Two genetic linkage maps of tetraploid roses

A tetraploid F-2 progeny segregating for resistance to black spot, grower h abit, and absence of prickles on the stem and petioles was used to construc t genetic linkage maps of rose. The F-1 of the progeny, 90-69, was created by crossing a black spot-resistant amphidiploid, 86-7, with a susceptible t etraploid, 82-1134. The F-1 was open-pollinated to obtain 115 seedlings. AF LP and SSR markers were used to eliminate seedlings produced through cross- fertilization. The remaining progeny set of 52 F-2 plants was used to study the inheritance of 675 AFLPs, one isozyme, three morphological and six SSR markers. AFLP markers were developed with three combinations of restrictio n enzymes, EcoRI/MseI, KpnI/MseI and PstI/MseI. Most of the markers appear to be in simplex or single-dose and segregated 3:1 in the progeny. One link age map was constructed for each parent using only the single-dose markers. The map of 86-7 consists of 171 markers assigned to 15 linkage groups and covering more than 902 cM of the genome. The map of 82-1134 consists of 167 markers assigned to 14 linkage groups and covering more than 682 cM of the genome. In the AFLP analysis, EcoRI/MseI generated nearly twice as many ma rkers per run than PstI/MseI. Markers developed with three restriction enzy me combinations showed a mixed distribution throughout the maps. A gene con trolling the prickles on the petiole was located at the end of linkage grou p 7 on the map of 86-7. A gene for malate dehydrogenase locus 2 was located in the middle of linkage group 4 on the map of 86-7. These first-generatio n maps provide initial tools for marker-assisted selection and gene introgr ession for the improvement of modern tetraploid roses.