2022 journal article
Mycorrhiza-mediated potassium transport in Medicago truncatula can be evaluated by using rubidium as a proxy
PLANT SCIENCE, 322.
Arbuscular mycorrhizal (AM) fungi considerably improve plant nutrient acquisition, particularly phosphorus and nitrogen. Despite the physiological importance of potassium (K + ) in plants, there is increasing interest in the mycorrhizal contribution to plant K + nutrition. Yet, methods to track K + transport are often costly and limiting evaluation opportunities. Rubidium (Rb + ) is known to be transported through same pathways as K + . As such our research efforts attempt to evaluate if Rb + could serve as a viable proxy for evaluating K + transport in AM symbiosis. Therefore, we examined the transport of K + in Medicago truncatula colonized by the AM fungus Rhizophagus irregularis isolate 09 having access to various concentrations of Rb + in custom-made two-compartment systems. Plant biomass, fungal root colonization, and shoot nutrient concentrations were recorded under sufficient and limited K + regimes. We report that AM plants displayed higher shoot Rb + and K + concentrations and a greater K + :Na + ratio relative to non-colonized plants in both sufficient and limited K + conditions. Consequently, our results indicate that Rb + can be used as a proxy to assess the movement of K + in AM symbiosis, and suggest the existence of a mycorrhizal uptake pathway for K + nutrition in M. truncatula.