Genetic constitution of Rosa sect. Caninae (R-canina, R-jundzillii) andsect. Gallicanae (R-gallica)

摘要

All members of Rosa section Caninae (dogroses) are polyploid with 2n = 28, 35, 42 (base number x = 7) and characterised by a unique type of meiosis. This,,Canina-meiosis" is based on the heterogamous distribution of the chromosome-sets. Since 1922, when TACKHOLM described this peculiar reproduction type, several approaches have been attempted to clarify the question wether this system is due to a hybridogenic background of this section and how the genetic constitution of this polyploid taxa can be enlightened. However, all methods failed to study the genomic structure. Research on the intraindividual variation of the nrDNA marker ITS 1 in this section revealed, that ITS can be used as a marker for a specific chromosome set in the genus Rosa and thus presents the possibility to determine the generic constitution of the genus. The tetraploid R, gallica possesses two types of chromosome sets (A, B) indicating an allopolyploid origin of this species. Type A seems to be a universal type, as it is again found in R. jundzillii (2n = 6x) and R, canina (2n = 5x). Spe B is also present in R. jundzillii, now clarifiying the hypothesis of the hybridogenic origin of R. jundzillii. R, jundzillii and R, canina share type C, presumably characterising the Canina-Type. Additionally R. canina bears two other ITS-types thus being permanent allopolyploids. These findings are reported for the first time and present a new possibility for the genomic analysis in Rosa.