Norway spruce
not annotated - annotated - LINNAEUS only
21054436
Gene expression changes during short day induced terminal bud formation in Norway spruce.
The molecular basis for terminal bud formation in autumn is not well understood in conifers. By combining suppression subtractive hybridization and monitoring of gene expression by qRT-PCR analysis, we aimed to identify genes involved in photoperiodic control of growth cessation and bud set in Norway spruce. Close to 1400 ESTs were generated and their functional distribution differed between short day (SD-12 h photoperiod) and long day (LD-24 h photoperiod) libraries. Many genes with putative roles in protection against stress appeared differentially regulated under SD and LD, and also differed in transcript levels between 6 and 20 SDs. Of these, PaTFL1(TERMINAL FLOWER LIKE 1) showed strongly increased transcript levels at 6 SDs. PaCCCH(CCCH-TYPE ZINC FINGER) and PaCBF2&3(C-REPEAT BINDING FACTOR 2&3) showed a later response at 20 SDs, with increased and decreased transcript levels, respectively. For rhythmically expressed genes such as CBFs, such differences might represent a phase shift in peak expression, but might also suggest a putative role in response to SD. Multivariate analyses revealed strong differences in gene expression between LD, 6 SD and 20 SD. The robustness of the gene expression patterns was verified in 6 families differing in bud-set timing under natural light with gradually decreasing photoperiod.
21054435
Seasonal dynamics in the stable carbon isotope composition delta^1^3C from non-leafy branch, trunk and coarse root CO2 efflux of adult deciduous (Fagus sylvatica) and evergreen (Picea abies) trees.
Respiration is a substantial driver of carbon (C) flux in forest ecosystems and stable C isotopes provide an excellent tool for its investigation. We studied seasonal dynamics in delta^1^3C of CO2 efflux (delta^1^3C(E)) from non-leafy branches, upper and lower trunks and coarse roots of adult trees, comparing deciduous Fagus sylvatica (European beech) with evergreen Picea abies (Norway spruce). In both species, we observed strong and similar seasonal dynamics in the delta^1^3C(E) of above-ground plant components, whereas delta^1^3C(E) of coarse roots was rather stable. During summer, delta^1^3C(E) of trunks was about -28.2% (Beech) and -26.8% (Spruce). During winter dormancy, delta^1^3C(E) increased by 5.6-9.1%. The observed dynamics are likely related to a switch from growth to starch accumulation during fall and remobilization of starch, low TCA cycle activity and accumulation of malate by PEPc during winter. The seasonal delta^1^3C(E) pattern of branches of Beech and upper trunks of Spruce was less variable, probably because these organs were additionally supplied by winter photosynthesis. In view of our results and pervious studies, we conclude that the pronounced increases in delta^1^3C(E) of trunks during the winter results from interrupted access to recent photosynthates.
20840508
Hydraulic constraints limit height growth in trees at high altitude.
* Low temperatures limit the fixation of photosynthates and xylogenesis. Here, we hypothesized that reduced longitudinal growth in trees at high altitude is related to the lower hydraulic efficiency of the transport system. * Apical buds of Norway spruce (Picea abies) trees at high and low elevation were heated during 2006 and 2007. At the end of the experiment, trees were felled. Longitudinal increments and tracheid lumen areas were measured along the stem. Apical hydraulic conductivity (k) was estimated from anatomical data. * Before heating, high-altitude trees showed fewer (P = 0.002) and smaller (P = 0.008) apical conduits, and therefore reduced k (P = 0.016) and stem elongation (P < 0.0001), in comparison with trees at low elevation. After 2 yr of heating, k increased at both high (P = 0.014) and low (P = 0.047) elevation. Only high-altitude trees showed increased stem elongation, which reached the same magnitude as that of controls at low elevation (P = 0.735). Heating around the apical shoots did not appear to induce significant changes in conduit dimension along the rest of the stem. * The total number and size of xylem elements at the stem apex are strongly constrained by low temperatures. Trees at high altitude are therefore prevented from building up an efficient transport system, and their reduced longitudinal growth reflects strong hydraulic limitations.