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

Directional self/nonself discrimination in roots.

Falik, Omer^*,1, Novoplansky, Ariel¹, ¹ Ben-Gurion University of the Negev, Beer-Sheva, 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 used Pisum sativum plants that had two shoots and two roots (double plants) that could be either longitudinally separated into two genetically identical but physiologically distinct individuals or left intact. Double Pisum plants were grown so each root was confronted with a root of the same plant (SELF) on one side and a root of another plant (NONSELF) on the other side. Seminal roots of intact plants developed discriminatorily longer lateral roots toward NONSELF compared to SELF neighbors and this discriminatory growth was absent in longitudinally-severed plants. The results demonstrate that Pisum plants are able to limit competition with self, based on physiological coordination among their organs rather than on allochemical recognition. It is expected that tight physiological coordination is selected for in clonal plants where there is high probability of competition with sister ramets of the same clonal genet. It is expected that self/nonself discrimination increase resource use efficiency and overall ecological performance under competitive situations.

Key words: Competition, Double plants, Split root, Physiological coordination