Genotypic control of high-frequency adventitious shoot regeneration via somatic organogenesis in loblolly pine

Mature zygotic embryos of 24 genotypes of loblolly pine (Pines taeda L.) we re used as explants to establish an adventitious shoot regeneration system through somatic organogenesis. Callus formation frequencies of 18.2 (genoty pe 11-1103) -77.7% (genotype 7-100) have been induced from mature zygotic e mbryos of all genotypes tested on callus induction medium (basal salts) con taining 2,4-dichlorophenoxyacetic acid (2,4-D) or x-naphthaleneacetic acid (NAA), 6-benzyladenine (BA), and kinetin. Adventitious shoot regeneration v ia organogenesis with the frequency of 5.4 (genotype 11-1103 and 7-2) -77.2 % (genotype 8-1082) was obtained from callus and tissue cultures derived fr om mature zygotic embryos of 24 genotypes of loblolly pine. The highest mea n number of IS adventitious buds per piece of callus 0.5 x 0.5 cm(2) in siz e was obtained from genotype 8-1082. Elongation of adventitious buds was ac hieved on TE medium supplemented with 0.5 mg; 1 indole-3-butyric acid (IBA) and 1 mg/l BA. After rooting, regenerated plantlets were established in so il. These results suggested that adventitious shoot regeneration via somati c organogenesis was influenced by the genotypes. The in vitro regeneration procedure established in this investigation could be used for clonal microp ropagation of some genotypes of loblolly pine, as well as for establishing a transformation system in coniferous species. (C) 2001 Elsevier Science Ir eland Ltd. All rights reserved.