Relationship between root traits and arbuscular mycorrhizal fungi in three species of weeds with different synanthropy index

Background: Nutrient foraging strategies between thin and thick roots, including mycorrhizal symbionts are resource-costly, and therefore a trade-off could exist. These strategies can vary with the synanthropy index (degree to which a species associates with anthropogenic habitats), thus maximizing the benefits for the acquisition of soil resources. Objectives: To quantify the arbuscular mycorrhizal colonization of Melampodium species with different synanthropy index, and to determine the correlations between arbuscular mycorrhizal colonization and the architectural and morphological root traits. Methods: Roots of Melampodium divaricatum, M. perfoliatum and M. tepicense, with highest to lowest synanthropy index, respectively were collected. The root branching rate (RBR), total root length (TRL), diameter of first-order root, (FOR), root tissue density (RTD), specific root length (SRL), and arbuscular mycorrhizal colonization were quantified. Additionally, soil chemistry analyses were done. Results and conclusion: Melampodium tepicense had lowest FOR, highest SRL and lowest arbuscular mycorrhizal colonization, whereas M. divaricatum and M. perfoliatum had the opposite values. Additionally, M. divaricatum and M. perfoliatum had higher TRL, RTD, and RBR, suggesting that both strategies, arbuscular mycorrhiza and fine roots, are used for acquisition of nutrients, independently of their phylogenetic relationship and soil nutrients.