Development of diploid and triploid interspecific hybrids between Lilium longiflorum and L. concolor by ovary slice culture

Abstract

Ovary slice culture, after cut-style poUination, was used to develop interspecific hybrids between Lilium longiflorum and L. concolor. Reciprocal crosses between diploid cultivars (2n = 2x = 24) were carried out. On the days 30, 35,40 and 45th after pollination (DAP), ovaries were sliced and cultured on a modified hormone-free Murashige-Skoog (M-S) medium without NH4NO3, supplemented with 6% sucrose, 50 mg/l yeast extract and 0.25% gelrite at pH 6.3. For the L. longiflorum X L. concolor cross, ovule germination was found to be best at 30 DAP. After transfer to a M-S (half-strength) medium supplemented with 1.5% sucrose and 0.25% gelrite at pH 5.8, diploid and triploid hybrid plants were established. In contrast, ovules from the L. concolor X L. longiflorum cross did not germinate. The hybridity of the plantlets obtained was verified by karyotype and isozyme analysis. The importance ofthe ovary slice culture technique as a tool to develop new hybrids between incompatible lilly plants is discussed.Key words: Lilium spp. -cut-style pollination -interspecific hybrids -isozyme -karyotype -ovary slice culture Lilium longiflorum is one of the most popular lihes in horticulture and many breeders have attempted to raise new hybrid lilies by interspecific crosses between it and other colourful lilies (Kanoh et al. 1988) such as L. coneolor, since the flower of L. longiflorum is always white. It has not so far been possible to obtain interspecific hybrids between L. longiflorum and L. concolor in vivo.The cut-style pollination method has been developed and used in lily plants to overcome cross incompatibility Myodo 1977a, van Tuyl et al. 1991). After pollination, the ovary slice culture technique has also been successfully applied to develop hybrids in the genus Lilium by several researchers (Hayashi et al. 1986, Kanoh et al. 1988, Morimoto 1990, who suggested that this technique might enable the production of interspecific hybrids in lily plants more efficiently and easily than embryo culture.In some lily crosses, fertilization occurs but hybrid embryo growth is restricted by post-fertilization barriers. Some of these irregularities are associated with various types of abnormahty in endosperm development, and the failure of endosperm development occurs at various times after fertilization (Stout 1922, Myodo 1962, Dowrick and Brandram 1970, Asano 1982.In this study, an attempt was made to improve interspecific crosses between L. longiflorum and L. concolor by using ovary slice culture at four different times after cut-style pollination. The hybridity of the plants obtained was evaluated through karyotype and isozyme analysis. Materials and MethodsPollination method: Reciprocal crosses were made between L. longiflorum cv. Wase Teppo Yuri and L. concolor cv. Akahime Yuri from the Takii Company, Japan. In this experiment, cut-style pollination was used according to the method proposed by Asano and Myodo (1977a), and van Tuyl et al. (1991). The poUinations were carried out in a greenhouse.In vitro culture procedure: On days 30...

The origin of Darwin hybrid tulips analyzed by flow cytometry, karyotype analyses and genomic in situ hybridization

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Inducción de callos embriogénicos y formación de proembriones somáticos en Pterogyne nitens Tull "tipa colorada"

“…El efecto del 2,4-D podría estar relacionado con la inducción de la respuesta morfogenética, ya que la degradación de esta auxina es más lenta cuando los explantos se incuban en oscuridad (Arzate Fernández et al, 1998).…”

Production of interspecific hybrids between Lilium longiflorum and L. lophophorum var. linearifolium via ovule culture at early stage

“…Hitherto various techniques have been applied successfully to overcome pre-and post-fertilization of incompatibility. For example, it has been reported that prefertilization barriers can be bypassed by using methods such as the cut style technique, the grafted style method, plant growth regulator treatment, and in vitro pollination (Van Tuyl et al 1988, 1991Li and Niimi 1995;Niimi et al 1999); post-fertilization barriers can be overcome by embryo rescue techniques such as embryo culture (Okazaki et al 1994), ovule culture (Niimi et al 1996), ovules-withplacental-tissue culture (Obata et al 2000), and ovary slice culture (Kanoh et al 1988;Fernández et al 1996;Arzate-Fernández et al 1998;Chi 2002).…”