Two genetic linkage maps of tetraploid roses

Abstract

A tetraploid F2 progeny segregating for resistance to black spot, growth habit, and absence of prickles on the stem and petioles was used to construct genetic linkage maps of rose. The F1 of the progeny, 90–69, was created by crossing a black spot-resistant amphidiploid, 86–7, with a susceptible tetraploid, 82–1134. The F1 was open-pollinated to obtain 115 seedlings. AFLP and SSR markers were used to eliminate seedlings produced through cross-fertilization. The remaining progeny set of 52 F2 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 restriction 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 linkage 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 markers per run than PstI/MseI. Markers developed with three restriction enzyme combinations showed a mixed distribution throughout the maps. A gene controlling the prickles on the petiole was located at the end of linkage group 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-generation maps provide initial tools for marker- assisted selection and gene introgression for the improvement of modern tetraploid roses.