Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

SEARCHING FOR INTRASPECIFIC VARIABILITY IN TUBER MELANOSPORUM AND TUBER MAGNATUM THROUGH AFLP AND MICROSATELLITE MARKERS

RUBINI A., PORCEDDU A.,TOPINI F., RICCIONI C.

Istituto di Ricerche Sul Miglioramento Genetico delle Piante Foraggere del CNR, Via Madonna Alta 130, Perugia

A.Rubini@irmgpf.pg.cnr.it

Truffles, AFLP, STMS, SSR

Truffles are ascomycetous fungi belonging to the genus Tuber that establishes symbiotic associations, ectomycorrizhae, with roots of trees and shrubs. In addition to the beneficial effects of these mycorrhizal agents on plant growth rate, some of these fungi produce edible fruitbodies marketed worldwide. Therefore, their relevant economic importance has led to search for molecular markers for a reliable typing of these species all across their life-cycle. These studies not only provided mycologists of species-specific markers for some of the most important truffle species but also shaded lights about the intraspecific variability within these species. RAPDs, SCAR and ISSR markers in fact revealed the presence of highly polymorphic species such as T.aestivum-T.uncinatum along with other truffles such as T. melanosporum and T. magnatum that did not display an appreciable molecular intraspecific variability. As highly informative diagnostic tools, AFLP and microsatellite-based analyses are therefore in progress to assess for the presence of intraspecific variability within T.melanosporum and T.magnatum according to the truffle collection sites. By this approach it is expected to get information about the population dynamic and mating system in these two species, and verify whether fungal strains can be differentiated and marketed according to their geographical provenience.

Preliminary AFLP data within T.melanosporum samples confirmed a limited genetic variability, however some truffle populations have been clearly distinguished from all the others on the basis of the different frequencies for one or few polymorphic bands.

The screening of genomic libraries enriched for (CA)_n and (GA)_n sequences allowed to isolate microsatellite-containing loci both in T.magnatum and T. melanosporum. Using primer pairs specific to nine microsatellite-containing loci, STMS (sequence-tagged microsatellite sites) studies have been carried out on 220 T.magnatum samples collected in Italy and Istria. Out of the nine loci investigated, five were highly polymorphic allowing to identify up to 15 different alleles/ locus.

STMS analysis is also in progress in T.melanosporum to complement and compare the data resulting from AFLP analysis.