STABILIZING MECHANISMS IN A LEGUME–RHIZOBIUM MUTUALISM


By jpeza - Posted on 09 Julio 2009

Fecha Publicación: 
1 Ene 2009
Nombre de Revista: 
Datos del paper
Autor Principal: 
Katy D. Heath
Volumen: 
63
Issue: 
3
Página Inicial: 
652
Página Final: 
662
Abstract: 

Preferential rewarding of more beneficial partners may stabilize mutualisms against the invasion of less beneficial, that is cheater,

genotypes. Recent evidence suggests that both partner choice and sanctioning may play roles in preventing the invasion of

less-beneficial rhizobia in legume–rhizobium mutualisms. The importance of these mechanisms in natural communities, however,

remains unclear. We grew 12 Medicago truncatula maternal families with a mixture of three rhizobium strains from their native

range for three plant generations and estimated the symbiotic benefits (nodule number and size) conferred to each rhizobium

strain. In this experiment, the majority of M. truncatula genotypes formed more nodules with more beneficial rhizobium strains,

providing evidence for adaptive partner choice. We also found that three generations of symbiosis resulted in an increase in the

relative frequency of rhizobium strains that were most beneficial to plants—suggesting that partner choice affects rhizobium

fitness. By contrast, we found no evidence that plants differentially rewarded rhizobia postnodulation via sanctioning leading

to differences in nodule size. Taken together, our data suggest that plants have evolved to recognize beneficial rhizobial signals

during the early stages of symbiosis, and that signaling between plants and rhizobia may be subject to coevolutionary pressures

Dirección del Autor: 

1Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108

2E-mail: katy.heath@utoronto.ca

Keywords: 
Cheater
honest signal
partner choice
plant-microbe
sanctions
symbiosis.
Coautores: 

Peter Tiffin

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