ARBUSCULAR MYCORRHIZAL FUNGI ASSOCIATED WITH MAIZE CROP IN DROUGHT REGIONS OF OAXACA

Abstract

Under stressful environments, plants associate with microbiota to adequately fulfill multiple functions. The plant-arbuscular mycorrhizal fungi (AMF) association is one very important by which plants satisfy part of their water and nutritional needs. The knowledge of native AMF is a key factor in the development and application of this biotechnology in crops of socioeconomic importance, such as maize. The objective was to know the diversity of AMF and the extent of mycorrhizal colonization in maize plots in four regions with drought incidence. A significant association is expected between soil properties and spore abundance, species richness, and mycorrhizal colonization. Random sampling was carried out in four regions of the state of Oaxaca (Istmo, Sierra Norte, Mixteca and Valles Centrales) and the relationship of soil physicochemical properties with species richness, spore abundance, and percentage of colonization was analyzed using the redundancy technique. A total of 24 AMF species were recorded, of which Funneliformis geosporum and Rhizophagus intraradices are present in the four regions studied. The association of AMF with roots of maize plants was greater than 60%. The highest spore abundance was recorded in the Sierra Norte region. No significant differences in species richness were observed among regions or by season; however, the Valles Centrales region had the highest diversity index. Concentrations of moisture, total nitrogen, electrical conductivity, and available phosphorus in the soil were correlated (p≤0.05) with mycorrhizal diversity in the study regions. These findings indicate that the diversity of mycorrhizal fungi in the study plots is high, as well as the levels of mycorrhizal colonization (>60%). In addition, five new genera are reported for Oaxaca. This highlights the need to continue the evaluation of mycorrhizal diversity in the state.