Polymorphic responses of Medicago truncatula accessions to potassium deprivation.

Potassium (K+) is an essential macronutrient for plants and the most abundant cation in cells. Due to variable K+ availability in the environment, plants must be able to adjust their developmental, physiological and transcriptional responses. The plant development to K+ deprivation was not well studied in legumes thus far. We recently described the first adaptation mechanisms of the model legume Medicago truncatula Jemalong A17 to long-term K+ deprivation and analyzed these responses in the context of arbuscular mycorrhizal symbiosis. Here we report polymorphic growth variations of two genetically very different accessions of M. truncatula to K+-limiting conditions, Jemalong A17, and the Tunisian accession Tn11.1. The faster adaptation of Tn11.1 than A17 to K+ shortage might be due to its greater adaptation to saline soils. Examining in a more systematic way the developmental adaptation of various M. truncatula accessions to K+ deprivation will provide a better understanding of how legume evolved to cope with this stressful condition.