The age and genetics of individual larches in four rural parks and at the Järvselja Educational and Experimental Forest Centre in Estonia

This paper compares the resistance of 20 commercial transparent and semi-transparent coatings applied to European and Siberian larch during artificial weathering in Xenotest. The change in gloss, colour, contact angle of wetting, resistance to Aspergillus niger and Penicillium brevicompactum moulds was evaluated, and visual changes at the top surface of treated wood species were measured. Overall, the durability of coatings on European larch was higher than that on Siberian larch. The most durable of the tested coatings was a thin-film, i.e., semi-transparent oil-based film containing TiO2 pigment and propiconazole fungicide. Of the transparent coatings, the most stable was a thick acrylic coating. Conversely, penetrating transparent oil systems had low colour stability and overall lifespan. Artificial weathering of all of the coatings resulted in a marked decrease in their resistance to moulds.

The composition of extractive substances extracted by petroleum ether from the woody greens of Siberian larch (Larix sibirica Ldb.) and European (Larix decidua Mill.) is presented. The woody greens of Siberian larch contain 2 times more resins (9.5%, here and further % from dry raw materials), than the woody greenery of European larch (5.2%). The alcohol fraction from Larix sibirica made up one quarter of neutral substances (25.6%), which is 2 times higher than in Larix decidua (12.85%). The fraction of diols (30.0% of the amount of alcohols) prevailed in Larix decidua, which is 3.3 times higher than in Larix sibirica. The composition of alcohols of neutral substances is different in two types of larch. Monoterpene alcohols prevailed in Larix decidua (7.0%, hereafter % of the alcohol fraction), the main components – borneol and α-terpineol. The ratio of sesquiterpene components is almost the same in both studied species of larch. In woody greens Larix sibirica major sesquiterpenoids are T-murolol and δ-cadinol, and in Larix decidua – T-cadinol, T-murolol and δ-cadinol. The main fraction of alcohols of neutral substances consisted of diterpenoids (54.3–72.0%). Aromatic diterpene alcohol – dehydroabietinol (23.5%) prevailed in the woody greens of Larix decidua, and in the woody greens of Larix sibirica its oxidized form in the form of methyl ether – 15-hydroxymethyl dehydroabietate (23.1%). Labdanoid 13-epimanool was isolated from woody greens of Larix sibirica (8.0%). Acyclic alcohol phytol was contained in both studied samples of woody greens with 2-fold dominance in Larix decidua. Tricyclic terpenoids levopimarinol and palustrol have been identified only in the woody greens of Larix decidua. The composition of alcohols identified nor-diterpenoids – 18-norisopimarinol and 18-nordehydroabietinol with the predominance of the latter in Larix sibirica. Epitorulosol and its acetate were isolated from the woody greens of Larix sibirica, and larixol was isolated from the woody greens of Larix decidua. The structures of the isolated compounds were confirmed by NMR-spectroscopy.

Larch (Larix) species and hybrids are important conifers that are grown for lumber, poles and pulp as well as ornamental purposes in northern temperate zone forests across North America, Europe and Asia. Among the principal commercial larch species are tamarack (Larix laricina), Western larch (L. occidentalis), European larch (L. decidua), Japanese larch (L. leptolepis), Dahurian larch (L. gmelinii) and Siberian larch (L. siberica). Hybrid larches have shown heterosis in growth, stem form and wood mechanical properties as compared to the parental plants [36].

An optimized method of headspace solid-phase microextraction coupled with gas chromatography with flame ionization detector (HS/SPME-GC/FID) was used to discriminate between larch wood originated from Central Europe and larch wood from Siberia. Variability in the composition of volatile organic compounds (VOC) between both larches were found, as well as in intensities of volatiles in chromatograms. These differences are influenced by many factors like genetic, environmental and spatial factors. Therefore, the optimized method was used to measure VOC fingerprints of 82 samples of European and Siberian larches. The VOC fingerprints have been characterized by calculation of retention indices for each compound. The statistical evaluation of the retention indices obtained from VOC fingerprints was performed using multivariate regression with a reduction in dimensionality-orthogonal projections to latent structure (OPLS). Such approach was able to discriminate the correct origin of all 82 larch wood samples. Hence, analysis of VOC fingerprints using HS/SPME-GC/FID in combination with OPLS presents a useful tool for discrimination between wood of European larch and Siberian larch. By extending this method to other species and factors of influence, it might be of great interest for wood certification and forestry industry.

Background and objectivesPhytophthora ramorum severely affects both European larch (EL) and Japanese larch (JL) trees as indicated by high levels of mortality particularly in the UK. Field observations suggested that EL is less severely affected and so may be less susceptible to P. ramorum than JL; however, controlled inoculations have produced inconsistent or non-statistically significant differences. The present study aimed to compare RNA transcript accumulation profiles in EL and JL in response to inoculation with P. ramorum to improve our understanding of their defence responses.MethodologyRNA-sequencing was carried out on bark tissues following the inoculation with P. ramorum of potted saplings in both EL and JL carried out under controlled environment conditions, with sampling at 1, 3, 10, and 25 days post inoculation in infected and control plants.ResultsAll of the inoculated trees rapidly developed lesions but no statistically significant differences were found in lesion lengths between EL and JL. RNA-Sequencing comparing control and inoculate saplings identified key differences in differentially expressed genes (DEGs) between the two larch species. European larch had rapid induction of defence genes within 24 hours of infection followed by sustained expression until 25 days after inoculation. Results in JL were more varied; upregulation was stronger but more transient and represented fewer defence pathways. Gene enrichment analyses highlighted differences in jasmonate signalling and regulation including NPR1 upregulation in EL only, and specific aspects of secondary metabolism. Some DEGs were represented by multiple responsive copies including lipoxygenase, chalcone synthase and nucleotide-binding, leucine-rich-repeat genes.ConclusionThe variations between EL and JL in responsive DEGs of interest as potentially related to differences seen in the field and should be considered in the selection of trees for planting and future breeding.

Hybrid larch (Larix decidua x L.kaempferi) is a fast growing species with high potential for reforestation outside the native range of European larch. Its superiority over its parents is well documented but still today little is known about the genetic background of heterosis and even less about the physiological mechanisms supporting it. In this paper, we hypothesize that a different allocation of biomass and/or growth efficiency could explain growth differences between larch species. To examine heterosis sensu stricto, we used a subset of progeny from an intra−/inter-specific diallel-mating design represented by connected pedigrees from the three species (Hybrid larch, European larch and Japanese larch). Six years after planting, we harvested the trees, excavated roots and measured dry weights of above- and belowground parts. The best allometric relationships were determined for predicting the biomass of each compartment. Heterosis for stem volume exceeded 108 per cent and 81 per cent for total tree biomass over mid-parent values. Hybrid superiority was visible for all biomass compartments and particularly for needles and branches, so that aboveground biomass heterosis reached 2.5 times that for the roots. In addition to a greater biomass, the hybrid benefited from a modified allocation of biomass with a slightly higher proportion of branch and needle biomasses and a reduced proportion of root biomass. Hybrid and European larches had a significantly greater growth efficiency than Japanese larch. Whereas the differential of productivity between European and Japanese larch did not increase with size, it greatly increased for hybrids with fine root mass increase. A heavier crown, a reduced proportion of root biomass and greater root efficiency in hybrid larch should enhance photosynthesis and reduce root respiration cost, providing more carbon-based resources for use in stem wood production. Implications for breeding are briefly discussed.

BackgroundThe main objectives of this study were sequencing, assembling, and annotation of chloroplast genome of one of the main Siberian boreal forest tree conifer species Siberian larch (Larix sibirica Ledeb.) and detection of polymorphic genetic markers – microsatellite loci or simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs).ResultsWe used the data of the whole genome sequencing of three Siberian larch trees from different regions - the Urals, Krasnoyarsk, and Khakassia, respectively. Sequence reads were obtained using the Illumina HiSeq2000 in the Laboratory of Forest Genomics at the Genome Research and Education Center of the Siberian Federal University. The assembling was done using the Bowtie2 mapping program and the SPAdes genomic assembler. The genome annotation was performed using the RAST service. We used the GMATo program for the SSRs search, and the Bowtie2 and UGENE programs for the SNPs detection. Length of the assembled chloroplast genome was 122,561 bp, which is similar to 122,474 bp in the closely related European larch (Larix decidua Mill.). As a result of annotation and comparison of the data with the existing data available only for three larch species - L. decidua, L. potaninii var. chinensis (complete genome 122,492 bp), and L. occidentalis (partial genome of 119,680 bp), we identified 110 genes, 34 of which represented tRNA, 4 rRNA, and 72 protein-coding genes. In total, 13 SNPs were detected; two of them were in the tRNA-Arg and Cell division protein FtsH genes, respectively. In addition, 23 SSR loci were identified.ConclusionsThe complete chloroplast genome sequence was obtained for Siberian larch for the first time. The reference complete chloroplast genomes, such as one described here, would greatly help in the chloroplast resequencing and search for additional genetic markers using population samples. The results of this research will be useful for further phylogenetic and gene flow studies in conifers.

From 1989 to 1993, trunk implants of acephate were tested for the control of seed and cone insect damage to conifer species in France and northeastern China. The treatments were promising for the control of the major pests that feed on cone and seed tissues, including cone flies, coneworms, and seedworms, in European and Siberian larch, Norway spruce, Scots and mountain pine. In contrast, acephate implants did not prevent seed chalcid damage nor that of gall midges in Douglas-fir, European larch, and Siberian larch. Treatment generally increased seed yield, but a significant increase in the number of filled seeds was seen only when chalcids and midges were absent. The 2-year effect of implants seemed limited. Acephate implantation did not seem to affect seed germination.

Genetic markers from the nuclear, chloroplast, and mitochondrial genomes were developed to distinguish unambiguously among four larch species [Larix laricina (Du Roi) K. Koch, Larix decidua (Mill.), Larix kaempferi (Lamb.) Sarg., and Larix sibirica (Ledeb.)] used in intensive forestry in eastern North America. Nine random amplified polymorphic DNA (RAPD) fragments had good diagnostic value, and 3 out of 12 nuclear genes were found to harbor fixed interspecific polymorphisms implicating a total of 17 single nucleotide polymorphisms (SNPs) and 2 indels. The sequencing of five mtDNA introns (cox1-intron1, matR-intron1, nad1-intron b/c, nad3-intron1, and nad5-intron1) and four cpDNA regions (matK, trnL-intron, trnT–trnL and trnL–trnF intergenic spacers) resulted in the identification of 14 sites with fixed interspecific differences among the four species. Including the ten Larix species, one polymorphic site per 47 nucleotide sites sampled was observed for nuclear genes, one per 283 sites for cpDNA, and one per 374 sites for mtDNA. The phylogeny of the genus could be estimated from variation among the ten species detected in two cpDNA intergenic regions and four mtDNA introns. There was congruence between cpDNA and mtDNA phylogenies with three large groups delineated: the North American, North Eurasian, and South Asian taxa. The position of L. sibirica differed between organelle genomes. It was regrouped with South Asian species on the cpDNA tree, but with its North Eurasian congenerics on the mtDNA tree. To simplify the detection of diagnostic DNA sequence polymorphisms among the four main Larix species, cleaved amplified polymorphic sequence (CAPS) assays were developed from the polymorphisms identified in the various genomes. Seventeen primer–enzyme combinations were tested, and six were selected for their high level of informativeness. These new species-specific diagnostic markers should be useful for the certification of larch breeding materials and hybrid stocks used in intensive forestry in the northern hemisphere.

The paper presents the results of studying morphological characteristics and sowing qualities of seeds of larch species introduced to the center of European Russia (Larix sibirica Ledeb., L. sukaczewii Dyl., L. decidua Mill., L. marschlinsii Coaz, L. olgensis A. Henry, L. principis-rupprechtii Mayr, L. kaempferi (Lamb.) Carriere, L. laricina (Du Roi) K. Koch). The research was carried out in Moscow (Main Botanical Garden of the Russian Academy of Sciences) and the Moscow region (Ivanteevsky Dendrological Garden, Yegoryevsky phosphorite deposit). This topic is urgent since determination of seed germination and viability is essential for introduction, whereas there are no recommendations for American larch and Prince Rupprecht’s larch in the State Standards (GOST) for determination of sowing qualities and quality class of seeds. The data on the variability of morphological characteristics of seeds of different larch species presented in the paper allow revealing their biological features under introduction conditions, which can be the basis for expanding the use of the studied plants in the center of European Russia. The individual variability of seed length and width, the relationship of these characteristics, as well as germination energy, germination, viability, and seed quality class were considered. Olga Bay larch has substandard seeds. Seeds of other larch species (Siberian, Sukachev’s, European, Margilind, Prince Rupprecht’s, Japanese and American larches) belong to the 2nd and 3rd quality classes. It allows recommending these species for sowing. Siberian larch growing on the Yegoryevsky phosphorite deposit showed a decrease in the sowing qualities of seeds (compared to the species from the Main Botanical Garden of the Russian Academy of Sciences) and the absence of relationship of seed length and width (compared to other objects of the research). Correlation analysis showed differences in linear and curvilinear relationships of seed length and width in Siberian and Sukachev’s larches, as well as in Margilind larch and its parental species (European and Japanese larches).

Thirteen populations ofLarix decidua subsp.decidua and subsp.polonica, and three populations ofL. sibirica were investigated by starch-gel electrophoresis. In the populations assayed 61 alleles at 17 loci were revealed. The allozyme data support the earlier observations about close relationships between these two larch species. Nei's genetic distances betweenL. decidua andL. sibirica were relatively small (D = 0.057), however, almost five times larger, on average, than those between populations of the same species. Results obtained in this study disagree withBobrov's hypothesis about the hybrid origin of the Polish larch and suggest a direct origin from the European larch.

Species-specific RAPD markers were used to identify the different larch species (Larix decidua and Larix kaempferi) and their interspecific hybrid (Larix X eurolepis). Although morphological differences between pure species and the hybrids exist, differentiation is not always possible, especially at an early stage (seed or plantlet). Eleven RAPD markers differentiated the two larch species, and 4 species-specific markers were sufficient to estimate the F1 hybrid fraction in a seed lot. The species-specific markers were tested on individual trees of European and Japanese larches of diverse geographic origins and on several seed lots of different origins (F1, F2 hybrids and pure species). The 4 specific markers found for the European larch and the Japanese larch were monomorphic and present in all provenances and in all F1 hybrid trees tested. Polymorphic SCAR fragments were obtained for 3 of the 11 fragments originally selected for the RAPD screening phase. For 2 of them, the sequence had some homology with the mitochondrial genome of other organisms and is thus mitochondrial. The two mitochondrial fragments and the OPF-131000 fragment exhibited one polymorphic band, thereby maintaining its species-specific identity: OPF-131000 is specific to the European larch. The 4 RAPD primers selected in this study offer a reliable, quick and cheap tool for the identification of different larch species (Larix decidua and Larix kaempferi) and their interspecific hybrid (Larix X eurolepis).

The results of the cultivation of Scots pine (Pinus sylvestris L.) in the provenance trial in the Serebryanoborsky experimental forest district of the Institute of Forestry of the Russian Academy of Sciences are summarized. The silvicultural effect was assessed by a comprehensive indicator of the feasibility of introducing specific pine conventions. It was established that the use of pine seeds of exclusively local provenances cannot be considered justified. In the vast area of pine there are very remote populations of a local nature, the seed of which, when moved, can be successfully used to create highly productive artificial stands. The 68 year old geographical plantations of larch growth and production rates of 18 climotypes of 14 larch species were compared. These species are Polish larch (Larix polonica Racib.), European larch (Larix decidua Mill. f. Sudetica), Larix sukaczewii Dylis, Siberian larch (Larix sibirika Ledeb.), Larix cajanderi Mayr., Larix gmelinii Rupr., Larix Czekanovskii Szaf, Larix amurensis Kolesn., Olgan larch (Larix olgensis Henry), Japanese larch (Larix kaempferi (Lamb.) Carrière), Larix kurilensis Maur., Larix principis Rupprechtii Maur., Larix potaninii Bat, American larch (Larix laricina (Duroi) K. Koch). Polish larch, Japanese larch, European larch and Olgan larch have the best growth rate results. Climotypes from Siberia and American larch showed worst results. Polish larch (812 m3/ha) and Japanese (804 m3/ha) larch from the Southern Sakhalin have the highest stem volume. The final estimations showed that the climotypes of Polish larch, European larch from Sudetes and Japanese larch from the Southern Sakhalin are suitable for introduction in the Moscow Region. The climotypes from the Far East, namely Larix amurensis Kolesn., Olgan larch and Larix kurilensis Maur., had positive silvicultural effect. The inland climotypes from Asia together with American larch showed negative results.

A new distribution map is provided for Cephalcia lariciphila (Wachtl). Hymenoptera: Pamphiliidae. Hosts: common larch ( Larix decidua ), Siberian larch ( L. sibirica ), Japanese larch ( L. kaempferi ) and hybrid larch ( L. marschlinsii ). Information is given on the geographical distribution in Europe (Austria, Belgium, Czech Republic, Denmark, France, Mainland France, Germany, Italy, Mainland Italy, Netherlands, Portugal, Russia, Eastern Siberia, European Russia, Western Siberia, Sweden, Switzerland, UK, England and Wales, Northern Ireland, Scotland), Asia (Japan, Hokkaido).

Quantifying ozone uptake at the canopy level of spruce, pine and larch trees at the alpine timberline: an approach based on sap flow measurement