Interspecific hybrids production between Lilium brownii var. colchesteri and its close relatives by ovary slice culture

Lilium brownii var. colchesteri (BRO) has a unique trait in its flower color. The color at anthesis is yellowish cream, and changes to white after one day. To introduce this trait and establish a sexually reproductive cultivation system for cut flower production in Lilium, interspecific crosses of L. × formolongi, L. formosanum, L. longiflorum (as seed parents) and BRO (as a pollen parent) were carried out. Capsules with unviable seeds were found in all crosses. To overcome the incongruity barrier, ovary slices excised from developing ovaries at 7 to 28 days after pollination (DAP) were cultured in Murashige and Skoog medium supplemented with 40 g·L^-1 sucrose, 40 g·L^-1 D-mannitol and 2.5 g·L^-1 gellan gum under 24 h illumination. Hybrid plantlets were obtained from crosses of L. × formolongi × BRO and L. formosanum × BRO, but not from the cross of L. longiflorum × BRO. After acclimatization, 79 (44.1%) of 179 hybrid plants produced flowers within a year of cultivation. The hybrids developed flowers changing from yellowish cream to white during anthesis as does the pollen parent. Twentyeight of 79 flowered plants sprouted two or more flower stalks, characteristics of L. formosanum. The hybrids exhibited relatively high pollen fertility and produced capsules, but no mature seed was obtained by selfpollination.