Gene expression studies in different genotypes of an ectomycorrhizal fungus require a 1 high number of reliable reference genes. 2 3

Abstract

Abstract 13 Quantitative reverse transcription PCR (qRT-PCR) has become the standard technique for the 14 expression analysis of a set of chosen genes of interest. The accuracy and reliability of qRT-15 PCR measurements strongly depends on the normalization with appropriate endogenous 16 reference genes. In this study a set of candidate reference genes for the use in gene expression 17 studies of a basidiomycete fungus, Suillus luteus, exposed to toxic concentrations of zinc or 18 cadmium was identified, evaluated and validated. Seven candidate genes were selected from 19 cDNA-AFLP as stably expressed and the algorithms geNorm and Normfinder were used to 20 evaluate these genes alongside the traditionally used housekeeping genes (actin, tubulin) in 21 different S. luteus isolates. The use of several S. luteus isolates revealed that each isolate has 22 its own most stably expressed set of reference genes, regardless of the metal treatments, i