O papel de fungos micorrízicos arbusculares na tolerância do feijão comum ao crômio

Abstract

Chromium (Cr) is a heavy metal that, in high concentrations, has negative effects on health and on the development of food crops, consequently, on food security. The hexavalent form is the most harmful and can reduce plant metabolism, altering structures and consequently modifying the activity of antioxidant enzymes. The bean crop (Phaseolus vulgaris) is of great national importance and can be cultivated in a wide range of environments. Therefore, it is imperative to develop sustainable technologies that can reduce the contamination of plants and grains by Cr. Arbuscular mycorrhizal fungi (AMF) are recognized for establishing symbiotic relationships with bean roots. In this sense, the aim of this study was to evaluate the influence of two AMF species on the antioxidant activity of P. vulgaris plants subjected to Cr.The plants were grown in a growth chamber in three-liter pots containing topsoil and inoculum of Rhizophagus clarus and Claroideoglomus etunicatum, with or without application of Cr in the soil. Upon reaching the fourth vegetative stage, measurements of gas exchange, electron transport rate, biochemical activities, Cr content, mycorrhizal colonization rate and plant growth were evaluated. The activities of antioxidant enzymes in beans containing or not chromium did not obtain significant results, but inoculations with AMF R. clarus increased the content of malondialdehyde, hydrogen peroxide and proline in plants containing the heavy metal. In the control treatment and in the one inoculated with C. etunicatum there was an increase in the proline content in the plants with the contaminant compared to the untreated ones.In view of this, it is possible to state that oxidative stress in plants is observed by the compromise of membrane integrity and indication of greater lipid peroxidation in plants treated with R. clarus, which also showed sensitivity to stress, explaining the increase in proline content. The mycorrhizal colonization rate was higher in plants that did not receive the metal, demonstrating that both species are sensitive to chromium.