Callus Production and Somatic Embryogenesis from White Ash

Abstract

Abstract Nonstratified white ash (Fraxinus americana L.) seeds, with one-third or one-half of their length excised, germinated 100% in vitro compared to 0% for noncut seeds on Driver and Kuniyuki walnut (DKW) medium with no plant growth regulators. Explants, therefore, consisted of one-third or one-half of the seeds containing the embryonic axis with portions of the cotyledons. More callus formed on the cut end of the cotyledons on media with 1 μΜ than 10 μΜ 2,4-D. More callus and somatic embryos formed on seedlings that remained on primary medium for 4 weeks with 5 μM BA and 2,4-D than when BA was not present. The most embryogenesis was observed on seedlings on secondary media with Murashige and Skoog (MS) nutrients and BA and NAA, both at 0.5 μΜ, or DKW nutrients with no plant growth regulators. Both direct and indirect embryogenesis were observed. Somatic embryos were quite variable; some had up to five cotyledons. Only a few embryos developed into small plantlets. The embryogenic ability of the callus lines persisted during several months of subcultures. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine (benzyladenine, BA); (2,4-dichlorophenoxy)acetic acid (2,4-D); (lαβ,4abβ,10β)-2G4a,7-trihydroxy-1-methyl-8-methylegibb-3-ene,1,10-dicarboxylic acid 1,4a-lactone (GA3, GA4+7); 1H-indole-3-butanoic acid (IBA); 1-naphthaleneacetic acid NAA).