Arbuscular mycorrhizal fungi in a mountain grassland II: Seasonal variation of colonization studied, along with its relation to grazing and metabolic host type

Abstract

The relationships among seasons, host metabolic type, grazing and arbuscular mycorrhizal colonization were analyzed in a high South American native grassland. This study investigated seasonal changes and grazing effects on the symbiotic endomycorrhizal interaction in 5 Poaceae [C₃ metabolic pathway: Briza subaristata Lam., Deyeuxia hieronymi (Hack.) Türpe and Poa stuckertii (Hack.) Parodi; with C₄ metabolic pathway: Eragrostis lugens Nees and Sorghastrum pellitum (Hack.) Parodi; and a Rosaceae (Alchemilla pinnata Ruíz & Pav.)]. All hosts were dominant species in the mountain grassland in central Argentina. It was found that the seasons markedly influenced endomycorrhizal colonization, whereas grazing did not affect this interaction. C₄ grasses presented the highest root colonization. Hosts Briza subaristata (C₃ metabolic pathway) and Sorghastrum pellitum (C₄ metabolic pathway) showed Arum- and Paris-type colonization and intermediate forms.

• AMF
• endomycorrhiza
• grasses
• grazing
• mountain grassland
• plant metabolic pathway
• seasonality

We thank M. Cabido and S. Díaz for their experimental-design suggestions; A. Anton and L. Domínguez for their direction; and N. Tedesco for critical review of the manuscript. We are deeply grateful to L. Galetto and C. Urselay for their help with statistical analysis. The senior author received financial support and a fellowship from CONICET (Argentinean Council of Science and Technology Research) for this study.