title: Early-flowering Scots pines through tissue culture for accelerating tree breeding.
abstract: Scots pine plantlets were produced via tissue culture using cotyledons excised from germinated embryos as explants. The optimum tissue culture conditions were: 1/2GDbasal medium gelled with agar-Gelrite during shoot formation and with agar during rooting, inclusion of 5.0μM benzylaminopurine (BAP) and 0.05 μM naphthaleneacetic acid (NAA) for 2 weeks for shoot induction, and repeated 2.7 μM NAA pulses of 1 week for rooting. Micropropagation success was genotype-dependent. Average multiplication rates varied among experiments from 3 to 15 shoots per embryo. The maximum shoot production from a single embryo was 35. Rooting was the most difficult phase in the propagation process. Most of the plantlets had a plagiotrophic and highly branched growth habit when growing in the greenhouse. Some individuals produced megasporangiate strobili at the age of 3 years and microsporangiate strobili with viable pollen at the age of 4 years. Early-flowering clones and the ability to conserve seedlings from which cotyledons have been cultured give new possibilities for accelerated tree breeding.
authors.affiliation: Punkaharju Research Station, The Finnish Forest Research Institute, FIN-58450, Punkaharju, Finland.
authors.forename: H M
authors.initials: HM
authors.lastname: Häggman
authors.forename: T S
authors.initials: TS
authors.lastname: Aronen
authors.forename: A M
authors.initials: AM
authors.lastname: Stomp