by Claire Morin | 30 January 2019
Published in Plant Cell, Tissue and Organ Culture 27: 95-103
Different carbohydrates were investigated for somatic embryo development of black spruce and red spruce. They were tested in a basal maturation medium consisting of Litvay’s salts at half-strength containing 1 g l-1 glutamine, 1 g l-1 casein hydrolysate, 7.5 mM abscisic acid, and 0.9% Difco Bacto-agar. A comparison of different sucrose concentrations showed that 6% was optimal for embryo development. Among the nine carbohydrates tested, sucrose, fructose, glucose, maltose, and cellobiose supported embryo development while arabinose, mannitol, myo-inositol, and sorbitol did not. A comparison of sucrose, glucose, and fructose at three concentrations showed that the general pattern of response for both species followed concentration expressed as a percentage, independent of the molarity of carbohydrate in the medium. Interspecific differences were observed concerning carbohydrate requirements. For red spruce, 6% fructose was found best for embryo development, while no such preference was observed for black spruce. No significant difference was observed in the number of embryos produced with 6% sucrose or 3% sucrose plus an equimolar concentration of either mannitol, sorbitol, or myo-inositol in the maturation medium, suggesting that the effect of the carbohydrate on the maturation was partly osmotic.
by Claire Morin | 30 January 2019
Published in American Journal of Botany 86(10): 1373-1381
Plants of black spruce (Picea mariana, N = 7047 individuals) and white spruce (P. glauca, N = 3995 individuals) were regenerated from a total of 87 clones over a 5-yr period by somatic embryogenesis to study factors that might be associated with the appearance of variant phenotypes. Morphological evaluation of the plants showed several types of variation. These variations were grouped into nine types: dwarfism (type A), reduced height with various form anomalies (types B, C, and D), needle fasciation (type E), abnormality in tree architecture (type F), variegata phenotype (type G), and plants with an overall regular morphology but smaller than normal plants (type H). Plagiotropic plants were also observed (type I). Each plant from types A to H (except type C where no plants survived more than 6 mo) had retained its phenotype over 4-5 yr of growth. Some of the variant types could be related to chromosomic instability: chromosome counts showed aneuploid cells for type-A and type-D plants. The type I (plagiotropism) was not related to genetic instability but rather to physiological disorders. In total, spruce variants of types A-H were obtained at relatively low frequencies, i.e., 1.0% (39/3995) for white spruce and 1.6% (110/7047) for black spruce. Statistical analyses, conducted with family, clone, and time in maintenance as variables, showed that clone was the most important source of genetic instability followed by time in maintenance.
by Claire Morin | 30 January 2019
Published in Plant Science 77: 233-242
Embryogenic tissue was obtained from immature zygotic embryos of black spruce (Picea mariana) and mature zygotic embryos of red spruce (Picea rubens). Embryogenic tissues were induced and maintained on half-strength Litvay’s medium supplemented with 10 mM 2.4-dichlorophenoxyacetic acid (2.4-D), 5 mM benzylaminopurine (BAP), 1 g/l casein hydrolysate, 500 mg/l glutamine, 1.0% (w/v) sucrose, and 0.9% (w/v) Difco Bacto-agar. To improve the maturation of somatic embryos, different gelling agents and ammonium nitrate concentrations were tested with a basal maturation medium consisting of HLM basal medium supplemented with 1 g/l glutamine, 1 g/l casein hydrolysate, 6% (w/v) sucrose, and 7.5 mM abcisic acid (ABA). The number of somatic embryos was significantly higher on medium solidified with Gelrite gellan gum than with Difco Bacto-agar. Corn, potato, wheat, or rice starches as gelling agents either did not influence or drastically reduced the development of black spruce somatic embryos. An ammonium nitrate concentration 3.4–10 mM for black spruce or 3.4–15 mM for red spruce was found to be optimal for embryo development. Maintenance of the embryogenic tissue under light or in darkness and use of different fluorescent lamps during the maturation stage did not influence the total number of black spruce somatic embryos produced. However, a maximum number of germinating embryos was produced when the embryogenic tissue was maintained in darkness, followed by a maturation stage in light.
by Marie-Claude Boileau | 30 January 2019
Published in Hydrological Processes 22: 4163-4172
In boreal forested wetlands, the observed increase in the water table level after clearcutting (watering-up) is often a threat to sustained ecosystem productivity. Hydrologic recovery refers to the processes by which a water table progressively drops back to its initial level after the cut. In eastern Canada, drainage is used operationally after clearcutting wet sites in order to lower the water table level and accelerate hydrologic recovery. The objective of this study was to evaluate the duration of the watering-up caused by timber harvesting and the extent to which drainage affected the water table recovery on five peatlands and three hydromorphic mineral sites located in the St. Lawrence Lowlands of Québec (Canada). The mixed wood stands studied are dominated by balsam fir (Abies balsamea (L.) Mill.), eastern white cedar (Thuja occidentalis L.), and red maple (Acer rubrum L.). Results indicate that, 10 years after clearcutting, water table levels in undrained plots are still 5 to 7 cm higher than the pre-cut levels. The slight recovery in water table level plateaued after the third year. Rainfall interception by vegetation was also monitored, and after 10 years had reached nearly 50% of the pre-cut rate. The immediate water table drawdown following drainage mitigated watering-up within 40 m of a ditch. The persistent watering-up observed in this study should encourage using sylvicultural systems adapted to boreal forested wetlands in order to prevent productivity loss and stand conversion.
by André Boily | 30 January 2019
Published in Simpson, J.D. (ed.). Proceedings of the Forum on the Conservation of Forest Genetic Resources: Challenges, Issues, and Solutions – Information Report M-X-220. July 28-29, 2006. Charlottetown, PEI. p. 48-54.
In 1996, the Québec government adopted a strategy and an action plan to meet its commitments with regard to the objectives of the Convention on Biological Diversity. Action took place in 2000 with the creation of protected areas, aimed at conserving species and ecosystems. Six years later, 4.79% of the land base has been designated as protected area, mainly located in northern Québec. In the future, new protected areas will be needed in southern Québec, where there is high human pressure on existing forest ecosystems and where species at risk are located. From a forest genetic resource point of view, it is not yet clear how many protected areas should be created to ensure that most of the genetic diversity of each species is maintained. Recently, Québec adopted a forest management strategy aimed at maintaining the biodiversity and viability of all of the forest ecosystems. Ecosystem-based management, as it is called, will help to maintain the genetic integrity of natural populations within a broader diversity of forest structural classes at the landscape level.
For now, Québec is relying on these conservation measures, which act as a coarse filter, to conserve the genetic diversity, but it has no strategy targeting the specific requirements of each species. Most current knowledge has been obtained through genetics and tree improvement programs and relates mainly to boreal forest conifer species. Genetic marker studies, which began toward the end of 1980s, show that most of these species have a high level of genetic diversity that is little impacted by forest practices. However, there is little or no basic knowledge about the genetic diversity of most of the deciduous hardwood species located in southern Québec. Promoting the work taking place in British Columbia and Alberta, and the creation of CONFORGEN, could be of great help in informing decision makers, and could lead to concrete action in Québec.
