Identification and characterization of native arbuscular mycorrhizal fungi in plants growing under organic and conventional farming conditions in Oman

Although arbuscular mycorrhizal fungi (AMF) are widespread in both natural and agricultural environments, their biodiversity and community structure are not well understood. This is particularly true for the influences of different farming practices on their taxonomic distribution. This study aimed to investigate the influence of organic and conventional farming on AMF diversity in the rhizosphere soils of three crops includng mango, citrus and cucumber from Oman. Spore morphological analysis and internal transcribed spacer (ITS) sequencing were used to identify AMF species diversity. Spore morphological analysis revealed a total of 9 families, 20 genera, and 36 species, and in general, organic farming samples showed higher diversity than conventional farming samples. The ITS sequencing analysis showed the presence of 6 families and 12 genera, with organic farming samples being significantly more diverse than conventional farming samples based on the number of taxa and Shannon H index. Both spore morphology and ITS sequencing data showed that the families Diversisporaceae and Glomeraceae were the most abundant among all the treatments. Compared to their respective conventional soils, the mean percent mycorrhizal inoculum potential was significantly higher for the organic soils under cucumber, with the root colonization being also higher for organic soils under citrus. A quick colonizer trap culture method was used to determine which AMF species colonized and established in the roots after 14 days. AMF species including Rhizoglomus intraradices and Septoglomus viscosum quickly infected cucumber, and could potentially be used as biofertilizer inocula. The results help to understand the AMF diversity across different farming systems in semiarid and arid regions, as well as to promote and develop sustainable agriculture in these regions.