Evidence on the evolution of polymorphism of microsatellite markers in varieties of Vitis vinifera L.

This paper contributes a description of four mutations in microsatellite allele-length found within strains of each of the varieties known as Muscat d'Alsace, Greco di Tufo, Primitivo and Corvina veronese: the comparison of microsatellite sequences of wild and mutated strains showed in all cases an increase of one or more repeats of the core GA sequence. Whereas studies on animals reported mutations which originated in gametes, in grapevines somatic cell-mutations take place and are eventually fixed and transmitted to new individuals through vegetative propagation. The mutations detected in 1998 were found again 3 years later in seven out of eight plants. A chimeric situation was clearly noted and resolved in three of the four cases described. Considerations about the genesis of microsatellite alleles and the reliability of fingerprinting with these markers are provided.