1. Diversity of Arbuscular Mycorrhizal Fungi in Cultivated Soils of the Canadian Prairie
C. Hamel1*, E. Furrazola Gomez2, Y. Torres-Arias2 and W. Eilers3
1 Semiarid Prairie Agricultural Research Centre, AAFC, Swift Current SK, Canada.
2 Instituto de Ecologia y Sistematica, La Havana, Cuba.
3 Land Resource, AAFC, Saskatoon, SK, Canada.
Introduction
Under the light of ecological principles, a crop plant appears as an ecosystem with a device for efficient soil nutrient extraction: the arbuscular mycorrhiza (AM).
Organic Science Cluster Project A2 aims at modeling the contribution of AM fungi to wheat nutrition in cultivated soils of the Canadian Prairie, to better use this symbiosis. Fields in the main ecozones of the Prairie were surveyed in , as a first step to describe the diversity of AM fungi living in Prairie soils, along with the soil environment where they are found. It soon appeared that the metagenomics methods used to describe AM fungal diversity would be insufficient to reveal the identity of the AM fungal species living in the Prairie landscape. The AM fungal diversity encountered in Prairie wheat fields far exceeded the information on AM fungi contained in GenBank, the collection of all publicly available DNA sequences and, consequently, the vast majority of the AM fungal sequences found in surveyed soils cannot be identified.
Objective: Document the diversity of AM fungi based on morphology, using a collection of Prairie AM fungal isolates.
Diversispora spurca
Entrophospora infrequens
Glomus geosporum
Glomus viscosum
Glomus sp.7
Material & methods
Glomus claroideum
Glomus intraradices
Glomus sp.1
Glomus sp.8
Because AM fungi only grow in association with living plant roots, trap-cultures of AM fungi were created by growing leek plants inoculated with soil from fields surveyed in 2007 (Fig. 1). Trap cultures are maintained in calcined clay with weekly application of 60 ml of ½P-Long Ashton nutrient solution.
Glomus clarum
Glomus irregulare
Glomus sp.2
Glomus sp.9
Glomus cubense
Glomus luteum
Glomus sp.3
Kuklospora kentinensis
Fig. 1 Trap cultures of AM fungi were established on leek plants with soil samples taken from cultivated fields ( ) in early June 2007 from all Prairies soil zones.
Glomus eburnum
Glomus microaggregatum
Glomus sp.4
Pacispora sp.1
Fig. 2. AM fungal spore extraction from the growth substrate of trap cultures by wet sieving and gradient centrifugation.
Glomus etunicatum
Glomus monosporum
Glomus sp.5
Pacispora sp.2
Glomus fasciculatium
Glomus mosseae
Glomus sp.6
Paraglomus occultum
Spores were collected from these trap cultures through soil sieving and gradient (60% sucrose) centrifugation (2500 rpm for 5 min) (Fig. 2). Spores were put on a Doncaster plate and picked up with a Pasteur pipette under a stereomicroscope. Morphotypes were grouped based on size, color, spore content, and general aspect. Spores morphotypes were mounted on slides with PVLG and PVLG-Melzer and observed under the compound microscope.
were Glomus irregulare, Glomus claroideum and Glomus monosporum. Other species identified were Diversispora spurca, Entrophospora infrequens, Glomus clarum, Glomus cubense, Glomus eburneum, Glomus etunicatum, Glomus fasciculatum, Glomus geosporum, Glomus intraradices, Glomus luteum, Glomus microaggregatum, Glomus mosseae, Glomus viscosum, Kuklospora kentinensis, and Paraglomus occultum. Eleven morphotypes belonging to the genera Glomus (9), and Pacispora (2) could not be identified to the species level. Interestingly, a species of Peridiospora, a genera initially thought to belong to the AM fungi, was found in one trap-culture (not shown).
Conclusion
This is one of very few reports on the diversity of AM fungi in the Canadian Prairie, and the largest. AM fungi are a tool for sustainable food production that is being discovered.
Results
Industry Partners
Two soil samples out of the 38 trap cultures examined did not produce any AM fungal growth, but 29 species where recovered from other soils (Fig. 3). The most common species encountered
Thank you to Western Ag Innovations, the Canadian Wheat Board, Growing Forward, and Agriculture and Agri-Food Canada.
Organic Cluster Winnipeg Feb © 2012