ICOM1 Abstract

ARREDONDO, FELIPE1, VIC CLAASSEN2 AND BRETT M. TYLER1. 1Department of Plant Pathology, and 2Departmant of Land, Air and Water Resources, University of California, Davis, CA95616. - Diversity of rRNA Spacer Regions among VA Mycorrhizal Fungi Revegetation of degraded soils is important in a wide variety of agricultural and wildlands management contexts. Establishment of VA mycorrhizae is critical for sustainable revegetation of degraded soils where there are harsh physical conditions and poor nutrient availability. The long term aims of this research are to characterize the genetic structures of vesicular-arbuscular mycorrhizal fungal populations and to identify the strains which are effective for revegetation of degraded soils, through the use of molecular markers. Our goal is to develop molecular markers that can be used to characterize VAM populations by direct extraction of DNA from soil. The internal transcribed spacer (ITS) and extragenic spacer (EGS) of the ribosomal DNA repeats were amplified from DNA extracted from about 100 spores each from multiple accessions of Glomus intraradices, a common species in dry areas. We are presently assessing the variability of these regions at the inter-generic level down to the intra-species level in order to determine their usefulness for characterizing DNA molecules obtained directly from soil. In a parallel project we are refining techniques for extracting and amplifying VAM fungal DNA directly from unfractionated soil, and are estimating the limits of detection of this assay in field and greenhouse soils.