Euphytica, 133: 65-69 (2003)
Evidence for the production of unreduced gametes by tetraploid Rosa hybrida L.
L. Crespel & S. Guden

Dihaploid roses, parthenogenetically derived from Rosa hybrida L. tetraploid cultivars, were recently shown to produce unreduced male and female gametes. On the occasion of an attempt to obtain new dihaploids, the gametic behaviour of some tetraploid R. hybrida cultivars used in the haploidization program was studied, as some deriving varieties unexpectidely revealed tetraploid. The pollen grain sizes of the original tetraploid cultivars were measured and a cytological analysis of the male meiosis was carried out. And AFLP analysis of these cultivars and their derived tetraploid varieties was made. It was used to determine the genomic contribution of the original cultivars in their derived forms. The results obtained tend to demonstrate that unreduced gametes can be produced by tetraploid roses. Perspectives for the use of such 4x gamete producing roses are discussed, as well as the adaptative value of such high leveled ploidy gametes.