In vitro propagation of loblolly pine via direct somatic organogenesis from mature cotyledons and hypocotyls
2001
Tang, W. | Guo, Z.
A high-efficiency two-step culture procedure for direct somatic organogenesis in loblolly pine (Pinus taeda L.) resulting in the formation of multiple shoot structures induced on cotyledons and hypocotyls of mature zygotic embryos is described. Mature zygotic embryos of eight genotypes of loblolly pine were used as explants to induce direct somatic organogenesis with this two-step culture method, involving the induction and the differentiation of direct adventitious shoots. After mature zygotic embryos of eight genotypes of loblolly pine were cultured on induction medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) or alpha-naphthaleneacetic acid (NAA), 6-benzyladenine (BA), and kinetin for 2-3 weeks, embryos were transferred to differentiation medium. Adventitious shoot regeneration via direct somatic organogenesis with the frequency of 8.7-27.8% was obtained from mature zygotic embryo cultures of the genotypes tested. The highest mean number of 32.6 adventitious shoots per mature zygotic embryo was produced from genotype La. The tissue culture protocol of in vitro shoot regeneration via direct somatic embryogenesis was optimized after examining the periods of the induction culture, chilling treatment, glutamine concentration, and basic medium levels. Rooting was achieved on TE medium supplemented with 0.5 mg/l indole-3-butyric acid (IBA), 0.5 mg/l gibberellic acid (GA3), and 1 mg/l 6-benzyladenine (BA), and regenerated plantlets were established in soil. These results suggested that adventitious shoot regeneration via direct somatic organogenesis could be useful for clonal micropropagation of some genotypes of loblolly pine and for establishing a transformation system of this coniferous species.
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