SOMATIC EMBRYOGENESIS FROM IMMATURE AND MATURE ZYGOTIC EMBRYOS AND FROM COTYLEDONS AND NEEDLES OF SOMATIC PLANTLETS OF LARIX

Induction of embryonal masses was achieved from full-sib immature zygotic embryos of Larix decidua Mill., Larix x eurolepis A. Henry, and Larix X leptoeuropaea, and it was found to be affected by the developmental stage of the embryos. Furthermore, the explant response depended on a specific combination of parental trees used for production of seeds. For the first time, induction was successful in L. decidua with mature zygotic embryos. These embryos were isolated from one of the three seedlots tested and induction frequency was 5%. Mature somatic embryos of L. x leptoeuropaea expressed an initiation frequency of 83%. Cotyledons and needles of plantlets derived from somatic embryos of L. xleptoeuropaea were used as explants to induce somatic embryogenesis at a frequency of 8 and 3%, respectively. A cytokinin pretreatment seemed to enhance the frequency of induction. Mature somatic embryos were obtained from embryonal masses derived from explants of different ontogenic age. Future opportunities of research into the induction of embryonal masses from mature tree tissues are discussed.