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The balance between allocating energy resources to reproduction or growth has considerable theoretical interest. Conflicting ecological requirements and evolutionary pressures often necessitate a trade-off in energy allocation. We obtained measurements on seed-cone production and annual ring width of 365 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees from 29 open-pollinated families for 8 years. Phenotypic, genetic, and environmental correlations were computed for seed-cone production and ring width for each year. Five of the eight environmental correlations were negative (range −0.077 to −0.305), reflecting the reality of the trade-off in physiological terms. Six of the eight genetic correlations were negative (range −0.199 to −0.776), indicating that a trade-off exists at the genetic level between energy allocation to reproduction and to somatic growth. These findings agree with the current theory of life-history evolution. Key words: Pseudotsuga menziesii, cone production, annual ring width, genetic correlation.

We used DNA fingerprinting and pedigree reconstruction to determine the genetic relationship among members of 3 yellow-cedar (Callitropsis nootkatensis [D. Don] Oerst.) selection populations in the absence of their parental genotypes. Selection population members consisted of the tallest individuals within seedling crops originated from natural stand seed collected from multiple seed donors covering wide areas within 3 distinct locations (phenotypic mass selection). Pairwise relative kinship estimates indicated the presence of extensive coancestry among the selected seedlings, and pedigree reconstruction grouped each selection members into multiple full-sib families of different sizes (1-10) nested within several half-sib families (19-21). The "STRUCTURE" program (Pritchard JK, Stephens M, Donnelly P. 2000. "Inference of population structure using multilocus genotype data." Genetics. 155:945-959.) provided a pictorial classification of the 3 selection populations and grouped their individuals into multiple cohorts (9-10). The STRUCTURE program's results corresponded with that of the pedigree reconstruction, indicating that members of the selection populations originated from a subset of the seed donors forming the natural stand seed collections. The species' silvics, reproductive biology, methods of natural stand seed collection and seedling production, and the high selection intensity applied to form the selection populations contributed to limiting the selection to a subset of the original donor trees. The associated buildup of coancestry in selection and production populations is expected to result in inaccurate estimation of genetic parameters and an unintentional reduction in genetic diversity in reforestation stocks.

SummaryAn innovative approach to tree breeding called ‘breeding without breeding’ (BWB) is presented. The method, as applied on the material in hand, allows the capture of 75–85% of the genetic response to selection attained through conventional programmes without the need to do any controlled pollination and simplified or possibly no experimental field testing: both considered to be the most resource-demanding activities in breeding programmes. BWB combines the use of genotypic or phenotypic pre-selection of superior individuals, informative DNA markers for fingerprinting and pedigree reconstruction of offspring to assemble naturally created full- and half-sib families resulting from mating among selected parents, and quantitative genetics analyses to identify elite genotypes for further genetic improvement or the establishment of production populations. BWB utility is demonstrated using a retrospective study of Douglas-fir (Pseudotsuga menziesii) progeny tests consisting of offspring produced from 150 controlled crosses among 60 parents and established over three sites. The empirical results are supported by theoretical expectations demonstrating anticipated minimum genetic response compared with conventional approaches. The method's simplicity offers an exceptional opportunity for the development of comparable breeding efforts in developing countries, advanced and new breeding programmes, and economically important and ‘minor’ species.

In 1987, a study was initiated to determine the properties of seed from apparently premature cones of yellow-cedar (Chamaecyparisnootkatensis (D. Don) Spach) on southwestern Vancouver Island. After pollination with fresh pollen in February, all cones showed signs of maturation (i.e., drying and shedding) by December. Samples of these 1-year-old cones were collected for seed extraction and germination tests. Germination ranged between 10 and 42% for isolated cones (i.e., bagged) and between 0 and 25% for unisolated cones. Similar germination results were obtained for the 1988 and 1989 cone crops. Anatomical observations revealed that the 10-month-old embryos were similar in both size and shape to embryos from 2-year-old seeds. It was concluded that transplanting yellow-cedar trees to warmer, low-elevation sites enabled seed cones to continue development without significant delay caused by dormancy induced by cold temperatures at higher elevations. This alteration of normal phenology reflects the impact of environmental contingencies on development.

The cloning of white spruce (Picea glauca) mitochondrial DNA homologous to the cytochrome oxidase II and ATPaseα genes of maize is described. These probes were used to define restriction fragment length polymorphisms which distinguish the white, Engelmann (P. engelmannii) and Sitka spruce (P. sitchensis) populations that occur in British Columbia. Analysis of progeny from crosses between the species revealed that mitochondrial DNA was maternally inherited in all cases (32 progeny from five independent crosses). The inheritance of chloroplast DNA was determined using a probe described previously; in this case, all progeny exhibited paternal inheritance (27 progeny from four crosses). Mitochondrial and chloroplast probes were used to test trees from zones of introgression between coastal (Sitka) and interior spruces (white and Engelmann). In most cases mitochondria and chloroplasts within individuals were contributed by different species. The data shows that there is a significant Sitka spruce component in trees east of the coastal watershed in British Columbia.

The mating system of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] was examined in two genetically similar seed orchard blocks with the aid of allozyme polymorphisms at six loci. The pollination environment (time of pollination and length of pollination season) of one block was manipulated by means of an overhead water spray cooling treatment. The cooling treatment temporarily delayed the pollination season in the treated block by 12 days relative to the untreated one. In addition, the length of the pollination season in the cooled block was shorter than the uncooled one by 12 days (18 vs. 30 days). The rate of inbreeding was significant in the uncooled block, while a perfect outcrossing rate was obtained for the cooled one. This difference was attributed to the low outcrossing rate obtained within the lower crown of the control block. It was concluded that the observed significant selfing in the uncooled block was caused by the first-pollination primacy that permitted related pollen to out-compete unrelated pollen in the extended pollination season. A shorter pollination season produced a dense pollen cloud of related and unrelated pollen, hence, early zygotic selection favoured unrelated embryos. An extended pollination season, on the other hand, permitted related pollen to succeed in pollination and fertilization without any challenge by unrelated pollen. Controllable variation in the rate of inbreeding reported in this study could be useful to improve the genetic quality of seed produced from seed orchards and consequently to maximize genetic gains from selections.

Douglas-fir seedlots were treated with the Incubation Drying Separation (IDS) method to test whether seeds infested with the seed chalcid, Megastigmus spermotrophus Wachtl, could be separated from non-infested seeds. Seeds were soaked in distilled water for 24 h, drained, placed in plastic bags and incubated at 15 °C for 3 days. The seeds were dried for either 0.5, 1, or 2 h at 25 °C, and then separated into floaters and sinkers in a water column. An average of 97% of the infested seed floated. The drying period did not affect the separation of infested seeds but significantly fewer sound seeds floated in the seedlots dried for 0.5 h than those dried for 1 h. Germination capacity of IDS-treated seeds did not differ from that of untreated seeds but the germination rate was significantly faster for IDS-treated seeds when all lots were stratified.

Reproductive bud phenology and seed-cone crop of a Sitka-spruce [Picea sitchensis (Bong.) Carr.] seed-orchard were studied to assess the validity of two seed-orchard assumptions, namely panmictic equilibrium, and parental balance. Also, the impact of supplemental mass pollination as a crop-management practice was evaluated. The study revealed significant variation in reproductive bud-development timing as well as proportion of reproductive strobili. A lack of mature male cones was observed while the majority of seed cones were in their receptive stage. It was also observed that approximately 80% of the seed-cone crop was produced by only 20% of the orchard clones. Supplemental mass pollination produced a 14-fold difference in the number of filled seeds per cone compared to that produced under wind pollination. In addition to the significant increase in seed-yield, supplemental mass pollination is proposed as a management option in Sitka-spruce seed-orchards to alleviate the effect of parental imbalance and panmictic disequilibrium.

Overhead-cooling treatment used to delay flowering produced non-significant effects on germination capacity, germination rate, germination value, and abnormal germination of seeds from a 13-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedling seed orchard. The percentage of variation accounted for by cooling treatment ranged from 0.0 to 1.0%. In contrast, variation among trees within treatments ranged from 28 to 46%. These effects were significant, indicating that each tree has an individual germination pattern. The temporal delay of reproductive phenology caused by temperature manipulation as a result of the cooling treatment was judged to be within the species' biological limits.

White pine blister rust is caused by the fungal pathogen Cronartium ribicola J.C. Fisch (Basidiomycota, Pucciniales). This invasive alien pathogen was introduced into North America at the beginning of the 20th century on pine seedlings imported from Europe and has caused serious economic and ecological impacts. In this study, we applied a population and landscape genetics approach to understand the patterns of introduction and colonization as well as population structure and migration of C. ribicola. We characterized 1,292 samples of C. ribicola from 66 geographic locations in North America using single nucleotide polymorphisms (SNPs) and evaluated the effect of landscape features, host distribution, and colonization history on the structure of these pathogen populations. We identified eastern and western genetic populations in North America that are strongly differentiated. Genetic diversity is two to five times higher in eastern populations than in western ones, which can be explained by the repeated accidental introductions of the pathogen into northeastern North America compared with a single documented introduction into western North America. These distinct genetic populations are maintained by a barrier to gene flow that corresponds to a region where host connectivity is interrupted. Furthermore, additional cryptic spatial differentiation was identified in western populations. This differentiation corresponds to landscape features, such as mountain ranges, and also to host connectivity. We also detected genetic differentiation between the pathogen populations in natural stands and plantations, an indication that anthropogenic movement of this pathogen still takes place. These results highlight the importance of monitoring this invasive alien tree pathogen to prevent admixture of eastern and western populations where different pathogen races occur.

Microsatellites, or simple sequence repeats (SSRs), are usually regarded as the “markers of choice” in population genetics research because they exhibit high variability. The development cost of these markers is usually high. In addition, microsatellite primers developed for one species often do not cross-amplify in related species, requiring separate development for each species. However, microsatellites found in expressed sequence tags (ESTs) might better cross-amplify as they reside in or near conserved coding DNA. In this study, we identified 14 Pinus taeda (loblolly pine) EST-SSRs from public EST databases and tested for their cross-species transferability to P. contorta ssp. latifolia, P. ponderosa, and P. sylvestris. As part of our development of a P. contorta microsatellite set, we also compared their transferability to that of 99 traditional microsatellite markers developed in P. taeda and tested on P. contorta ssp. latifolia. Compared to traditional microsatellites, EST-SSRs had higher transfer rates across pine species; however, the level of polymorphism of microsatellites derived from ESTs was lower. Sequence analyses revealed that the frequencies of insertions/deletions and base substitutions were lower in EST-SSRs than in other types of microsatellites, confirming that EST-SSRs are more conserved than traditional SSRs. Our results also provide a battery of 23 polymorphic, robust microsatellite primer pairs for lodgepole pine.

Genetic diversity and mating system were quantified for shelterwood, patch cut and green tree-retention silvicultural systems, and compared to adjacent old-growth. This is a component of a larger study conducted in montane old-growth forests of coastal British Columbia to evaluate the feasibility and ecological consequences of alternative silvicultural systems. The experiment includes replicated treatments representing a range of overstory removal adjacent to old-growth and clearcut areas. Based on 22 electrophoretically assayed loci, the effects of silvicultural systems on genetic parameters of amabilis fir (Abies amabilis and western hemlock (Tsuga heterophylla were assessed by comparing an average number of alleles per locus, the percent polymorphic loci, and observed and expected heterozygosity between parental populations and naturally regenerated progeny as well as among treatments. Genetic variation in natural regeneration was greater than in parental populations, especially for low-frequency alleles. Silvicultural treatments caused no significant differences in amabilis fir genetic-diversity parameters, while the shelterwood system resulted in lower observed and expected heterozygosity in western hemlock. Nei's genetic distance revealed that all parental populations were extremely similar. The two species had contrasting mating system dynamics with amabilis fir producing higher levels of correlated paternity and inbreeding with wider variation among individual tree outcrossing-rate estimates. Western hemlock had significant levels of correlated paternity only for the green tree and shelterwood treatments demonstrating family structuring inversely related to stand density. Inbreeding in western hemlock was significant but lower than that observed for amabilis fir with a J-shaped distribution for individual tree multilocus outcrossing-rate estimates. The pollination and dispersal mechanisms of the two species represent the most-likely factors causing these differences. Artificial regeneration may be utilized to augment the genetic resources of natural ingress.

Over 18 million ha of forests have been destroyed in the past decade in Canada by the mountain pine beetle (MPB) and its fungal symbionts. Understanding their population dynamics is critical to improving modeling of beetle epidemics and providing potential clues to predict population expansion. Leptographium longiclavatum and Grosmannia clavigera are fungal symbionts of MPB that aid the beetle to colonize and kill their pine hosts. We investigated the genetic structure and demographic expansion of L. longiclavatum in populations established within the historic distribution range and in the newly colonized regions. We identified three genetic clusters/populations that coincide with independent geographic locations. The genetic profiles of the recently established populations in northern British Columbia (BC) and Alberta suggest that they originated from central and southern BC. Approximate Bayesian Computation supports the scenario that this recent expansion represents an admixture of individuals originating from BC and the Rocky Mountains. Highly significant correlations were found among genetic distance matrices of L. longiclavatum, G. clavigera, and MPB. This highlights the concordance of demographic processes in these interacting organisms sharing a highly specialized niche and supports the hypothesis of long-term multipartite beetle-fungus co-evolutionary history and mutualistic relationships.

The correlation between 99 clone female and male fertilities in a first generation seed orchard of Pinus densiflora was studied over 6 years. The effective number of the parent ( N(p)) and the variance effective population number [ N(e)((v))] were used to assess the impact of total (Psi(T)), female (psi(f)) and male (psi(m)) fertility variation. A theoretical framework was developed to account for female and male fertility correlations as well as the impact of possible pollen contamination. Total fertility variation was described by the sibling coefficient (Psi(T): the probability that two genes randomly chosen from the gamete gene pool originate from the same parent), which was further subdivided into psi(f) and psi(m). These parameters were compared under various conditions including the total seed harvest, imposing on equal seed harvest among the orchard's clones and two contamination scenarios ( M = 0 and 20%). Fertility variations among females, males and clones were observed within and among years. Sibling coefficients (Psi(T)) were lower, but the effective number of parent ( N(p)) and variance effective population number ( N(e)((v))) were higher in years with moderate female and good male strobilus production. N(p) for female and male reproductive outputs varied from 49 to 82 and from 57 to 93, respectively. N(p) was higher for males than females. When the crop of the 6 years was pooled, N(p) for female, male and the clone were 73, 87 and 85, respectively. The impact of female-male fertility correlation for conditions with no-, positive- and negative-correlations were assessed and their impact on Psi(T), N(p) and N(e)((v)) was also evaluated. It was demonstrated that the practice of equal seed harvesting from every clone, or the mixing of seeds from several years, would substantially improve the genetic diversity and the genetic representation of the seed orchard population when a positive correlation between gender fertilities was observed. The relevance of these results to supplemental-mass-pollination was discussed under two cases where equal- and un-equal amounts of pollen from clones were included in the pollen mixes.

Somatic embryogenesis (SE) offers advantages in tree breeding due to the genetic gain improvements that can be realized through selection and production of elite (clonal) lines. Additionally, it is a platform through which value-added traits can be introduced via genetic engineering. At CellFor considerable effort has been directed towards the improvement of SE protocols for coniferous species, with significant focus placed on development in vitro. Recent progress includes rapid bulk-up of cultures via liquid culture, production of desiccation-tolerant embryos in bioreactors and direct delivery of somatic seed to the nursery. Additionally, transgenic spruce, loblolly pine and radiata pine have been developed via SE, with the targets including enhanced cellulose synthesis, lignin modification and control of key developmental pathways As a tool for tree improvement, conifer SE circumvents the infrastructure and time constraints that are inherent to production of improved seed via seed orchards. The application of SE in this context necessitates the development of a deployment strategy that addresses genetic diversity and the genetic gain achieved. Approaches, based on the principles of population genetics, have been developed to optimize both the initial selection strategy and subsequent deployment of clonal lines. Since 1995, CellFor and its predecessor companies have implemented commercial programs for spruce (interior; Sitka), pine (loblolly; radiata; slash) and Douglas-fir. Annual volume production in excess of 1 million seedlings has been achieved.

Domestication of forest tree species can be characterized as taking genotypes from their wild, undomesticated state through a series of sampling and selection stages, each with the potential of reducing genetic variation and in the same time resulting in genetically superior plantations (El-Kassaby and Namkoong 1994,1995). This domestication follows a systematic process by which the populations involved descend from large collections to screening and testing, and finally to advanced breeding with small sets of parents before incorporation in production populations (i.e., seed orchards).

Statistical analyses of trees produced from wind-pollinated seeds to determine levels of additive variance need to be adjusted to compensate for the relationships among the progeny. The assumption that the coefficient of relationship among the progeny is 0.25 will lead to inaccurate estimation of the additive variance if the relationships among the progeny are not entirely half-sib. Foreign pollen intrusion into the orchard pollen cloud, selfing, and reproductive phenology variation (i.e., mating proportion differences) among the parent trees may lead to varying proportions of self, self-half, half-sib, and full-sib relationships among the progeny. The variance of the coefficient of relationship from 0.25 for two coniferous seed orchards subjected to simulated selfing and foreign pollen problems illustrate the need for caaution when estimation techniques are employed.

Cet article etudie les relations entre energie reproductive (nombre de cones produits par un arbre) et succes reproductif (nombre de graines produites). L'impact de ces 2 facteurs sur la contribution de chaque clone a la production de graines d'un verger d'epicea de Sitka durant 2 annees successives est egalement aborde. Les estimations du nombre efficace d'arbres meres rendent bien compte de la contribution tres inegale des differents clones a la production de graines. Cependant, elles ne mettent pas en evidence les differences clonales entre energie reproductive et succes reproductif (.)

Microsatellites are codominant and highly polymorphic genetic markers. They are widely used in studying parentage and reproductive success in many insect species. We developed six microsatellite markers in Pissodes storbi . The number of alleles per locus ranges from 5 to 16 alleles, with a mean number of 10. The high allelic diversity observed in this study showed that they could be useful in the study of parentage and reproductive success in P. strobi .

International audience; Pollination dynamics was studied in a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed orchard using 8 nuclear microsatellite markers and pedigree reconstruction.* The seed orchard consisted of 49 parents (clones). Cone-crop management included bloom delay and supplemental mass pollination (SMP) using 12 internal and 4 external pollen donors.* A random sample of 801 bulk seeds was genotyped for both haploid megagametophyte and corresponding diploid embryo.* Using the parental population's multilocus genotypes, full pedigree reconstruction generated all the information needed to estimate the maternal, paternal, and parental reproductive success, selfing, pollen contamination, and pollination success of the 4 external pollen donors.* Maternal, paternal, and parental reproductive success varied with 80% of gametes being produced by 23, 45, and 37% of the orchard's parents, respectively, resulting in a drastically reduced effective population size as compared to the census number (14 vs. 53).* Selfing, pollen contamination, and aggregate SMP success (internal and external) were estimated to be 15.2, 10.4, and 15.0%, respectively.* Full pedigree reconstruction was effective in unraveling the orchard's pollination dynamics and both female and male reproductive success.

Trace-element profiles for seeds collected from 10 International Union of Forest Research Organization provenances of Sitka spruce (Piceasitchensis [Bong.] Carr.) from the Pacific Northwest were determined by X-ray energy-dispersive spectrometry. Stepwise discriminant analyses were used to examine potential significant differences among groups and separate samples were used as unknowns to test each discriminant function. Three analyses were made, the first to discriminate among the 10 provenances, the second to discriminate among the five Canadian provenances only, and the third to discriminate the Canadian provenances grouped by soil types at provenance origin. Significant differences (P

Spatial variability in heights of 8-year-old Douglas-fir in a IUFRO provenance–progeny transfer test was analyzed using trend surface analysis to differentiate genetic and environmental effects on tree height. The test installation was located in the University of British Columbia Research Forest, and was a randomized incomplete block design with three replications. Only the 25 provenances that were replicated in each block and had a balanced data set (eight families, five trees per family) were used. Trends were fitted to the average height of each replicate of each provenance, and also to the average size of the largest and smallest families per replicate. Interpretation was based on the assumption that the effects of microsite (mainly grass invasion of one block) were defined by the trend surface, while genetic effects were represented by the residuals from the trend. The data had previously been analyzed by ANOVA methods and these results were contrasted with the results using trend surface analysis. Trend surface analysis generally gave results similar to ANOVA, but in some cases resulted in different conclusions. Additional insights into the interaction of genotype and environment were obtained. Trend surface analysis is proposed as a useful supplement to analysis of variance in provenance transfer studies. Potential problems in using the method are discussed.

The joint levels of outcrossing and contamination in two young northern Swedish Scots pine (Pinus sylvestris L.) seed orchards were studied with the aid of allozyme markers. High levels of contamination (21–36%) were estimated and were attributed to the observed low within orchard pollen production. Outcrossing rate estimates were high (0.957–0.961), though they departed significantly from complete outcrossing (t= 1.0) in spite of the observed high contamination levels. These results confirmed reported relationships between outcrossing and contamination levels in open‐pollinated seed orchards. It was concluded that a crop management option relying on supplemental mass‐pollination would be effective in reducing both contamination and inbreeding levels.

Genetic variation at 24 enzyme loci was studied for 10 IUFRO populations of Sitka spruce (Piceasitchensis (Bong.) Carr.). The average proportion of polymorphic loci per population was 0.51 ± 0.02 and the average proportion of heterozygous loci per individual was 0.15 ± 0.03. The following generalizations were advanced: (1) the amount of genetic polymorphism varied considerably from locus to locus; (2) many populations were similar in the amount and pattern of genetic variation for most loci; (3) but some loci had large differences among populations.Eight percent of the gene diversity was attributed to interpopulation differentiation; 92% of the total gene diversity resided within populations. Pairwise comparisons of genetic distances averaged 0.014, a value which reflected very little differentiation between geographic sources.

Variation in growth rate in the four uppermost lateral branches of seedlings of Pseudotsuga menziesii (Mirb.) Franco was greatest among individuals within full-sib families. These results are consistent with those from other studies on conifers indicating there is much more within- than among-intraspecific group variation. Since these seedlings were grown in a common garden, it is assumed that the among-individual variation has a genetic basis. The greatest growth rate was in seedlings produced by crossing trees that had the highest average increments of growth; the lowest growth rate was in seedlings produced by crossing trees that had the lowest average increments of growth. However, the seedlings with the lowest growth rate were similar to those produced by crosses between trees with high average increments of growth. This implies that phenotypically superior trees, as assessed in a natural situation, do not necessarily produce superior offspring in their second year of growth. The high within-family variation coupled with the ontogenetic events associated with growth rate implies a complex multigenic control of growth rate. The genetic complexity of an apparently simple developmental event such as growth in length implies that evolutionary or developmental models based on a small portion of the genome may be inadequate.

The genetic variation at 27 allozyme loci and seven different seedling traits were studied in a coastal stand of Douglas-fir [Pseudotsuga menziesii var. menziesii (Mirb.) Franco] with respect to different elevation classes. The average proportion of polymorphic loci per elevation class was 0.54 ± 0.06 and the average proportion of heterozygous loci per individual was 0.17 ± 0.02. The isozyme data showed that the amount of genetic polymorphism varied considerably between loci and the amount and pattern of genetic variation for most loci were similar among the different elevational classes although some loci had large differences among elevational classes. Seven % of the total genic diversity was attributed to interelevational differentiation while the remaining 93% resided within the different elevational classes. Good agreement occurred between the isozyme data and quantitative information obtained from half-sib families of the same trees used for the isozyme analysis. The analyses of variance for the studied traits gave the same general trend and variation within the different elevational classes varied between 94 to 100%. In general, both the quantitative and the isozyme studies showed that the majority of variation resided within and not among the different elevation classes. Using these two different approaches in assessing variation in natural population is recommended.

Effect of sample size on accuracy and precision of provenance mean height, genetic variance components and heritability were studied in a 10-year-old IUFRO Douglas-fir [ Pseudotsuga menziesii ( (Mirb.) Franco] provenance-progeny trial. Estimates of these parameters, and their respective standard errors, were computed for different numbers of families within provenances, and trees within families. Accuracy of mean height estimates did not differ appreciably with changes in either family number or size. However, precision of the mean height estimates was affected by changes in the family size. Both accuracy and precision of additive genetic variance and heritability estimates were greatly influenced by the number and size of families. Based on estimates obtained empirically, optimum sample sizes for the number of families per provenance and the number of trees per family was proposed and compared with those obtained from analysing the data as a provenance trial (i. e., no family structure). The optimization of sample size will improve the efficiency of provenance-progeny testing.

Numerical data were collected from the karyotypes of seven species in the Pseudotsuga genus. These included two North American species, P. macrocarpa and P. menziesii, the latter with two varieties (P. menzeisii var. menziesii and P. menziesii var. glauca) and five Asiatic species, P. japonica from Japan, P. wilsoniana from Taiwan, and P. forrestii, P. sinensis, and P. gaussenii from China. A stepwise discriminant function analysis was employed to test the validity of using karyotype data for characterizing the cytogenetical and the geographical differences of each species. Good discrimination was shown among P. macrocarpa and the Asiatic species. The discrimination among the Asiatic species was further improved when the well-separated P. macrocarpa was omitted. A high level of discrimination was observed between the two P. menziesii varieties. This statistical technique was particularly helpful in selecting variables that best separated the taxa. To our knowledge, these results provide the first reported karyotype numerical analysis for the Pseudotsuga genus as well as the first reported karyotype analysis for P. gaussenii.

The morphological variation of seedlings from a single population of Pseudotsuga menziesii was examined and related to their maternal parentage (41 families) and speed of germination (selection) during the course of a common garden experiment. The largest source of variation among seedlings was attributed to within-family variation. Furthermore, within-family variable intercorrelations differed from family to family, suggesting that intrinsic causal factors are important to the generation and organization of variation. Pooled within-family variation was explored and shown to be related to the between-family variation. These results suggest that developmental and historical factors cannot be ignored in the interpretation and exploitation of sources of variation. Such considerations identify limitations to Neo-Darwinian explanations and suggest reappraisal of progeny trials with respect to these issues. The results also pose limitations to our interpretations of genetic similarity on the basis of multivariate morphological data.

Edwards, D.G.W. and EI-Kassaby, Y.A., 1988. Effect of flowering phenology, date of cone collection, cone-storage treatment and seed pretreatment on yield and germination of seeds from a Douglas-fir seed orchard. For. Ecol. Manage., 25: 17-29. The effects of reproductive phenology, date of cone harvest, cone storage and seed pretreatment on yield and germination of seeds from a Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seed orchard were studied. Flowering phenology (early, intermediate or late) had no discernible effect on seed maturation. Higher germination and yields of filled seeds were obtained from cones collected in mid-August, approximately 2 weeks prior to cone opening, than from cones collected just as they began to open. Seeds extracted immediately following harvest germinated better than those from cones stored for 2 months. Seeds from all treatments were dormant and responded to prechilling by exhibiting increased germination rates. The implications of these findings for conecrop management are discussed.

A multivariate extension of univariate sample size estimation is outlined that enables one to determine sample size for a multivariate study. The procedure is presented and illustrated by application to intraindividual and interindividual variation of cone morphology in a population of Picea sitchensis (Bong.) Carr. The method involves the stabilization of a scalar estimate of the structure of the correlation matrix (the determinant) among variables for a given sample size. The sample-specific dependency of previously described methods is avoided by random selection of several replicates in nonstructured and structured (nested) models. The procedure is best applied in pilot studies where it can aid in the characterization of multivariate data prior to analysis. Additionally, repeatability estimates for cone scale morphology are presented.

The amounts of self-fertilization versus consanguineous matings (as measured by effective selfing) was estimated in a seed orchard of Douglas-fir, using progeny array data at six allozyme loci. The orchard is family structured, consisting several grafts (clones) and/or open-pollinated (o-p) progeny from each of several 'plus-trees'. Population-wide selfing rates were found to be 7% for the o-p trees and 2% for the cloned trees. Estimates of mating system parameters for individual trees showed this difference for average outcrossing rate t (1) still largely remained when outcrossingpollen gene frequency p was not allowed to vary among trees and (2) disappeared when p was allowed to vary among trees. Under this joint t and p estimation, o-p trees showed both significant variation of t (based upon a one-way ANOVA grouped by common plus-tree) and significant regressions of p on ovule genotype (indicative of consanguineous matings); cloned trees showed neither. This higher rate of consanguineous mating for o-p trees might be explained by the larger and more variable size of o-p families in the orchard. Estimates of outcrossing rate t and outcrossingpollen gene frequency p were based upon a multilocus model which makes full use of the information in the data. The increased information it gives over 'observed outcross' models is equivalent to adding 30-50% more loci, and it gives enough degrees of freedom to jointly estimate t and p for individual trees (individual progeny arrays) under certain conditions. In addition, inclusion of megagametophyte data nearly doubles the information about the mating system of individual trees.

Seeds from four ramets in each of six clones of 17-year-old Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco, grown in a Saanichton, B.C., seed orchard on common rootstock were examined by X-ray energy-dispersive spectrometry to determine variations in trace element profiles. These profiles were analysed by discriminant function analysis and shown to be specific for each clone with 80.4% of seeds being correctly classified to original clone. Since the ramets were all grown in a similar orchard environment, these results support the hypothesis that elemental uptake by seeds of Douglas-fir is under genetic control.

Seeds from 21 populations of Piceamariana (Mill.) B.S.P. from five forest sections of the boreal forest regions in Newfoundland were analyzed for electrophoretically detectable variation in 15 proteins coded by 23 genetic loci. On the average, 38% of the loci per population were polymorphic, the number of alleles per locus was 1.44, and the expected and observed heterozygosities were 0.107 and 0.120, respectively. Contingency χ2 analysis for homogeneity of allele frequencies indicated differentiation (P

Effects of maternal genotypes for eight enzyme loci on seven quantitative traits in 41 half-sib families were determined. Heritability estimates for the quantitative traits were highly significant and ranged from 0.57 to 0.86. Only six of 112 comparisons (56 comparisons for each of the genotypes and 56 for homozygous versus heterozygous contrasts) were statistically significant (P < 0.05). None of these significant comparisons could be associated with either a particular allele or a particular genotype. No heterotic effects were observed when the homozygous genotypes were compared with the heterozygous ones. Because the quantitative traits are highly correlated, a discriminant function analysis was performed to obtain the two most important canonical variates that accounted for 75% of the variance in the quantitative traits. There were no significant associations among enzyme loci and the two canonical variates. I conclude that, in this study, enzyme genotypic differences do not influence the quantitative traits to a major extent.

Background Seeds use environmental cues such as temperature to coordinate the timing of their germination, allowing plants to synchronize their life history with the seasons. Winter chilling is of central importance to alleviate seed dormancy, but very little is known of how chilling responses are regulated in conifer seeds. White spruce (Picea glauca) is an important conifer species of boreal forests in the North American taiga. The recent sequencing and assembly of the white spruce genome allows for comparative gene expression studies toward elucidating the molecular mechanisms governing dormancy alleviation by moist chilling. Here we focused on hormone metabolite profiling and analyses of genes encoding components of hormone signal transduction pathways, to elucidate changes during dormancy alleviation and to help address how germination cues such as temperature and light trigger radicle emergence. Results ABA, GA, and auxin underwent considerable changes as seeds underwent moist chilling and during subsequent germination; likewise, transcripts encoding hormone-signaling components (e.g. ABI3, ARF4 and Aux/IAA) were differentially regulated during these critical stages. During moist chilling, active IAA was maintained at constant levels, but IAA conjugates (IAA-Asp and IAA-Glu) were substantially accumulated. ABA concentrations decreased during germination of previously moist-chilled seeds, while the precursor of bioactive GA1 (GA53) accumulated. We contend that seed dormancy and germination may be partly mediated through the changing hormone concentrations and a modulation of interactions between central auxin-signaling pathway components (TIR1/AFB, Aux/IAA and ARF4). In response to germination cues, namely exposure to light and to increased temperature: the transfer of seeds from moist-chilling to 30 °C, significant changes in gene transcripts and protein expression occurred during the first six hours, substantiating a very swift reaction to germination-promoting conditions after seeds had received sufficient exposure to the chilling stimulus. Conclusions The dormancy to germination transition in white spruce seeds was correlated with changes in auxin conjugation, auxin signaling components, and potential interactions between auxin-ABA signaling cascades (e.g. the transcription factor ARF4 and ABI3). Auxin flux adds a new dimension to the ABA:GA balance mechanism that underlies both dormancy alleviation by chilling, and subsequent radicle emergence to complete germination by warm temperature and light stimuli. Electronic supplementary material The online version of this article (doi:10.1186/s12870-015-0638-7) contains supplementary material, which is available to authorized users.

Background Genomic selection (GS) in forestry can substantially reduce the length of breeding cycle and increase gain per unit time through early selection and greater selection intensity, particularly for traits of low heritability and late expression. Affordable next-generation sequencing technologies made it possible to genotype large numbers of trees at a reasonable cost. Results Genotyping-by-sequencing was used to genotype 1,126 Interior spruce trees representing 25 open-pollinated families planted over three sites in British Columbia, Canada. Four imputation algorithms were compared (mean value (MI), singular value decomposition (SVD), expectation maximization (EM), and a newly derived, family-based k-nearest neighbor (kNN-Fam)). Trees were phenotyped for several yield and wood attributes. Single- and multi-site GS prediction models were developed using the Ridge Regression Best Linear Unbiased Predictor (RR-BLUP) and the Generalized Ridge Regression (GRR) to test different assumption about trait architecture. Finally, using PCA, multi-trait GS prediction models were developed. The EM and kNN-Fam imputation methods were superior for 30 and 60% missing data, respectively. The RR-BLUP GS prediction model produced better accuracies than the GRR indicating that the genetic architecture for these traits is complex. GS prediction accuracies for multi-site were high and better than those of single-sites while multi-site predictability produced the lowest accuracies reflecting type-b genetic correlations and deemed unreliable. The incorporation of genomic information in quantitative genetics analyses produced more realistic heritability estimates as half-sib pedigree tended to inflate the additive genetic variance and subsequently both heritability and gain estimates. Principle component scores as representatives of multi-trait GS prediction models produced surprising results where negatively correlated traits could be concurrently selected for using PCA2 and PCA3. Conclusions The application of GS to open-pollinated family testing, the simplest form of tree improvement evaluation methods, was proven to be effective. Prediction accuracies obtained for all traits greatly support the integration of GS in tree breeding. While the within-site GS prediction accuracies were high, the results clearly indicate that single-site GS models ability to predict other sites are unreliable supporting the utilization of multi-site approach. Principle component scores provided an opportunity for the concurrent selection of traits with different phenotypic optima. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1597-y) contains supplementary material, which is available to authorized users.

Background QTL cloning for the discovery of genes underlying polygenic traits has historically been cumbersome in long-lived perennial plants like Populus. Linkage disequilibrium-based association mapping has been proposed as a cloning tool, and recent advances in high-throughput genotyping and whole-genome resequencing enable marker saturation to levels sufficient for association mapping with no a priori candidate gene selection. Here, multiyear and multienvironment evaluation of cell wall phenotypes was conducted in an interspecific P. trichocarpa x P. deltoides pseudo-backcross mapping pedigree and two partially overlapping populations of unrelated P. trichocarpa genotypes using pyrolysis molecular beam mass spectrometry, saccharification, and/ or traditional wet chemistry. QTL mapping was conducted using a high-density genetic map with 3,568 SNP markers. As a fine-mapping approach, chromosome-wide association mapping targeting a QTL hot-spot on linkage group XIV was performed in the two P. trichocarpa populations. Both populations were genotyped using the 34 K Populus Infinium SNP array and whole-genome resequencing of one of the populations facilitated marker-saturation of candidate intervals for gene identification. Results Five QTLs ranging in size from 0.6 to 1.8 Mb were mapped on linkage group XIV for lignin content, syringyl to guaiacyl (S/G) ratio, 5- and 6-carbon sugars using the mapping pedigree. Six candidate loci exhibiting significant associations with phenotypes were identified within QTL intervals. These associations were reproducible across multiple environments, two independent genotyping platforms, and different plant growth stages. cDNA sequencing for allelic variants of three of the six loci identified polymorphisms leading to variable length poly glutamine (PolyQ) stretch in a transcription factor annotated as an ANGUSTIFOLIA C-terminus Binding Protein (CtBP) and premature stop codons in a KANADI transcription factor as well as a protein kinase. Results from protoplast transient expression assays suggested that each of the polymorphisms conferred allelic differences in the activation of cellulose, hemicelluloses, and lignin pathway marker genes. Conclusion This study illustrates the utility of complementary QTL and association mapping as tools for gene discovery with no a priori candidate gene selection. This proof of concept in a perennial organism opens up opportunities for discovery of novel genetic determinants of economically important but complex traits in plants. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1215-z) contains supplementary material, which is available to authorized users.