![]() The creation of new cultivars is still mainly empirical, and new and interesting genotypes with attractive traits are fixed by vegetative propagation. Therefore, numerous other species could be used to exploit more of the genetic resources to introduce new desired traits like disease resistance. In fact, the tea roses originate from about ten species, which is only a small part of the gene pool available for genetic improvement. Tetraploid hybrid tea roses represent most of the commercial cultivars for cut roses currently available on the market, and they still form the basis of breeding programmes. Due to these intensive interspecific hybridizations, modern cut roses are complex tetraploids for which the mode of inheritance is not exactly known. ![]() These modern roses show vigorous growth and their large flowers are borne on stiff pedicels so that they look up (Marriott 2003). A particularly interesting new group formed the tea roses obtained by crossing two of the Chinese roses with various Bourbon ( 3x & 4x) and Noisette roses ( 2x), which were then crossed with hybrid perpetual roses ( 4x) (Zlesak 2007), in which the tetraploidy originated from R. Novel rose types with new morphological traits and colours were introduced to Europe from China during the eighteenth century, from which new groups of hybrids (Bourbon roses, Portland roses, hybrid perpetual roses and tea roses) were bred (Guoliang 2003 Joyaux 2003 Marriott 2003). of the family of the Rosaceae, comprising about 180 species and thousands of cultivars (Debener and Linde 2009). The knowledge on inheritance and marker-trait associations in tetraploid cut roses will be of direct use to cut rose breeding. We used these tetraploid linkage maps to determine associations between markers, two morphological traits and powdery mildew resistance. So far, the possibility of using marker-assisted selection in breeding of tetraploid cut roses and of other species with a tetrasomic or partly tetrasomic inheritance, is still limited due to the difficulties in establishing marker-trait associations. (Theor Appl Genet 122:489–500, 2010) allowed assigning numbers to each of the linkage groups of both maps and including small linkage groups. Comparison with the integrated consensus diploid map (ICM) of Spiller et al. ![]() Two novel parental tetraploid linkage maps were constructed using markers known from literature, combined with newly generated markers. We can exclude disomic inheritance, but while our observations are more in line with a tetrasomic inheritance, we cannot exclude that there is a mixture of both inheritance modes. The possible occurrence of double reduction was studied as well. The segregation patterns of molecular markers in a tetraploid mapping population of 184 genotypes, an F 1 progeny from a cross of two heterozygous parents, were investigated for disomic and tetrasomic inheritance. Due to intensive interspecific hybridizations, modern cut roses are complex tetraploids for which the mode of inheritance is not exactly known. Tetraploid hybrid tea roses ( Rosa hybrida) represent most of the commercial cultivars of cut roses and form the basis for breeding programmes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |