Carbon allocation and competition maintain variation in plant root mutualisms

Area of Science:

• Plant biology
• Ecology
• Evolutionary biology

Background:

• Plants form root symbioses with various organisms, providing different benefits.
• Understanding how diverse symbiotic relationships persist is crucial for plant health and ecosystem function.

Purpose of the Study:

• To investigate the persistence of symbiotic partner quality variation in plant-root interactions.
• To model population dynamics of mutualist and non-mutualist symbionts using a resource-ratio approach.

Main Methods:

• Developed a resource-ratio model of population growth for plants and their symbionts.
• Modeled plant carbon allocation strategies, distinguishing between initial symbiosis construction and post-establishment preferential allocation.
• Analyzed the interplay between carbon competition, plant fidelity to mutualists, and the costs of mutualism.

Main Results:

• Coexistence of mutualists and non-mutualists is possible under specific conditions.
• Plant fidelity to mutualists and the costs associated with mutualism are key factors mediating resource competition.
• Symbiont population dynamics are influenced by varying degrees of preferential carbon allocation, with coexistence occurring at intermediate levels.

Conclusions:

• Intermediate levels of preferential carbon allocation by plants to mutualists facilitate the coexistence of diverse symbiotic partners.
• The findings align with empirical observations and biological market theory applied to plant-root symbioses.
• This model provides insights into the ecological and evolutionary dynamics of plant-microbe interactions.