions and evolutionary theory
Organizer(s): A Mallik and R Callaway
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 511 C, Level 5, Palais des congrès de Montréal

Competitive self/nonself discrimination in plants.

Novoplansky, Ariel¹, ¹ Mitrani Department of Desert Ecology, Institute for Desert Research, Midreshet Ben-Gurion, Israel

ABSTRACT- Competition usually involves the allocation of limiting resources to non-reproductive functions. Natural selection is expected to favor mechanisms that increase competition with nonself neighbors and limit wasteful competition with self. We compared the growth of plants that were grown in the presence of neighbors that belonged to the same physiological individual, were separated from each other for variable periods, or originated from adjacent or remote tillers on the same clone. The results demonstrate that Pisum sativum, Buchloe dactyloides and Trifolium repens plants are able to differentiate between self and nonself neighbors and develop fewer and shorter roots in the presence of other roots of the same plant. Furthermore, once Buchloe dactyloides cuttings that originate from the very same node are separated they become progressively alienated from each other and eventually relate to each other as genetically alien plants. The results suggest that the observed self/nonself discrimination is mediated by physiological coordination among roots that developed on the same plant rather than allogenetic recognition. The observed physiological coordination is based on, an as yet, unknown mechanism and has important ecological implications for it allows the avoidance of competition with self and the allocation of greater resources to alternative functions.

Key words: Self/nonself discrimination, Competition, physiological coordination, phenotypic plasticity