INFLUENCE OF ARBUSCULAR MYCORRHIZAL FUNGI (AMF) ISOLATED FROM ARID ZONES ON PLANT GROWTH, PROTEIN CONCENTRATIONS AND RESPONSE TO SALINITY CONDITIONS IN ALFALFA (MEDICAGO SATIVA)

Abstract

The present study is aimed to isolate native effective species of arbuscular mycorrhizal fungi from the Qatari environment and to subject these isolates for evaluation to support the growth of Medicago sativa under saline environment, as well as to study the effect of the isolated AMF on Alfalfa wilt caused by F. oxysporum. At the species level, 13 mycorrhizal fungi have been recorded. The AMF from different samples were identified based on the sequencing of the PCR product of the amplified conserved ITS region. The collected species belong to 16 genera, 3 different orders and 6 families. The results showed that Tamarix aphylla recorded to be with highest AMF infection rate (100%) while the lowest value (12%) was attributed to Zygophyllum qatarense. The isolated AMF species were then used in two different research investigations. The first was to study the effect of AMF on alfalfa plant growth under salinity stress which was conducted in two conditions, greenhouse and field conditions. Saline irrigation reduced growth (biomass), chlorophyll and protein content significantly. Potassium, phosphorus, and magnesium uptake were also significantly reduced, whereas sodium uptake increased as compared to AMF-inoculated and control plants. In both experiments, the results of inoculation with AMF were better than non-inoculated in terms of plant growth, chlorophyll content, enzyme activity, protein content, and nutrients uptake. The second experiment looked into the effect of the AMF on Alfalfa wilt caused by F. oxysporum. Our findings showed that AMF can help to mitigate the negative impacts of Fusarium oxysporum stress on alfalfa by improving the plant's general health. This thesis highlights, for the first time, the role of native isolated arbuscular mycorrhizae to enhance Medicago sativa plant under salinity and disease stress. Because all our isolates come from arid environments, these AMF could help conserve biodiversity in desert areas. Therefore, the knowledge about the community of AMF in Qatari rhizosphere is important for possible application of such mutualistic association as an alternative biological mechanism to mitigate the negative effects of abiotic stress and use them as biofertilizers and/or biopesticides in arid environments to enhance sustainable agriculture systems.