Epigenetic memory effects in Norway spruce: are they present after the age of two years?

Short-term trials on cultivated soil were planted with families of Norway spruce that had shown epigenetic memory effects in early tests up to age two years. Measurements and assessments were made of phenology traits, tree heights and stem defects until age 16 years in these trials. The memory effects of the temperature conditions during embryo development and seed maturation were confirmed for the timing of bud flush and for start and cessation of shoot elongation at age six years. The mean differences in timing of these events caused by temperature treatments were on average less than two days. They were considerably larger for families with strong effects on terminal bud set at the end of the first growing season. The memory effects did not result in a prolonged shoot growth period, nor did they affect height growth. Interaction effects expressed in adaptive traits between factorial treatments of temperature and daylength during seed production were large in the short-term trial and were still present at age nine years. The results presented demonstrate that strong memory effects observed in early tests may also be expressed in phenology traits for at least the next five growing seasons.acceptedVersio

State of Forest Genetic Resources in Norway

Forests and wooded land cover 39 % of the land area of Norway and productive forest amounts to 8.3 million hectares. Two conifer species, Picea abies and Pinus sylvestris, dominate the forest area; they cover 71 % of the forest area and 84 % of total volume. The annual harvest is at present less than 50 % of the annual increment. Forestry and the wood industry have great financial importance in Norway, and timber and wood products have a gross value of 5 % of the total gross domestic product. Forestry is characterized by small-scale properties which to a large extent are privately owned. The main objective of the forest policy is to promote sustainable forest management with a view to promote active, local and economic development, and to secure biological diversity, considerations for the landscape, outdoor recreation and the cultural values associated with the forest. Forest management plans are important instruments to obtain these goals. Three targeted programmes have high priority in the present forest policy: forests and climate, increased use of wood and bioenergy. Active use of the forest genetic resources may contribute to the success of these programmes. Species composition and distribution of forest trees in Norway is largely determined by the following factors: the invasion of tree species after the Ice Age, subsequent climatic changes and human activities ....publishedVersio

Field trial performance of Norway spruce families from Opsahl Seed Orchard

Field trials with Norway spruce seedlings from 84 full-sib families from a factorial cross in Opsahl Seed Orchard and 11 provenances were planted at eight sites between altitudes between 600 and 900 m in Oppland County in Norway. Measurements of tree heights and assessments of stem and branch defects were made at regular intervals until 34 years from seed. Data from measurements made in nursery trials and from artificial freezing trials were also available. The families from the seed orchard had on average 12 % better height growth than the provenances. For volume growth per hectare, measured in two of the trials 30 years after planting, the families had a superiority of more than 30 %. A large variation among families was present for height growth and additive genetic variation was the main genetic factor. For the maternal half-sib families, the ranking of families for height was stable after 15 years from seed, and the five best families selected for height at that age were at age 34 years 6 % taller and produced 13 % more volume per hectare compared with the mean of all families. Weak relationships were present between traits measured in the nursery trial, the freezing test and the field trials. Assessments were made of cone production at age 20 years after planting and showed variation among families for the frequency of trees with cones.Field trial performance of Norway spruce families from Opsahl Seed OrchardpublishedVersio

Weak relationships between injuries in freezing tests and performance in short-term and field trials of Norway spruce families from Stange Seed Orchard

Artificial freezing tests were performed on seedlings from Norway spruce families at the end of the first growing season. Similar tests were made on twigs collected from trees in a progeny test at the end of growing season nine. The 26 families in the early test were included in the short-term progeny test with 100 full-sib families from a 10 x 10 factorial cross. All families were also planted in seven field trials in Norway, Sweden and Finland, from which data on mortality, tree heights and stem damage at age 10 years are available. Significant difference was found among families for freezing test injuries on whole intact seedlings at the end of the first growing season and for lethal temperature of needles on detached twigs collected at the end of growing season nine. However, no relationships were found between the freezing test scores of families in the two types of tests or few between these scores and the traits measured in the short-term and field trials. The results show that frost hardiness testing of families at a young age, grown under artificial temperature and light conditions in nursery, is a weak predictor of their performance under natural conditions in field at older ages.Weak relationships between injuries in freezing tests and performance in short-term and field trials of Norway spruce families from Stange Seed OrchardWeak relationships between injuries in freezing tests and performance in short-term and field trials of Norway spruce families from Stange Seed OrchardpublishedVersio

Genetisk variasjon i norske skogtrær – en oversikt over publiserte studier (1954-2019)

Denne rapporten gir en kortfattet oversikt over publiserte arbeider vedrørende studier av genetisk variasjon i norske skogtrær. Her er bare tatt med originale arbeider som karakteriserer genetisk variasjon og genetiske prosesser som påvirker variasjonen. Arbeider som kun beskriver metodikk og teknikker er utelatt.publishedVersio

Epigenetic regulation of adaptive responses of forest tree species to the environment

Epigenetic variation is likely to contribute to the phenotypic plasticity and adaptative capacity of plant species, and may be especially important for long-lived organisms with complex life cycles, including forest trees. Diverse environmental stresses and hybridization/polyploidization events can create reversible heritable epigenetic marks that can be transmitted to subsequent generations as a form of molecular “memory”. Epigenetic changes might also contribute to the ability of plants to colonize or persist in variable environments. In this review, we provide an overview of recent data on epigenetic mechanisms involved in developmental processes and responses to environmental cues in plant, with a focus on forest tree species. We consider the possible role of forest tree epigenetics as a new source of adaptive traits in plant breeding, biotechnology, and ecosystem conservation under rapid climate chang

Does maternal environmental condition during reproductive development induce genotypic selection in Picea abies ?

In forest trees, environmental conditions during reproduction can greatly influence progeny performance. This phenomenon probably results from adaptive phenotypic plasticity but also may be associated with genotypic selection. In order to determine whether selective effects during the reproduction are environment specific, single pair-crosses of Norway spruce were studied in two contrasted maternal environments (warm and cold conditions). One family expressed large and the other small phenotypic differences between these crossing environments. The inheritance of genetic polymorphism was analysed at the seed stage. Four parental genetic maps covering 66 to 78% of the genome were constructed using 190 to 200 loci. After correcting for multiple testing, there is no evidence of locus under strong and repeatable selection. The maternal environment could thus only induce limited genotypic-selection effects during reproductive steps, and performance of progenies may be mainly affected by a long-lasting epigenetic memory regulated by temperature and photoperiod prevailing during seed productio

Do maternal environmental conditions during reproductive development induce genotypic selection in Picea abies?

In forest trees, environmental conditions during reproduction can greatly influence progeny performance. This phenomenon probably results from adaptive phenotypic plasticity but also may be associated with genotypic selection. In order to determine whether selective effects during the reproduction are environment specific, single pair-crosses of Norway spruce were studied in two contrasted maternal environments (warm and cold conditions). One family expressed large and the other small phenotypic differences between these crossing environments. The inheritance of genetic polymorphism was analysed at the seed stage. Four parental genetic maps covering 66 to 78% of the genome were constructed using 190 to 200 loci. After correcting for multiple testing, there is no evidence of locus under strong and repeatable selection. The maternal environment could thus only induce limited genotypic-selection effects during reproductive steps, and performance of progenies may be mainly affected by a long-lasting epigenetic memory regulated by temperature and photoperiod prevailing during seed production.L'environnement maternel induit-il une sélection génotypique durant les différents stades de reproduction chez Picea abies ?. Chez les arbres forestiers, les conditions environnementales durant la reproduction peuvent influencer les performances des descendants. Ce phénomène reflète probablement la plasticité phénotypique, mais également il pourrait être associé à une sélection génotypique. Afin de déterminer si des effets sélectifs durant la reproduction sont spécifiques d'un environnement donné, deux familles d'épicéa commun non apparentées ont été obtenues par croisements dirigés dans deux environnements maternels contrastés (conditions chaude et froide). La première famille exprimait de larges différences phénotypiques entre les deux environnements tandis que la seconde ne montrait pas de différence significative. La transmission des polymorphismes génétiques a été étudiée au stade de la graine. Quatre cartes génétiques parentales couvrant 66 à 78 % du génome ont été construites. Aucun effet de sélection n'a été mis en évidence aux différents locus étudiés. L'environnement maternel n'induirait donc que des effets de sélection génotypique relativement faibles durant les stades de la reproduction. Les performances des descendants seraient principalement affectées par une mémoire épigénétique durable régulée par la température et la photopériode régnant durant la production des graines