Abstract
Interspecific crosses were made between a sterile species (L. incarnata) and four fertile species (L. sanguinea, L. sprengeri, L. radiata var. pumila (L. pumila, hereafter), and L. aurea) to breed varieties with new characters. Embryos, excised from ovules 20-30 days after pollination, were cultured on a modified MS medium containing 500 mg·liter-1 casein hydrolysate (Ma et al., 2001). Interspecific crosses using L. incarnata as a female parent yielded 26 hybrid plants, whereas that of L. sanguinea × L. incarnata produced none. Cytological studies revealed that all hybrids were triploid, which would have originated from the fertilization of an unreduced 2n-egg of the female parent (L. incarnata) and a normal haploid gamete of the male parent. The hybridity was also confirmed by isozyme analysis in 26 hybrid plants and partly by character observation in hybrid plants of L. incarnata × L. pumila.
