RESUMO
Grapevine (Vitis) rootstock varieties or cultivars are used to confer resistance and tolerance to insect and disease pests, unfavorable soil conditions, and other environmental conditions to cultivars that are susceptible to these conditions but otherwise have desired properties. The need to genotype and thoroughly identify grapevine rootstock varieties in the grape industry has become increasingly critical as more and more varieties are bred or selected. Although DNA markers have advantageous applications in plant identification, markers developed from classic DNA fingerprint analysis methods are not practical for plant cultivar identification. The manual cultivar identification diagram (MCID), which was previously developed in our research group, has been shown to select DNA markers that are relatively more exploitable in identifications of genotyped plant individuals. Using this MCID strategy and expressed sequence tag-simple sequence repeat (EST-SSR) markers, we identified 22 grapevine rootstock cultivars of diverse origin. All cultivars were clearly separated by fingerprints of seven pairs of EST-SSR primers and the grapevine rootstock CID (V-R-CID) generated is both practical and referable for the identification of any grapevine rootstock cultivars studied here. Furthermore, fewer primers can be used to distinguish all cultivars using this approach since the fingerprint from each primer pair could be used several times once it is generated. This initial version of V-R-CID can be made more informative with the identification and incorporation of more cultivars, thus providing better service to the grape industry.