Showing their mettle: extraradical mycelia of arbuscular mycorrhizae form a metal filter to improve host Al tolerance and P nutrition.

BACKGROUND

New evidence has shown that arbuscular mycorrhizal (AM) fungi can contribute to the aluminum (Al ) tolerance of host plants growing in acidic soils with phytotoxic levels of Al . The aim of this study was to investigate the role of AM fungi isolated from naturally occurring Al acidic soils in conferring host tolerance to Al toxicity in three wheat cultivars differing in Al sensitivity. The experiment was conducted in a soilless substrate (vermiculite/perlite, 2:1 v/v) using two Al -tolerant wheat genotypes and one Al -sensitive wheat genotype. The wheat was colonized with a consortium of AM fungi isolated from an Andisol, with or without Al at a concentration of 200 μmol L .

RESULTS

The response of wheat to Al in the medium was dependent on both the plant genotype and AM colonization. The benefits of the AM fungi to the wheat cultivars included an increased P concentration and relatively low Al accumulation in the plants. This was achieved through two mechanisms. First, the metal-chelating capacity of the AM fungi was clear in two of the cultivars ('Tukan' and 'Porfiado'), in which the enhanced extraradical mycelium development was able to retain Al in the glomalin and hyphae. Second, the increased AM-induced acid phosphatase activity in the rhizosphere of the other cultivar ('Atlas 66') increased host nutrition possibly by hyphae-mediated nutrient uptake and glomalin-related soil protein.

CONCLUSION

The results suggest that the role of AM fungi in cultivar-specific Al detoxification can be achieved by increased extraradical mycelial filters and enhanced bioavailability of P in the host rhizosphere. © 2019 Society of Chemical Industry.

© 2019 Society of Chemical Industry.