Abstract:

In the present study, leaf segments from Quercus variabilis seedlings were used as explants to induce somatic embryogenesis. The influence of carbohydrates, osmotic agents, and plant growth regulators(PGRs) on somatic embryo proliferation, maturation and germination was investigated and a protocol was developed. On the initiation medium containing 1.0 mg·l^-1 αnaphthaleneacetic acid(NAA) and 0.5 mg·L^-1 6benzylaminopurine(BA) proembryogenic masses(PEMs) were induced from leaf explants. These PEMs were cultivated on a proliferation medium for 6 weeks. The best proliferation was obtained on MS basal medium with 1 mg·L^-16 benzyladenine(BA), 0.25 mg·L^-1 NAA and 3% sucrose. Individual somatic embryos were then grown on a maturation medium. Sucrose concentrations had significant influence on embryo maturation and germination. With 5% sucrose in the media, 63.5% embryos matured and 33.8% germinated. Although abscisic acid(ABA) was in favor of somatic embryo maturation，it had no positive effect on germination. To promote germination, mature embryos were cultured on the germination medium, and treated with a low temperature. Cold treatment at 4 °C was ineffective in stimulating epicotyl and radicle formation. The rate of embryo germination reached 65.9% on the germination medium consisted of 1/2 MS basal medium with 0.5 mg·L^-1 BA and 0.25 mg·L^-1 indolebutyric acid(IBA)，and the rate of conversion was 9.4%.

Key words: Quercus variabilis, somatic embryogenesis, plant growth regulators, carbohydrates