The identification of the Rosa S-locus provides new insights into the breeding and wild origins of continuous-flowering roses

authored by
Koji Kawamura, Yoshihiro Ueda, Shogo Matsumoto, Takanori Horibe, Shungo Otagaki, Li Wang, Guoliang Wang, Laurence Hibrand-Saint Oyant, Fabrice Foucher, Marcus Linde, Thomas Debener

This study aims to: (i) identify the Rosa S-locus controlling self-incompatibility (SI); (ii) test the genetic linkage of the S-locus with other loci controlling important ornamental traits, such as the continuous-flowering (CF) characteristic; (iii) identify the S-alleles (SC) of old Chinese CF cultivars (e.g, Old Blush, Slater's Crimson China) and examine the changes in the frequency of cultivars with Sc through the history of breeding; (iv) identify wild species carrying the Sc-alleles to infer wild origins of CF cultivars. We identified a new S-RNase (SC2) of Rosa chinensis in a contig from a genome database that has not been integrated into one of the seven chromosomes yet. Genetic mapping indicated that SC2 is allelic to the previously-identified S-RNase (SC1) in chromosome 3. Pollination experiments with half-compatible pairs of roses confirmed that they are the pistil-determinant of SI. The segregation analysis of an F1-population indicated genetic linkage between the S-locus and the floral repressor gene KSN. The non-functional allele ksn is responsible for the CF characteristic. A total of five S-alleles (SC1-5) were identified from old CF cultivars. The frequency of cultivars with SC dramatically increased after the introgression of ksn from Chinese to European cultivars and remains high (80%) in modern cultivars, suggesting that S-genotyping is helpful for effective breeding. Wild individuals carrying SC were found in Rosa multiflora (SC1), Rosa chinensis var. spontanea (SC3), and Rosa gigantea (SC2, SC4), supporting the hypothesis of hybrid origins of CF cultivars and providing a new evidence for the involvement of Rosa multiflora.

Section Molecular Plant Breeding
Institute of Plant Genetics
External Organisation(s)
Osaka Institute of Technology
Gifu International Academy of Horticulture
Gifu World Rose Garden
Nagoya University
Chubu University
Sichuan University
Jiangsu Provincial Department of Agriculture and Rural Affairs
Nanjing Agricultural University
University of Angers
Horticulture research
Publication date
Publication status
Peer reviewed
ASJC Scopus subject areas
Biotechnology, Biochemistry, Genetics, Plant Science, Horticulture
Electronic version(s) (Access: Open)