Morphogenesis in dormant embryonic shoots of Picea abies: Influence of the crown and cold treatment

Abstract

Retention of the crown, a plate of homogeneously thickened collenchymatous cells at the base of the embryonic shoot of Picea abies (L.) Karst., has marked effects on the induction of adventitious buds from the needle primordia. These effects were observed on embryonic shoots of three clones which were cold‐treated at 4 ± 1°C for nil, two, four and six months; and then excised either with or without the crown, before subculturing either directly on a medium lacking plant growth regulators or after application of 125 μM benzyladenine (BA) as a 3‐h pulse. Embryonic shoots retaining the crown and treated with BA responded reproducibly better than those lacking it. This was true both for the number of shoots that produced adventitious buds and for the numbers of adventitious buds per shoot. Differentiation of as many as five adventitious buds in a single needle primordium was observed, with development occurring nearly twice as early (7 as compared with 12 weeks) in the presence as in the absence of the crown. The response decreased progressively with increasing exposure to cold treatment. A number of anatomical changes occurred during culture in vitro. After 3 to 4 weeks a band of sclerenchymatous cells commenced differentiation at the centre of the crown. In embryonic shoots without the crown, a tissue which was identified as a wound periderm formed at the excision surface. Vascular unions were observed between the tissues of the newly — formed shoots induced from the needle primordia and those of the original shoot explants.

Micropropagation of yellow cedar (Chamaecyparis nootkatensis)

“…Of the different standard media evaluated in this study, SH was the best for shoot induction. This finding is in accordance with similar work done on Pinus radiata [26], P. strobus [11], Picea abies [15], and P. glauca [27]. However, our results are contrary to those reported for Chamaecyparis obtusa [14] and Thuja occidentalis [13].…”

Regeneration in vitro of economically important crop plants in the Nordic countries

“…in which the stepwise sequence of regeneration of Norway spruce plantlets from cotyledonary needles was unequivocably demonstrated, a technique incidentally applicable also to Scot's pine, reports of whole-plant regeneration are sporadic, sometimes unclear as to whether de facto regeneration was achieved, and usually are based on the procurement of at most a few plants. Adventitious budding can now be routinely induced in a number of different types of tissue, such as resting apical and lateral buds (VON ARNOLD and ERIKSSON 1979), embryonic shoots (JANSSON and BORNMAN 1983), leaves and cotyledons JANSSON 1980, 1982;BORNMAN 1980, 1981), and embryos (VON ARNOLD and ERIKSSON 1978;VON ARNOLD 1982). Whilst regeneration of plantlings of Scot's pine and Norway spruce by IVC has been demonstrated, it should be emphasized that this is possible only from embryonic and early juvenile tissues, not from those that are adolescing or mature.…”

“…In tissue culture of conifer seedling explants, the unusually high coefficients of variation of up to 50 YO sometimes found in the induction of adventitious buds (BORNMAN 1983), reflect the enormous genetic diversity to be expected in open-pollinated species. It is essential therefore to attempt to minimize the variation by factors that are more easily under experimental control, such as the medium.…”

The influence of cytokinin pulse treatments on adventitious bud formation on vegetative buds of Picea abies

“…As trees go through the maturation process it becomes more difficult to induce adventitious buds and to regenerate plantlets. Dormant buds of Picea abies also formed adventitious buds after a BA pulse, although there were great clonal differences [11]. Similarly the rooting potential of the tested clones increased after such pretreatment although the cuttings still exhibited mature growth characteristics (Dormling, personal communicacollected from: (I) a 12-year-old hedge and (II) different clones of rooted cuttings growing in a phytotron.…”