Interspecific hybridization between Cyclamen persicum Mill, and C. purpurascens Mill.

Abstract

In order to introduce valuable traits from wild species of Cyclamen into C. persicum cultivars, crosses were made between C. persicum 'ReinweiB' and C. purpurascens. Crossing barriers between C persicum 'ReinweiB' and C. purpurascens were due to late-acting incompatibility reactions. Interspecific hybrids were obtained by using ovary culture. The highest number of embryos was achieved from placentas excised 21 days and 35 days after pollination and transferred to MurashigeSkoog (M.S.)-medium containing 6% sucrose and 1% agar. The hybrids showed a habit and a chromosome number intermediate between the parents. The fragrant fiowers were pale red-purple. The chromosome number in root tips was determined as 2« = 41 while in C persicum it is 2« = 48 and in C purpurascens 2n = 34. Due to the different parental chromosome sizes, chromosomes of distinct size were still observed in the hybrid. Pollen viability varied between 0.3 and 34.0%. Parents and interspecific hybrids also showed differences in the DNA content of leaf tissue. Flow cytometric analyses were useful in the early identification of hybrids.

Embryo Rescue

“…Therefore, it is crucial: (i) to test a number of different genotypes of both parental species, and (ii) to perform the reciprocal crosses, since unilateral incompatibilities have often been reported as, for example, in Cyclamen [19], Hibiscus [20] and Dianthus [18]. The recent molecular and genetic achievements in understanding embryo and endosperm development and genome interactions [21, 22] will allow more systematic selection of parental plants in the future.…”

“…However, it is extremely dependent on the species and it is not something to generalize which conditions are recommended. It should be taken into consideration whether the first days or weeks of culture are performed in the dark, as the latter was found to be beneficial for Cyclamen [14,19], Rosa [32,33] and several other species [2,30]. In some cases, photoperiods of 12-16 h resulted in success in Cuphea [24] and Cucumis [34], for example.…”

“…If one or more paternal characters can be detected, the respective plant may be considered as a hybrid plant. In the authors' hands [19], and also for other species [18], flow cytometric confirmation (see Protocol 5.5, Figure 5.3) of interspecific hybrids was found to be reliable, fast and inexpensive. However, it is only possible to use this technique if the genome sizes of the parental species are sufficiently different.…”

Efficient plant regeneration from protoplasts isolated from embryogenic suspension cultures of Cyclamen persicum Mill.

“…More recently some reports have been published, which showed that interspecific hybridization can be successful, if in vitro embryo rescue techniques are applied. Hybrid plantlets were obtained for example in the following crossing combinations: C. persicum · C. hederifolium (Ishizaka and Uematsu 1992), C. persicum · C. purpurascens (Ishizaka and Uematsu 1995;Ewald 1996) as well as C. persicum · C. graecum (Ishizaka 1996). However, in most cases the obtained hybrids were sterile and only after polyploidization they might be used in breeding programs.…”

Identification of Ploidy Level of Cyclamen rohlfsianum Plants through Flow Cytometric and Cytological Analysis of C. rohlfsianum, C. purpurascens and their Hybrid

“…Polyploids as well as diploids have been discovered in C. hederifolium (2nϭ2xϭ34, 3xϭ51, 4xϭ68), C. africanum (2nϭ2xϭ34, 4xϭ68) (Bennett and Grimshaw 1991), C. persicum (2nϭ 2xϭ48, 3xϭ72, 4xϭ96) (Legro 1959, Takamura andMiyajima 1996) and C. graecum (2nϭ4xϭ84) (Ishizaka 2003). Estimation of nuclear DNA content by FCM has been used as an effective tool for the determination of taxa or ploidy levels, the identification of hybrids in wide cross, and the analysis of polysomaty in numerous plants, including cyclamen (Ewald 1996, Kato and Mii 2000, Mishiba and Mii 2000, Mishiba et al 2000, Kato et al 2001, Takamura et al 2001, Amano et al 2007, Hayashi et al 2007a. Legro (1959) reported that C. rohlfsianum had chromosomes of 2nϭ96, the same as autotetraploid C. persicum (2nϭ4xϭ96), but he did not refer to the ploidy level of the examined plants.…”