CHARACTERIZATION OF GENETIC BIODIVERSITY WITH VITIS-VINIFERA L SANGIOVESE AND COLORINO GENOTYPES BY AFLP AND ISTR DNA MARKER TECHNOLOGY

A comparison between two recently developed, PCR-based DNA marker tech nologies (amplified fragment length polymorphism, AFLP; inverse sequen ce-lagged repeat analysis, ISTR) was carried out in a group of 19 Viti s vinifera L. accessions, including 13 putative Sangiovese-related gra pevines and 6 ''coloured'' ecotypes whose fruits are of importance for conferring intense red colour to the wine. A large amount of polymorp hic DNA fragments was revealed by both molecular techniques: 8 differe nt AFLP and 5 ISTR primer combinations generated 264 and 249 polymorph ic markers, respectively. Similarity relationships among the accession s were described by cluster analysis. The AFLP analysis revealed the e xistence of a uniform group for the Sangiovese (SG) ecotypes showing a high degree of genetic relatedness for the members of this cultivar. Among the coloured ecotypes (CLR), variability was more evident. Only the so called Colorino americano ecotype significantly diverged from b oth groups. ISTR analysis confirmed the genetic dissimilarity of Color ino americano and the existence of the SG and CLR groups, but in addit ion detected a higher proportion of polymorphism among the Sangiovese accessions compared to AFLP analysis. Sangiovese forte and Saragiolo a pparently differed from the other SG-related grapevines in agreement w ith AFLP results. It is possible that the observed genetic dissimilari ty between Sangiovese forte, Saragiolo and other SG-related types coul d be interpreted by the putative polyclonal origin of many grapevine c ultivars, a concept which is generally accepted by the grapevine resea rch community. Both AFLP and ISTR appear to represent innovative, effi cient and sensitive molecular tools for investigating genetic diversit y among Vitis vinifera ecotypes and for the eventual identification of clones.