Journal of the science of food and agriculture | 2019
Showing their mettle: Extraradical mycelia of arbuscular mycorrhizae form a metal filter to improve host Al tolerance and P nutrition.
Abstract
BACKGROUND\nNew evidence has shown that arbuscular mycorrhizal (AM) fungi can contribute to the aluminum (Al3+ ) tolerance of host plants growing in acidic soils with phytotoxic levels of Al3+ . The aim of this study was to investigate the role of AM fungi isolated from naturally occurring Al3+ acidic soils in conferring host tolerance to Al3+ toxicity in 3 wheat cultivars differing in Al3+ sensitivity. The experiment was conducted in a soil-less substrate (vermiculite/perlite, 2:1, v/v) using two Al3+ -tolerant genotypes and one Al3+ -sensitive wheat genotype. The wheat was colonized with a consortium of AM fungi isolated from an andisol, with or without Al3+ at a concentration of 200 μM.\n\n\nRESULTS\nThe wheat response to Al3+ 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 Al3+ accumulation in the plants. This was achieved through two mechanisms. First, the metal chelating capacity of the AM fungi was clear in some cultivars ( Tukan and Porfiado ), in which the enhanced extraradical mycelium development was able to retain Al3+ 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 GRSP CONCLUSION: These results suggest that the role of AM fungi in cultivar-specific Al3+ detoxification can be achieved by increased extraradical mycelial filters and enhanced bioavailability of the host rhizosphere P. This article is protected by copyright. All rights reserved.