Preliminary investigations on somatic embryogenesis from leaf discs of red oak (Quercus rubra L.)

Abstract

Somatic embryos were obtained from leaf discs of juvenile red oak plants. Basal inductive nutrient medium was a modified Murashige and Skoog solution enriched with 500 mg L-' casein hydrolysate, 100 mg L-' polyvinylpyrrolidone, 5.4 @4 naphthaleneacetic acid and 0.09 w benzyladenine. Embryogenesis was obtained only from leaf discs in the presence of light and increased when the adaxial surface of the explants (with midrib or main veins present) was in contact with the medium. Large variation was observed in all experiments. Recurrent embryogenesis was observed at the base of embryo clusters with callus present; conversely, embryogenic potential was rapidly lost by subculturing full calli. Maturation, germination and development of isolated somatic embryos were obtained. However, the vast majority of embryos did not have viable apical bud meristems and on only a few occasions were shoots produced.

Improved secondary embryo production in Quercus alba and Q. rubra by activated charcoal, silver thiosulphate and sucrose: influence of embryogenic explant used for subculture

“…Low conversion rates of different embryogenic systems have been ascribed to abnormal development caused by the failure of the shoot apical meristem to become organised (Stasolla and Yeung 2003). Rancillac et al (1996) noted that red oak regenerated embryos did not have a viable apical bud meristem. In the present study, improvement of embryo quality was achieved and apparently normal shoot and root apical meristems were observed to develop in somatic embryos of the two oak species.…”

“…In Q. alba, we have induced SE from leaf explants derived from young trees (Corredoira et al 2012), but the method for proliferation of embryogenic lines has not been studied in detail. In particular, in Q. rubra, induction of SE has been obtained from immature zygotic embryos (Gingas and Lineberger 1989;Vengadesan and Pijut 2009) and leaf explants of young seedlings (Rancillac et al 1996), but no clear patterns of development for repetitive embryogenesis have been described. At present, initiation of somatic embryos from material derived from young trees has been achieved (Online Resource 1).…”

Induction of somatic embryogenesis from different explants of shoot cultures derived from young Quercus alba trees

“…Great progress has been made in developing embryogenic systems for European oaks, including Q. suber and Q. robur, in which initiation of embryogenic cultures from mature trees has been achieved by use of leaf explants excised from epicormic shoots forced from branch segments (Hernández et al 2003;Toribio et al 2004), and from leaf explants and shoot apices excised from shoot cultures of Q. robur of mature origin (San-José et al 2010). Unfortunately, studies of SE in American oaks are scarce and limited to initiation of somatic embryos from immature zygotic embryos (Gingas and Lineberger 1989;Vengadesan and Pijut 2009) and leaf discs from seedlings (Rancillac et al 1996) of Q. rubra. When male catkins were used as explants, embryogenic cultures were obtained from Q. bicolor, whereas the callus formed in Q. rubra degenerated after 5 months in culture, and failed to yield embryogenic structures (Gingas 1991).…”

Somatic embryogenesis and plant regeneration of northern red oak (Quercus rubra L.)

“…Direct and indirect embryogenesis were induced from immature zygotic embryo explants using 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA), but plantlet regeneration was low (Gingas and Lineberger 1989). Leaf discs from 1.5 to 3-month-old seedlings were used as explants to induce embryos using a-naphthaleneacetic acid (NAA) and BA, but the majority of embryos did not have a viable apical bud and plantlet survival was low (Rancillac et al 1991(Rancillac et al , 1996. Callus cultures obtained from male catkins using BA or 2,4-D did not regenerate embryos in NRO (Gingas 1991).…”