Interspecific hybrids between Lilium 'Oriental' hybrid and L. 'Asiatic' hybrid produced by embryo culture with revised media

Abstract

The effects of sugars, phytohormones and amino acids were examined on the growth of excised embryos from compatible crosses in 'Oriental' hybrids (Lilium 'Casablanca' ×L. 'Stargazer') and in 'Asiatic' hybrids (L. 'Connecticut King' ×L. 'Capri'), and also from incompatible crosses of L. 'Casablanca' × L. 'Connecticut King' and L. 'Casablanca' ×(L. auratum × L. nobilissimum ). Embryos obtained from the crosses of the 'Oriental' hybrids could grow on the medium containing more than 3 % sucrose, but not on the medium containing 3 % sucrose irrespective of the addition of phytohormones and amino acids. Similary a higher concentration of sugar was necessary to culture the 'Asiatic' hybrid embryos. The optimum sucrose concentration is considered to be 6 %, since most of embryos on media containing 9 % and 12 % sucrose formed abnormal shoots or stopped growing within two or three months of the culture. When sucrose was partially replaced by mannitol, the survival rate was similar or increased. Addition of mannitol is recommended to adjust a high osmotic pressure of medium. Cytokinins and higher concentration of auxins induced abnormal growth of embryos. Amino acids did not affect growth of embryos. The plants from the cross between an 'Oriental' hybrid and an 'Asiatic' hybrid were obtained on the medium with high osmotic pressure, and these were confirmed to be hybrids by leaf morphology, isozyme analysis and chromosome observation.