![wild rose diagram wild rose diagram](https://www.flora.dempstercountry.org/V.B.14.Rosaceae/Rosa.acic/Rosa.acic.drawing.jpg)
More than half of the wild rose species are polyploid ( Vamosi and Dickinson, 2006), ranging from 2 n=2 x=14 to 2 n=8 x=56 ( Roberts et al., 2009), with permanent sexual pentaploids such as Rosa canina exhibiting unusual asymmetric meiosis ( Lim et al., 2005 Kovarik et al., 2008). In fact, one of the major hindrances to the creation of novel rose varieties stems from such lack of allelic variation compounded by the difficulty in introgressing alleles of interest from wild diploid species due to the polyploidy barrier. chinensis cultivars during the recent processes of varietal creation. Therefore, although the genome of Rosa×hybrida is a patchy mix of several parental genomes, the origin of its genetic variation is relatively homogeneous because of the intensive backcrossing to R. chinensis alleles ( Martin et al., 2001).
![wild rose diagram wild rose diagram](https://www.scottish-country-dancing-dictionary.com/krdiagrams/wild-rose-strathspey.png)
However, despite such apparent mosaicity, the genome of modern rose varieties seems to bear the remains of a massive introgression of R. For example, Rosa gallica and other robust polyploid species lent the trait of cold hardiness, Rosa chinensis brought recurrent blooming, and Rosa foetida bestowed the yellow flower colour.
![wild rose diagram wild rose diagram](https://i.pinimg.com/originals/ef/8e/42/ef8e42b116ba2fb6f84ea5d660b68019.jpg)
Each of these species may have contributed a specific trait. The genus Rosa comprises ~200 species, among which only 8–20 species have contributed to the genetic make-up of our present cultivars, namely the complex hybrid variety Rosa× hybrida ( De Vries and Dubois, 1996 Reynders-Aloisi and Bollereau, 1996 Gudin, 2001). The ‘modern rose cultivars’ exhibit a huge variety of characteristics such as flower shape, colour, and fragrance that we now enjoy in gardens and parks. They are also in enormous demand in the perfume and cosmetic industries. They are highly popular as garden ornamental plants and cut flowers. Today, roses are one of the most commonly cultivated ornamental plants in the world. They are usually referred to as Rosa× hybrida ( Gudin, 2003). Nowadays, ~30 000–35 000 cultivated rose varieties are said to exist. The subsequent extensive hybridization amongst the Chinese, European, and Middle-Eastern roses formed the genetic basis of the ‘modern rose cultivars’ ( Raymond, 1999) ( Fig. In the 14th century, missionaries introduced Chinese roses to Europe. Spontaneous interspecific hybrids, such as Rosa× damascena, have been stabilized by vegetative propagation. The Romans, Greeks, and Persians used domesticated roses as floral ornaments and/or as medicinal plants. Wild roses were first domesticated and multiplied to use as an animal-proof fence. Roses have been cultivated since antiquity, as early as 3000 BC in China, western Asia, and northern Africa. The genus Rosa belongs to the large family of the Rosaceae. In this review, we comment on the recent development of genetic, genomic, and transcriptomic tools for roses, and then focus on recent advances that have helped unravel the molecular mechanisms underlying several rose floral traits. The molecular and genetic events that determine some of these flower characters cannot be studied using model species such as Arabidopsis thaliana, or at least only in a limited manner. The domestication processes selected several flower characters affecting floral quality, such as recurrent flowering, double flowers, petal colours, and fragrance. Domestication of roses has a long and complex history, and the rose species have been hybridized across vast geographic areas such as Europe, Asia, and the Middle East. They are widely used as garden ornamental plants, as cut flowers, and for the production of essential oils for the perfume and cosmetic industries. Roses hold high symbolic value and great cultural importance in different societies throughout human history.