Speaker
Description
Background and objectives
Enhancing arbuscular mycorrhizal (AM) symbiosis in crops appears as a promising way to increase agricultural sustainability, as AM fungi can aid their host plants in nutrient uptake and protect them from pathogens and environmental stresses. Simultaneously, crop domestication and breeding have produced less AM-responsive crop varieties, which may only benefit from AM symbiosis under nutrient-limited conditions. We tested in a field experiment whether the breeding effect on barley symbiosis is modulated by agricultural management through its associated differences in soil properties and AM community structure.
Methods
We compared AM colonization and community structure in roots of 13 barley varieties, released in different years and grown under organic and conventional field management. We also compared the ecological niche characteristics of AM fungal communities and the proportion of cultured and non-cultured AM taxa. In a complementary experiment using the same barley varieties, we evaluated root traits under contrasting soil management regimes.
Results
We found that the percentage of root length with arbuscules and the proportion of non-cultured AM taxa in barley roots were higher under organic than conventional management in old barley varieties, whereas these differences were absent or smaller in new varieties. Under organic management, community-weighted mean phosphorus niche optimum, phosphorus niche volume, and pH niche volume were lower and differed more strongly from conventional management in old than in new barley varieties. In the complementary experiment, old but not new varieties adjusted their root traits according to soil management, exhibiting higher specific root length and specific root area in high-fertility conventional soil than in low-fertility organic soil.
Together, these results suggest that old barley varieties adjust their nutrient acquisition strategy according to soil fertility, investing in root-mediated nutrient uptake in fertile soils and mycorrhiza-mediated nutrient uptake in nutrient-poor soils, whereas new varieties show little evidence of such plasticity.
Keywords: arbuscular mycorrhiza, Glomeromycota, crop breeding, barley, Hordeum vulgare
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