Molecular Phylogeny Of Genus Rosa L. And The Possible Origin Of Several Cultivars

Rosa L., distributing in the northern hemisphere ranging from temperate to subtropical region, is one of the larger genera of Rosaceae. It contains about 200 species worldwide.Since it was discovered and named, the intrasection and intersection relationship of Rosa and the divergence time of sections confused people. In this paper, two nuclear genes(ITS and ncpGS) and five chloroplast DNA fragments(rbcL、atpA-atpH、trnH-psbA、trnL-F、rpl16) were selected to study the phylogeny and divergence of genus Rosa.Meanwhile, the origin of 13 cultivars were explored. The main results were as below:1. The phylogeny of genus RosaThe molecular phylogenetic analysis showed that Rosa were monophyletic group. However, the relationship among sections of Rosa were complicated. R. sect.Chinenses DC., R.sect. Synstylae DC., R.sect.Rosa, R.sect. Cinnamomeae DC., R.sect.Carolinae Crép., R.sect.Microphyllae Crép. and R.sect.Caninae DC. were all paraphyletic groups.The Sect.Rosa, Sect.Caninae were closer to Sect.Chinenses and Sect.Synstylae allies. The Sect. Cinnamomeae and the Sect.Carolinae should be merged into one section. R.sect.Laevigatae Thory. and R.sect.Bracteatae Thory. were closer to R.sect.Banksianae Lindl., which was a monephyletic group and the R.pseudobanksiae may belong to. R.sect.Pimpinellifoliae distributing in the southwest of China, was a monophylwtic group, far away from R.kokanica and R.foetida in the same section.2. Divergence time of RosaGenus Rosa originated about 30 Mya ago with two different directions in evolution.The Sect.Cinnamomeae and Sect.Carolinae allies separated from the rest of Rosa at about 13.4 Mya ago and appeared at about 8.3 Mya ago.They splited from each other at about 2.8 to 3.1 Mya ago.. The Sect.Pimpinellifoliae distributing in the southwest of China, formed about4.0 Mya ago and separated from other groups about 10.1 Mya ago. The Sect.Banksianae, the Sect.Laevigatae, the Sect.Bracteatae and R.roxbunghii had a closer phylogenetic relationship. The Sect.Banksianae separated from others 2.2 Mya to 3.2 Mya ago. The Sect.Laevigatae and the Sect.Bracteatae separated from others 2.2 Mya to 2.3 Mya ago. The Sect.Chinenses and the Sect. Synstylae were younger sections with a history of 1.9 Mya, and they have closer phylogenetic relationship with the Sect.Caninae and the Sect.Rosa. The Sect.Caninae had a history of 2.0 Mya. The formation of Sect.Rosa remained unclear to us.The results also showed that the extant species of the genus Rosa originated 3 Mya to 4 Mya ago and there were a plurality of refuges in the glacial period. The Henduan mountain region might be one of the important refuges for them. The large number of extant species was possible the results of uplift of the Qinhai-Tibet plateau and environmental change.3. The possible origin of several cultivarsThe sect.Chinenses(R.chinensis var. spontanea, R.odorata var. odorata, R.chinensis var. semperflorens and R.odorata var. erubescens), the sect.Synstylae(R.henry, R.multiflora, R.longicuspis and R.weisiensis), the sect.Cinnamomeae(R.rugosa), the sect.Pimpinellifoliae(R.foetida, R.omeiensis), the sect.Caninae(R. Caninae, R.glauca) played an important role in the formation and development of these cultivars.The sect.Banksianae, the sect.Laevigatae, the sect.Bracteatae and the sect.Microphyllae almost did not participate in the formation of these rose varieties. While the genetic contribution of the sect.Pimpinellifoliae and the sect.Cinnamomeae to modern cultivars was very little.