The Polymorphism of the rDNA Region in Typing Ascocarps and Ectomycorrhizae of Truffle Species

Abstract

Methods were developed to type some of the most economically important Tuber spp. (Tuber aestivum f. uncinatum, Tuber albidum, Tuber magnatum, Tuber brumale, Tuber melanosporum) and some of their mycorrhizae by the use of molecular markers. The polymorphism of the rDNA region was investigated by polymerase chain reaction (PCR) and Southern experiments on DNA isolated from ascocarps, uninoculated host roots and mycorrhizae. Using specific primer pairs, PCR amplification of the internal transcribed spacers (ITS) and intergenic spacer (IGS) of DNA isolated from fruitbodies allowed fungus discrimination only by the length or the number of the ITS and IGS amplified fragments. These results were confirmed by Southern analysis carried out on fungus DNA restricted with EcoRI and probed with the ITS fragment of T. brumale: a specific banding pattern for each species tested was evident. The same analyses were then performed on mycorrhizal root tips and inoculated host plant roots. Each fungus-host plant interaction showed a specific pattern due to the combination of traits of the two partners. It is concluded that rDNA region is a suitable molecular marker to characterize both ascocarps and mycorrhizae of truffle species by PCR and/or Southern analysis.