PARENT SESSION
Oral Session 15: Soil Ecology I: Mycorrhizal Communities.
Presiding: V Borowicz and X He
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 137.

Arbuscular mycorrhizal fungi community structure as determined by soil type.

BESMER, YLVA¹, KOIDE, ROGER¹, ¹ The Pennsylvania State University, University Park, PA, USA

ABSTRACT- Arbuscular mycorrhizal fungi (AMF) form a symbiosis - arbuscular mycorrhiza - with plant species of most families of angiosperms and gymnosperms. While it has been shown that AMF affect overall plant productivity and plant community structure, factors affecting AMF community structure have been little researched to date. The objective of this study, therefore, was to determine the role of soil type for AMF community structure in 10 subsistence farmers' fields in Zimbabwe, five of whom were farming on black clays and five on sandy soils. Maize roots were harvested 7 weeks after emergence and analyzed following nested PCR and T-RFLP. AMF in roots were identified either by matching T-RFLP patterns with known patterns from identified spores or through sequencing of PCR products. There was an overall high abundance of AMF in the two soil types (52 and 63 % average root length colonized in the clay and sandy soils respectively), but the AMF communities in the two soils differed significantly from each other. Fungi belonging to the family Gigasporaceae were low in abundance in clay soils (14 % of root segments on average), but they were in high abundance in the sandy soils (72 % of root segments). Clay soils, however, contained more AMF in the Acaulosporaceae and Glomaceae fungi than did sandy soils. To address the cause of these differences, a greenhouse trial was set up to examine the direct effect of soil physical properties separated from indirect effects of soil physical properties on fungal competitive ability. The results from this study will also be discussed.

Key words: Community structure, Soil type, Arbuscular mycorrhiza, T-RFLP