IDENTIFICATION OF A CODOMINANT SCAR MARKER LINKED TO THE SEEDLESSNESSCHARACTER IN GRAPEVINE

The variety Vitis vinifera cv Sultanine presents a type of seedlessnes s in which fertilization occurs but seeds subsequently fail to develop . It has been suggested that this trait might be controlled by three c omplementary recessive genes regulated by a dominant gene named I. Bul k segregant analysis was used to search for random amplified polymorph ic DNA (RAPD) markers linked to the I gene in progeny obtained by cros sing two partially seedless genotypes. One hundred and forty decamer p rimers were screened using bulks obtained by pooling the DNA of extrem e individuals from the phenotypic distribution. We identified two RAPD markers which appeared tightly linked to I(at 0.7 and 3.5 cM respecti vely). The closest marker was used to develop a codominant SCAR (seque nce characterized amplified region), named SCC8. This latter marker ap peared of great value either to exclude from the progeny potentially s eeded individuals or to select for seedless individuals. Indeed, all t he seeded individuals of the progeny were found to be homozygous scc8( -)/scc8(-), and all the individuals homozygous SCC8(+)/SCC8(+) were se edless. Moreover, this marker was successfully applied to other natura l seedless varieties where codominance persisted. SCC8 was also used t o dissect more precisely the genetics of seedlessness. ANOVA analysis indicated that this SCAR marker accounted for at least 64.9% of the ph enotypic variation of the seed's fresh weight and for at least 78.7% o f the phenotypic variation of the seed's dry matter. These results con firmed the presence of a major gene, and also the existence of other c omplementary recessive genes, controlling the expression of seedlessne ss.