The rose has a long history of use in China. As early as the Han Dynasty, there were written records of its use in China, and during the Tang and Song Dynasties, continuous flowering rose varieties were developed. The edible rose industry has flourished since the founding of the PRC, especially since the reform and opening up of the country, with a number of major edible rose producing areas in Shandong, Gansu and Yunnan; Yunnan has formed an edible rose industry with 'flower cake' as the main product, with the output value of flower cake exceeding 2 billion yuan in 2017 and a cultivation scale of about 60,000 mu. The main edible roses planted in China are 'Rosa rugosa 'Plena'', 'Purple Rose', 'Rose of Plenty', 'Ink Red Rose', 'Rose of the Sea', 'Rose of the Sea' and 'Rose of the Sea'. 'Ink-red rose', 'Dian-red rose', 'Bajie rose', 'Bitter water rose', 'Tuan-wei rose', 'Tuan-wei rose 'Tawny Rose', 'Golden Border Rose', 'Rosa × damascena' and 'Thousand Leaf Rose' (Rosa × centif) On 9 March 2010, the National Food Safety Standards and Monitoring and Assessment Department specified that 'heavy red roses' could be produced and operated as a general food resource. However, edible rose varieties vary in form from place to place, and most have unclear relationships with wild roses (Rosa rugosa L.) and 'red rose with heavy petals', and their origins are ambiguous, which largely limits the standard development of the edible rose industry, poses potential food safety risks, and is not conducive to variety improvement. At the same time, with the exception of the Pingyin rose, which is mainly produced in Shandong, most of them do not have their own variety rights and hardly have a continuous flowering habit, which seriously affects the sustainable development of China's edible rose industry.
The research group on 'Molecular Plant Genetics and Adaptation' at the Kunming Institute of Botany, Chinese Academy of Sciences (KIB) has been working on the diversity, mechanism and evolution of plant flowering habits and plant-environment interactions. The group has constructed a high quality genome at the chromosome level of 'Roses without thorns' (Zhong et al. 2021 National Science Review), analyzed the genetic regulation mechanism of moon season prickles, and proposed the hypothesis that the prickles have water storage function in early development. This has laid the foundation for research on the biology of the moon and the cultivation of new germplasm. To address the problem of unclear genetic relationships and the lack of independent varieties of Chinese cultivated edible roses, the group collected 16 domestic cultivated edible rose strains and constructed the most stable plastid genome system tree covering all major taxa of the genus Rosaceae to date by reconstructing the chloroplast genome and typing the ITS1/2 sequences of the ribosomal rDNA gene region ( "To the best of my knowledge, this is the first time I see a study that integrates as many whole chloroplast genome sequences to build a phylogenetic study in Rosa"), tracing the genetic relationships between Chinese edible rose germplasm and its possible wild relatives.
The results suggest that six wild species may have been involved in the formation of the germplasm of Chinese staple edible roses as parent species. Rosa moschata Herrm. is a tetraploid variety of 'Thousand Leaf Rose', 'Damask', 'Ruo Shui Ming' and a triploid variety of 'Jinbian Rose' is the common maternal ancestor of the tetraploid varieties 'YN01' and 'YN02' and 'Shangshui Rose' and 'Dingtao Rose', all of which are tetraploids, and the ancient Chinese moonflower YN01, YN02 and 'Shangshui Rose' and 'Dingtao Rose' are tetraploids and share a common maternal ancestor with 'Rosa chinensis 'Old Blush' (Rosa chinensis var. spontanea (Rehder & E. Wilson) T. spontanea), a single-petaled moonflower. H. Wilson) T.T. Yu & T.C. Ku). 'Ink Red Rose' is the same as 'Flowering Butterfly' (Rosa chinensis f. mutabilis (Correvon) Rehder) or 'Glandular Calyx Perfume Moon', which have the same chloroplast genome sequence. Rosa odorata 'Glandular Sepal' shares a maternal ancestor. The maternal ancestor of 'Tawny Rose' is the French rose (Rosa gallica L.). 'Heavy red rose', 'Purple branch rose', 'Plenty of flowers rose', 'Miaofeng mountain rose' and 'Fruit Rose' have a common maternal wild ancestor as a wild rose native to China. The maternal ancestor of 'Bitter Water Rose' is different from all other edible roses and is self-contained.
Fine typing studies based on the ribosomal rDNA region ITS1/2 revealed that at least nine wild species were involved in the formation of the existing main cultivars of edible roses, with wild rose, 'Rosa damascena' and French rose being the main contributors involved in the formation of several edible rose varieties. Wild roses were involved in the formation of all diploid edible rose varieties and 'Rosa tantalis', while no ITS contributions from wild roses were found for the other 'Damascus'-related varieties.
The team also found that, among the existing main germplasm, only 'Jinbian Rose' and 'Ink Red Rose' have a continuous flowering habit, while YN01, YN02, 'Shangshui Rose', ' YN01, YN02, 'Shang Shui Rose', 'Ding Tao Rose' and 'Purple Rose' have an occasional secondary flowering habit, while the other species are all primary flowering varieties. The existing varieties of edible roses that can flower continuously or occasionally secondarily are all related to the old Chinese moonflower that flowers continuously. This study will provide important basic data for the safety assessment, selection and use of edible rose germplasm, and variety improvement. The team's method of successfully assembling sample ITS sequence haplotypes using second generation data will also provide important technical support for the proper application of ITS sequences in parental tracing and phylogeny, and the related technology has been patented (202110640825.X).
The research results were published online in Horticulture Research, a leading horticultural journal, under the title "Complex and reticulate origin of edible roses (Rosa, Rosaceae) in China".
