The Complete Chloroplast Genome of a Key Ancestor of Modern Roses, Rosa chinensis var. spontanea, and a Comparison with Congeneric Species.

Rosa chinensis var. spontanea, an endemic and endangered plant of China, is one of the key ancestors of modern roses and a source for famous traditional Chinese medicines against female diseases, such as irregular menses and dysmenorrhea. In this study, the complete chloroplast (cp) genome of R. chinensis var. spontanea was sequenced, analyzed, and compared to congeneric species. The cp genome of R. chinensis var. spontanea is a typical quadripartite circular molecule of 156,590 bp in length, including one large single copy (LSC) region of 85,910 bp and one small single copy (SSC) region of 18,762 bp, separated by two inverted repeat (IR) regions of 25,959 bp. The GC content of the whole genome is 37.2%, while that of LSC, SSC, and IR is 42.8%, 35.2% and 31.2%, respectively. The genome encodes 129 genes, including 84 protein-coding genes (PCGs), 37 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. Seventeen genes in the IR regions were found to be duplicated. Thirty-three forward and five inverted repeats were detected in the cp genome of R. chinensis var. spontanea. The genome is rich in SSRs. In total, 85 SSRs were detected. A genome comparison revealed that IR contraction might be the reason for the relatively smaller cp genome size of R. chinensis var. spontanea compared to other congeneric species. Sequence analysis revealed that the LSC and SSC regions were more divergent than the IR regions within the genus Rosa and that a higher divergence occurred in non-coding regions than in coding regions. A phylogenetic analysis showed that the sampled species of the genus Rosa formed a monophyletic clade and that R. chinensis var. spontanea shared a more recent ancestor with R. lichiangensis of the section Synstylae than with R. odorata var. gigantea of the section Chinenses. This information will be useful for the conservation genetics of R. chinensis var. spontanea and for the phylogenetic study of the genus Rosa, and it might also facilitate the genetics and breeding of modern roses.

Simulation of climate change effect on the global distribution of Rosa multiflora.

Rosa multiflora, originated from East Asia, is one of the original ancestors of modern roses. It is also an important genetic resource and rootstock for rose cultivation. Due to its high resistance and vigorous growth, R. multiflora has become an invasive species in some introduction sites, such as North America. To explore the correlation between the suitable habitat of R. multiflora and climate change, we predicted its potential geographic distribution with an optimized MaxEnt model based on 1246 distribution records and nine bioclimatic variables. The results showed that the mean temperature of the coldest quarter, minimum temperature of the coldest month, precipitation of the warmest quarter, and isothermality were significant bioclimatic variables affecting the potential geographic distribution of R. multiflora. Under current climate conditions, R. multiflora naturally distributed in the plains and hilly areas to the east and south of the Loess Plateau. The distribution pattern in the mid-holocene was similar to its current distribution, but the highly suitable distribution area was in the south of North China Plain, the Sichuan Basin, and parts of the Middle-Lower Yangtze Plain. During the last interglacial, the suitable areas generally contrac-ted southward, while the highly suitable areas significantly expanded and mainly located in the Sichuan Basin, the Middle-Lower Yangtze Plains, the Yunnan-Guizhou Plateau, and the Southeast Hills. Beyond its natural distribution in East Asia, R. multiflora had been introduced and spread to most parts of Europe and the central and eastern United States. The distribution area of R. multiflora would expand under three warming scenarios of different shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, and SSP5-8.5) during 2041-2060 and 2081-2100. Its average distribution center (centroid) would shift towards higher latitude, indicating that the distribution of R. multiflora was closely related to climate change and that global warming might lead to an expansion of its distribution area. These results would improve our understanding of the ecological adaptability of R. multiflora, facilitate the predicting of its future distribution, and provide a theoretical basis for monitoring and early warning measures following its introduction.

[Development of new SSR markers from EST of SSH cDNA libraries on rose fragrance].

The new SSR markers of rose related fragrance were developed based on the SSH cDNA libraries of rose floral scent mutant. In this study, 10 EST-SSRs (2.6%) from 391 ESTs in the libraries were identified. Six EST-SSRs primers were designed to sequence flanking SSRs. The primer pairs designed were screened on the wild-type Jinyindao, which has flowers full of pleasant scent, and the mutant-type Wangriqinghuai without perceivable floral scent. Five primer pairs were amplified effectively in Jinyindao and Wangriqinghuai, and 3 were polymorphic between Jinyindao and Wangriqinghuai. Eighteen rose cultivars including fragrant roses and nonfragrant roses were identified by the five prime pairs. These results proved that EST-SSR markers are effective markers to identify the polymorphism of the rose.