Studies on the Interspecific and Intergeneric Hybridization in Herbage Grasses I. Effects of hybrid embryo age on callus formation and plant regeneration

화본과목초의 종.속간 잡종에 관한 연구 I. 교잡* 일령에 따른 Callus형성과 식물체재분화

A breeding program in progress at Suweon Livestock Experiment Station, RDA, involves the hybridization of italian ryegrass (Lm) and several leading forage grasses in an effort to combine the nutritive, productivity and palatability qualities of Lm with the adaptive and cold resistance qual; .les of several leading grasses. In order to study the fate of the hybridization between remotely related species, immatured hybrid embryos were cultured on media. The emasculated plants of Lm were Sikem and Tetrone. Reweille, 2n=14, of perennial ryegrass (Lp.), Forager, 2n=42, of tall fescue(Fa), First, 2n=14,of meadow fescue(Fp), Potomac, 2n=28, of orchardgrass(Dg), and Richmond, 2n=42, of timothy(Ph.p) were used as pollinators. Embryos were isolated on 4, 8, 12, 16, and 20 days after pollination and cultured them on modified Murashige and Skoog media. Calluses and plantlets have been obtained after 8 days old embryos crossing between $Lm{\times}Fa$, after 12 days embryos crossing between $Lm{\times}Lp$, Dg, and Ph.p, and after 16 days embryos crossing between $Lm{\times}Fp$. Both callus and shoot formation occurred on 6 % or less of the plated embryos of $Lm{\times}Fp$, Dg, and Ph.p. Embryoderived callus forming shoots have been obtained from 4 days old embryo crossing between $Lm{\times}Dg$ which has not successfully been done anywhere as far as we know. It means that hybrid plants of species without crossability can be obtained through the use of immatured embryo culture. Some of plated embryos developed directly shoots from embryos and the others shoot-forming callus. Cross between related species showed a high frequency of directly shoot formation from plated embryos and cross between remotely related species a high frequency of callus formation.