Unraveling the distribution of AMF communities and their metabolites associated with soils of minor millets

Abstract

Arbuscular Mycorrhizal Fungal (AMF) diversity in three different soil types and five different crop types of minor millets growing regions of Tamil Nadu, India was assessed. 24 species belonging to 11 genera namely Glomus, Gigaspora, Claroideoglomus, Rhizophagus, Funneliformis, Paraglomus, Entrophosphora, Acaulospora, Ambispora, Septoglomus and Scutellospora were reported for the first time in minor millet ecosystem exhibiting the richness of AMF. Glomus fascicultum, Rhizophagus intraradices and Funneliformis mosseae were most commonly present species with high relative abundance in both soil and crop types of minor millets. Comparatively, the soil types recorded higher species richness and isolation frequency than crop types. However, the species Acaulospora scrobiculata, Glomus hoi, Entrophosphora sp., Entrophosphora infrequens and Scutellospora erythropha were not recorded in soil types, whereas all the 24 species were observed in crop types. Interestingly, the species Acaulospora scrobiculata was found only in the soils of foxtail millet among the crops and soil types observed. Diversity indices viz., Shannon (1.46 ± 0.02 to 2.00 ± 0.03), Simpson (0.76 ± 0.01 to 0.85 ± 0.02) and species evenness (0.66 ± 0.01 to 0.77 ± 0.01) showed significant variation among soil and crop types. Principal component analysis of soil physico-chemical properties on AMF diversity revealed N, P and K contents had a positive influence on spore density, total glomalin content, species richness, Simpson and Shannon index in both soils and crop types. In contrast, soil pH, EC and organic carbon indicated a negative influence in soil type and positively influenced on crop types. Pearson coefficient results confirmed that soil available P content positively correlated with spore density (R2 = 0.92) and total glomalin (R2 = 0.90) content in minor millets. Further 50 to 90 per cent root colonization and increased plant growth parameters were observed in all the 24 species. Mycorrhizal associated root metabolites revealed that a total of 117 compound with 26 different groups encompassing predominant group namely Alkane, fatty acyls, hydrocarbon, Fatty alcohols, Fatty acids and carboxylic acid which conferred the multifunctional role of AMF towards management of biotic and abiotic stresses. Among the spores, Glomus fascicultum reported 46% compounds followed by Rhizophagus intraradices (34%) and Funneliformis mosseae (23%) over non mycorrhizal roots.