Somatic embryogenesis in Sitka spruce (Picea sitchensis (Bong.) Carr.)

Embryonal-suspensor masses from immature embryos from cones of Sitka spruce (Picea sitchensis (Bong.) Carr.) proliferated on a modified Murashige & Skoog medium with N⁶-benzyl-aminopurine, kinetin, 2,4-dichlorophenoxyacetic acid and an organic nitrogen source. The slimy white embryonal-suspensor masses with proembryos were maintained on a solid proliferation medium with reduced amounts of growth regulators. Transfer of embryonal-suspensor masses to a non-woven polyester carrier with liquid maturation media containing ±2-cis-4-trans-abscisic acid and a reduced amount of inositol and organic nitrogen resulted in synchronized embryo formation. Further development was achieved on a medium without ±2-cis-4-trans-abscisic acid and organic nitrogen. Somatic embryos were successfully transferred ex vitrum.Abbreviations ABA ±2-cis-4-trans-abscisic acid - BAP N⁶-benzyl-aminopurine - ESM embryonal-suspensor masses - KIN kinetin - 2,4-D 2,4-dichlorophenoxyacetic acid     

Diurnal water storage in the stems of Picea sitchensis (Bong.) Carr.

Abstract. Two models of the relationship between diurnal variation in shoot water potential and transpiration in 14-year-old Picea sitchensis (Bong.) Carr. were compared. The first model was a physiologically based resistance-capacitance (R-C) analogue with its associated differential equations. The second was a non-physiological discrete-difference (D-D) or stochastic transfer function model. The RC model included only the effect of water storage in the phloem and bark while the D-D model implicity included all storage mechanisms. The R-C and D-D models explained similar fractions (62% and 68% respectively) of the variation in shoot water potential due to diurnal changes in transpiration rate. However, the D-D model had fewer parameters than the R-C model. The results from the D-D model showed that the resistance to flow from soil to shoots along the trunk, (RT), was 5 × 10³ MPa kg^-1s and the capacitance of the phloem and bark treated as a single store, (C_s), was 1.6 kg MPa^-1. It is suggested that the resistance to flow into storage (R_s) is much greater than R_T and can be disregarded. A non-linear version of the D-D model suggested [hat resistance to flow in the trunk increases with increasing transpiration rate.     

Localised impact of Sitka spruce (Picea sitchensis (Bong.) Carr.) on soil permeability

A typical upland soil catena afforested with Sitka spruce (Picea sitchensis (Bong.) Carr.) was chosen to examine the localised effect of trees on soil permeability. A borehole permeameter was used to measure soil permeability at 0.2 m and approximately 2 m distance from the stem of 20 trees at a fixed measurement depth of 0.25 to 0.45 m. In the case of the near-tree measurements, this corresponded to soil beneath the main root plate of each conifer. Two principal elements of the soil catena: the ferric podzol of the mid-slope and histosol soil of the foot-slope were investigated.The preliminary data set shows that within the ferric podzol element, the permeability of the soil beneath individual conifers was a factor of 5.4 less than that of the adjacent soil. In contrast, within the histosol sub-tree permeabilities could not be distinguished from those of soil 2 m away from each tree. The decrease in sub-tree permeability within the podzol may be caused by sensitivity of the Bsl horizon to consolidation by tree weight or by enhanced illuviation resulting from changes in local soil chemistry. The histosol may be less sensitive to such processes. The results of a consolidation test applied to the Rawls and Brakensiek model of soil permeability supported the possible role of consolidation in the reduction of soil permeability beneath conifers in podzolic soil. Additional data on soil bulk density, porosity and texture are required to corroborate either the consolidation or illuviation hypotheses. As the Bsl horizon of ferric podzol soil is typically slowly permeable, a further decline may (i) restrict root development and thus, increase windthrow hazard, and (ii) increase the lateral flow of water within podzolic Eag horizons and thus affect stream acidification. Deep ploughing of a site prior to afforestation may mitigate such impacts.     

Intraspecific variation of DNA per cell between Picea sitchensis (Bong.) Carr. provenances

Quantitative intraspecific variation of DNA per cell was established by means of biochemical, double wavelength microspectrophotometry and micro-densitometric analyses of root tips from 7 seed sources of Picea sitchensis (Bong.) Carr. Northern seed sources possessed more DNA per cell than southern provenances. This, perhaps, is an indication of DNA adaptability through plasticity resulting from changing environmental stress over the natural range.     

The Induction of Root Dormancy in Picea sitchensis (Bong.) Carr. by Abscisic Acid

Abscisic acid at 10⁴ M inhibited elongation and induced dormancyin roots of Sitka spruce cuttings growing in solution culture.The dormancy was characterized by superficial browning whichprogressed towards the root tip and by the development of alayer of lignified and suberized cells around the root apex.The dormant roots remained alive and resumed growth on transferto ABA-free solutions. The induction of dormancy was confinedto those roots actually bathed in the ABA solution and a rangeof conditions which affected shoot activity did not alter theresponse. By contrast, the time for which the roots had beenelongating strongly influenced root dormancy since it was notinduced in roots which had recently begun to elongate in solutionculture. The possible role of ABA in inducing root dormancyunder adverse conditions is discussed.     

Effect of carbenicillin and cefotaxime on somatic embryogenesis of Sitka spruce (Picea sitchensis (Bong.) Carr.)

Carbenicillin prevented the development of mature somatic embryos,reduced early stage embryos by >90% and tissue growth by50%. Cefotaxime had no effect on overall tissue growth, butreduced the development of early and mature embryos by 20% and66–80%, respectively. Carbenicillin should not be usedfor transformation of Sitka spruce. Key words: Sitka spruce, somatic embryogenesis, antibiotic sensitivity     

Ectomycorrhizal types and endobacteria associated with ectomycorrhizas of Morchella elata (Fr.) Boudier with Picea abies (L.) Karst

Subterranean morel sclerotia connected with ascomata of Morchella elata (Fr.) Boudier were found to surround 155 ectomycorrhizal root tips of Picea abies (L.) Karst, belonging to seven different types. Based upon anatomical and cytological studies, three ectomycorrhizal types could be attributed to types already described, whereas four types appeared to be undescribed. The nature of the association between the morel and the mycorrhizal types was dependent on the type and was not related to their vitality. In particular, morel ectomycorrhizas formed secondarily and exclusively by succeeding to primary mycorrhizas of a heterobasidiomycete. In addition to this triple association, an endobacterium was observed growing within the Hartig net of this heterobasidiomycete mycorrhiza. The significance of this complex of associations for the formation of ectomycorrhizas by the morel is discussed.     

Characterization of Picea abies (L.) Karst. ectomycorrhizas: discrepancy between classification according to macroscopic versus microscopic features

Summary In a 3-year study of ectomycorrhizal diversity in 2 Norway spruce stands in Switzerland the macroscopically classified ectomycorrhizal types were analyzed microscopically to compare the results of the 2 approaches. A total of 22 ectomycorrhizal types were macroscopically classified in the 2 stands. Microscopic investigations — particularly of mantle structures — resulted in the identification of 7 additional types to give a total of 29. These additional types resulted from separation of macroscopically identical types occurring on both stands (type-pairs) at the microscopic level. The problematic nature of characterization and classification of ectomycorrhizas is discussed.     

Abrasive damage by wind to the needle surfaces of Picea sitchensis (Bong.) Carr. and Pinus sylvestris L.

Abstract. After a period of one week at 11m s⁻¹ in a wind tunnel, the leaf surface of Picea sitchensis and Pinus sylvestris had undergone structural modification. Low-temperature scanning electron microscopy was used to examine these changes. Picea showed flattening and smearing of wax crystals, as well as cracks in some of the wax structures filling the stomatal antechambers. In Pinus , most damage was on the cells surrounding the stomatal antechamber or on needle ridges. Artificially abraded surfaces were of similar appearance. Minimum epidermal conductance to water vapour ( g _e^MIN) was determined gravimetrically. In Picea g _c^MIN was more than doubled by wind treatment and increased eightfold by rubbing. Similar but less extreme increases occurred in Pinus. Neither species showed recovery of g _e^MIN after 1 week at low windspeed.     

Development of a set of highly polymorphic genomic microsatellites (gSSRs) in Sitka spruce (Picea sitchensis (Bong.) Carr.)

Robust, polymorphic microsatellite DNA markers (simple sequence repeats—SSRs) are valuable tools for a range of tree conservation and breeding applications. SSRs are routinely used in the study of population genetic structure and diversity, pedigree reconstruction and genetic linkage mapping. Their abundance in the genome, co-dominant inheritance and potential for cross-species amplification make microsatellites highly prized markers. This paper characterises 22 novel genomic polymorphic microsatellite loci for Sitka spruce (Picea sitchensis (Bong.) Carr.). Amplification of DNA from Sitka spruce material was carried out both with a set of unrelated trees to obtain diversity statistics for each locus, and with the progeny of a full-sib family to test simple Mendelian inheritance. Observed heterozygosity ranged from 0.38 to 0.91 and allele number per locus ranged from 6 to 21, with a mean of 12.2. In addition, the primer pairs were tested with DNA from Norway spruce (P. abies) and white spruce (P. glauca) to investigate their potential for cross-species amplification and ten loci amplified in all three species. The results from these genomic microsatellites are compared to data generated from microsatellites derived from Picea EST libraries. In summary, this novel, highly polymorphic markers represent a significant addition to the rapidly expanding Picea genomics tool-box. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The effect of applied heat on graft union formation in dormant Picea sitchensis (Bong.) Carr

The effect of application of heat on the development of graftunions in dormant Picea sitchensis (Bong.) Carr (Sitka spruce)was observed at monthly intervals from October to March. Noadvantage over controls was gained in terms of final graft successrates. It is suggested that this may have been a result of themild winter conditions during the course of the experiment,which enabled callus formation to occur in unheated controls.On the other hand, scions of grafts which had been heated for3 weeks, and then returned to ambient conditions showed considerablygreater growth than unheated controls during the following springand summer. The amount of extension depended on how late inthe winter the graft had been prepared and heated, with leastgrowth by grafts made in October, and most by grafts made inMarch. Microscopical examination showed that callus formationwas more rapid in heated grafts than in controls, although callusformation occurred in all control grafts examined. Heat alsoinduced cambial reactivation and tracheid formation, particularlyin the vicinity of needle or bud traces in the scion. In keepingwith this, it was found that the presence of needles and budswas essential for cambial reactivation in normal dormant stemsand that reactivation was restricted to the heated region. Key words: Grafting, Sitka spruce, callus, dormancy, differentiation     

The effect of acid irrigation on enzyme activities of the single partners of ectomycorrhizas from a limed stand of Norway spruce (Picea abies [L.] Karst.)

The aim of our investigations was to elucidate the effects of acid precipitation on some enzymes of the primary metabolism of ectomycorrhizas. Mycorrhizas of the type of Piceirhiza nigra Gronbach and of Russula ochroleuca (Pers.) Fr. and Tuber puberulum Berk. and Br. were collected from a stand of Norway spruce (Picea abies [L.] Karst.) during the growing seasons of 1991 and 1992. The experimental plots had been limed (Ca: 22 kmol ha_-1, Mg: 20 kmol ha_-1) in 1984 and exposed to acid irrigation (pH 2.7–2.8, H₂SO₄: 2 kmol ha_-1 a_-1) from 1984 to 1990. Crude extracts of mycorrhizas were assayed for the activities of glucose-6-phosphate dehydrogenase (G6P-DH, EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42) and NAD-dependent glutamate dehydrogenase (EC 1.4.1.2). The influence of the experimental treatments on these enzyme activities of the primary metabolism was generally low. For P. nigra, the activity of G6P-DH was decreased on the irrigated plot (photometric determinations). This seems to be a selective effect on the fungal partner, since quantitative enzyme electrophoresis revealed a decrease in the percentage of the fungal enzyme activity in relation to the total enzyme activity, whereas the content of the fungal compound ergosterol was not affected. A decrease in the fungal G6P-DH activity could also be detected in mycorrhizas of Tuber puberulum. There was also a seasonal variation in the proportion of fungal activity of G6P-DH in relation to the total G6P-DH activity. In the photometric assay (total activity) the effect was not discernible. This is indicative of a degree of regulation between the two partners, which could only be detected by quantitative enzyme electrophoresis. In addition, it could be deduced from the electrophoretograms, that in the case of G6P-DH and 6PG-DH the fungal enzyme activity was dominating in all mycorrhizas studied whereas in the case of ICA-DH the fungal band varied from being conspicuous to absent in different species of mycorrhizas. The banding pattern of G6P-DH was reproducibly different for all investigated species of mycorrhizas.