Efecto De Diferentes Niveles De Diversidad Microbiana Del Suelo En La Relación Simbiótica Planta – Hongo Micorrízico Arbuscular

Abstract

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts that stimulate plant development from the colonization of root tissues in more than 80% of plants. There are many benefits of this relationship, such as increasing the absorption surface of the root, facilitating the uptake of insoluble phosphorus, increasing resistance to pathogens, among others; consolidating them as organisms of high importance for the development of plants. Just as AMF, other microorganisms that make up the high microbial diversity of the soil, such as bacteria, maintain a complex network of interactions that may affect mycorrhizal colonization (CM) and establish a synergistic relationship with AMF; However, there are theoretical gaps regarding this dynamic. The objective of this research was to evaluate the effect of different levels of microbial diversity in the soil, in the plant symbiotic relationship - HMA. Initially a CM experiment was carried out to select two model plants from six different plant species: Maize (Zea mays), Brizantha (Brachiaria brizantha), Crotalaria (Crotalaria juncea), Soya (Glycine max), Wheat (Triticum aestivum), and Sorghum (Sorghum bicolor) inoculated with three species of AMF: Rhizophagus clarus; Dentiscutata heterogama and Acalouspora colombiana. Subsequently, the two plant species with higher MC rates were inoculated with the three AMF species at different levels of microbial diversity, obtained from: i) successive dilutions (10-1 10-3 or 10-6); and ii) heat treatment (50, 80 or 100ºC), again evaluating the CM rate. Finally, the evaluation and correlation of MC rates of the plants was performed according to the different levels of microbial diversity, to determine their effect on the mycorrhizal relation. An indirect influence of the microbial community on MC was observed, given the restriction in the availability of soil nutrients, such as nitrogen, making mycorrhization difficult. The symbiosis of Crotalaria juncea with Rhizobium bacteria, increased mycorrhization by tripartite plant-HMA-Microbial Community interaction, different from Brachiaria brizantha where MC varied due to the decrease of the microbial community. Finally, A. colombiana and D. heterogama are possibly more resistant to soil restrictive conditions, achieving mycorrhization, unlike what happened with R. clarus, whose colonization rates varied according to alterations in soil microbial diversity. It is concluded that CM is influenced not only by microbial diversity but also by intrinsic characteristics of both the host plant and the AMF species.