Gametic behaviour of parthenogenetic plants of Rosa canina L. and R-hybrida L.

Following an induced parthenogenesis treatment (using gamma -ray irradiated pollen), rose plants with the chromosome structure of the maternal gamete could be obtained. Thus, tetraploid plants issued from R. canina L. (originally pentaploid) and diploid plants from R. hybrida L. (originally tetraploid) were obtained. Although the haploidized plant of R. canina revealed completely male sterile, it could be successfully used as the female parent in an hybridization program with two species used as males (R. canina, R. hybrida). The ploidy level of the resulting progenies was determined. It revealed the systematic production of female 2n gametes by the haploidized plant of R. canina. The gametic behaviour of the dihaploid R. hybrida (2x), also crossed with different species, revealed much more complex. Male fertility was generally much lower than female fertility, very variable itself. The production of male and female 2n gametes was frequent and always associated with the presence of usual reduced gametes. This complexity is discussed with respect to the genetic origin of this artificial species.