| 1. |
- Goodwillie, Carol, et al.
(författare)
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Correlated evolution of mating system and floral display traits in flowering plants and its implications for the distribution of mating system variation
- 2010
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 185, s. 311-321
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Tidskriftsartikel (refereegranskat)abstract
- New Phytologist (2009) Reduced allocation to structures for pollinator attraction is predicted in selfing species. We explored the association between outcrossing and floral display in a broad sample of angiosperms. We used the demonstrated relationship to test for bias against selfing species in the outcrossing rate distribution, the shape of which has relevance for the stability of mixed mating. Relationships between outcrossing rate, flower size, flower number and floral display, measured as the product of flower size and number, were examined using phylogenetically independent contrasts. The distribution of floral displays among species in the outcrossing rate database was compared with that of a random sample of the same flora. The outcrossing rate was positively associated with the product of flower size and number; individually, components of display were less strongly related to outcrossing. Compared with a random sample, species in the outcrossing rate database showed a deficit of small floral display sizes. We found broad support for reduced allocation to attraction in selfing species. We suggest that covariation between mating systems and total allocation to attraction can explain the deviation from expected trade-offs between flower size and number. Our results suggest a bias against estimating outcrossing rates in the lower half of the distribution, but not specifically against highly selfing species.
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| 2. |
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| 3. |
- Arnebrant, Kristina, et al.
(författare)
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Nitrogen translocation between Alnus glutinosa (L.) Gaertn. seedlings inoculated with Frankia sp and Pinus contorta Doug ex Loud seedlings connected by a common ectomycorrhizal mycelium
- 1993
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 124:2, s. 231-242
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Tidskriftsartikel (refereegranskat)abstract
- Uptake and translocation of nitrogen was studied in laboratory microcosms consisting of Alnus glutinosa (L.) Gaertn., Frankia sp., Paxillus involutus (Fr.) Fr. and Pinus contorta Dougl. ex Loud. P. involutus was shown to form a fully functional ectomycorrhizal association with alder as well as pine, and the seedlings thus became interconnected by a common mycelium. When microcosms were exposed to N-15(2) gas, interplant translocation of N-15 was observed in two out of three experiments. N-15(2) was fixed by Frankia and translocated to all other parts of the system. In the two experiments in which interplant translocation occurred, between 5 and 15 % of the N-15 recovered was found in the pine seedlings. Within seven days, fixed N2 was incorporated into amino acids in the Frankia nodules, translocated to both the A. glutinosa and P. contorta seedlings and incorporated into macromolecules. In alder seedlings, citrulline and ornithine were the free amino acids that had both the highest N-15 enrichment levels and concentrations. In pine, glutamine and citrulline had the highest N-15 concentrations, and glutamine had the highest level of N-15 enrichment. N-15 enrichment levels were greatest in the nodules, at between 5.5 and 29 % in the different amino acids and 12 % in the macromolecular fraction. Enrichment levels decreased with increasing distance from the nodules. The uptake and translocation of N-15 applied as (NH4Cl)-N-15 to the mycelium was also studied. N-15 was incorporated into amino acids in the mycelium and translocated further in this form. Generally, free amino acids had high N-15 enrichment levels in the mycelium, decreasing along the translocation pathway. Citrulline and glutamine were the amino acids with highest N-15 concentrations in all parts of the system. N-15 was also found in the macromolecular fraction.
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| 4. |
- Beerling, D. J., et al.
(författare)
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Leaf metabolic and morphological responses of dwarf willow (Salix herbacea) in the sub-arctic to the past 9000 years of global environmental change
- 2000
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 145:2, s. 257-269
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Tidskriftsartikel (refereegranskat)abstract
- Ice-core records of the concentration of atmospheric CO2 and its stable isotope ratio (δ13C(a)) have shown that the global C cycle has not remained in steady-state over the past 11000 yr, implying a possible change in vegetation activity over this period. Here we evaluated the ecophysiological responses of the dwarf willow (Salix herbacea) over the past 9000 yr by measuring the stable carbon isotope composition and stomatal characters of a unique, well dated, high-latitude (68°N) sub-fossil leaf sequence. After correction for corresponding changes in δ13C(a), 9000-yr record of variations in the ratio of intercellular (c(j)) to atmospheric (c(a)) CO2 concentration was established. Intercellular: atmospheric CO2 concentration ratios provide a time-integrated indicator of the set-point of leaf gas exchange, and the historical variations revealed in this record have been interpreted as an impact of environmental changes on leaf gas exchange. The sequence shows a progressive fall in c(i)/c(a) 9000-3000 yr BP as well as the climatic effects of the Medieval Warm Period, the Little Ice Age and the post-industrial CO2 rise. Leaf stomatal index (proportion of epidermal cells as stomata), but not stomatal density, was significantly (P <0.01) correlated with Holocene atmospheric CO2 variations. A process-based interpretation of the changes in c(i)/c(a) was made using two different coupled photosynthesis-stomatal conductance models. Calculated in this way, S. herbacea photosynthetic rates were relatively stable throughout the Holocene whilst stomatal conductance progressively declined. Both, however, showed the marked effects of the Medieval Warm Period and the Little Ice Age. Overall, the results demonstrate that S. herbacea leaf metabolism, like the global C cycle, has not remained in steady state during the Holocene but has responded to changes in atmospheric CO2 concentration and short-term climatic oscillations.
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| 5. |
- Bidartondo, MI, et al.
(författare)
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Do nutrient additions alter carbon sink strength of ectomycorrhizal fungi?
- 2001
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 151:2, s. 543-550
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Tidskriftsartikel (refereegranskat)abstract
- Carbon sink strength differences are examined here between ectomycorrhizal fungi in interaction with additions of ammonium and apatite (a phosphorus- and calcium-containing mineral). Pinus muricata associated with Paxillus involutus and four suilloid isolates (Suillus pungens and members of three Rhizopogon section Amylopogon species groups) were used in microcosm nutrient addition experiments. The associations differed in ectomycorrhizal biomass, mycelial growth rate, biomass and respiration. P. involutus produced the lowest biomass of ectomycorrhizal connections to P. muricata, but it consumed proportionally more carbon per connection and transferred more than twice as much ammonium to the host per unit mycorrhizal biomass. Paxillus also colonized the soil more rapidly and intensely than the other fungi, but its mycelial respiration was lowest. Ammonium and apatite addition resulted in a marked increase in respiration and mycelial biomass, respectively, by the suilloid fungi. The high carbon cost of ammonium uptake is suggested as one explanation for reduced sporocarp production and mycelial growth by ectomycorrhizal fungi commonly found after high levels of nitrogen addition.
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| 6. |
- Bordallo, JJ, et al.
(författare)
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Colonization of plant roots by egg-parasitic and nematode-trapping fungi
- 2002
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 154:2, s. 491-499
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Tidskriftsartikel (refereegranskat)abstract
- • The ability of the nematode-trapping fungus Arthrobotrys oligospora and the nematode egg parasite Verticillium chlamydosporium to colonize barley (Hordeum vulgare) and tomato (Lycopersicum esculentum) roots was examined, together with capability of the fungi to induce cell wall modifications in root cells. • Chemotropism was studied using an agar plate technique. Root colonization was investigated with light microscopy and scanning electron microscopy, while compounds involved in fungus–plant interactions were studied histochemically. • Only A. oligospora responded chemotropically to roots. Colonization of barley and tomato by both fungi involved appressoria to facilitate epidermis penetration. V. chlamydosporium colonized tomato root epidermis and produced chlamydospores. Papillae, appositions and lignitubers ensheathing hyphae on tomato were also found. Phenolics (including lignin), protein deposits and callose were present in papillae in both hosts. Both fungi were still present in epidermal cells 3 months after inoculation. • Nematophagous fungi colonized endophytically monocotyledon and dicotyledon plant roots. Arthrobotrys oligospora seemed to be more aggressive than V. chlamydosporium on barley roots. Both fungi induced cell wall modifications, but these did not prevent growth. The response of root cells to colonization by nematophagous fungi may have profound implications in the performance of these organisms as biocontrol agents of plant parasitic nematodes.
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| 7. |
- Ekman, Åsa, et al.
(författare)
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Elevated atmospheric CO2 concentration and diurnal cycle induce changes in lipid composition in Arabidopsis thaliana
- 2007
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 174:3, s. 591-599
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Tidskriftsartikel (refereegranskat)abstract
- Few studies regarding the effects of elevated atmospheric CO2 concentrations on plant lipid metabolism have been carried out. Here, the effects of elevated CO2 concentration on lipid composition in mature seeds and in leaves during the diurnal cycle of Arabidopsis thaliana were investigated. Plants were grown in controlled climate chambers at elevated (800 ppm) and ambient CO2 concentrations. Lipids were extracted and characterized using thin layer chromatography (TLC) and gas liquid chromatography. The fatty acid profile of total leaf lipids showed large diurnal variations. However, the elevated CO2 concentration did not induce any significant differences in the diurnal pattern compared with the ambient concentration. The major chloroplast lipids monogalactosyldiacylglycerol (MGDG) and phosphatidylglycerol (PG) were decreased at elevated CO2 in favour of phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Elevated CO2 produced a 25% lower ratio of 16:1trans to 16:0 in PG compared with the ambient concentration. With good nutrient supply, growth at elevated CO2 did not significantly affect single seed weight, total seed mass, oil yield per seed, or the fatty acid profile of the seeds. This study has shown that elevated CO2 induced changes in leaf lipid composition in A. thaliana, whereas seed lipids were unaffected.
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| 8. |
- Florez-Sarasa, Igor, et al.
(författare)
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Light-responsive metabolite and transcript levels are maintained following a dark-adaptation period in leaves of Arabidopsis thaliana.
- 2012
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 195:1, s. 136-148
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Tidskriftsartikel (refereegranskat)abstract
- The effect of previous light conditions on metabolite and transcript levels was investigated in leaves of Arabidopsis thaliana during illumination and after light-enhanced dark respiration (LEDR), when dark respiration was measured. • Primary carbon metabolites and the expression of light-responsive respiratory genes were determined in A. thaliana leaves before and after 30 min of darkness following different light conditions. In addition, metabolite levels were determined in the middle of the night and the in vivo activities of cytochrome and alternative respiratory pathways were determined by oxygen isotope fractionation. • A large number of metabolites were increased in leaves of plants growing in or transiently exposed to higher light intensities. Transcript levels of respiratory genes were also increased after high light treatment. For the majority of the light-induced metabolites and transcripts, the levels were maintained after 30 min of darkness, where higher and persistent respiratory activities were also observed. The levels of many metabolites were lower at night than after 30 min of darkness imposed in the day, but respiratory activities remained similar. • The results obtained suggest that 'dark' respiration measurements, as usually performed, are probably made under conditions in which the overall status of metabolites is strongly influenced by the previous light conditions.
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| 9. |
- Hunt, L, et al.
(författare)
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Gene-specific expression and calcium activation of Arabidopsis thaliana phospholipase C isoforms
- 2004
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 162:3, s. 643-654
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Tidskriftsartikel (refereegranskat)abstract
- PI-PLCs synthesise the calcium releasing second messenger IP3. We investigated the expression patterns of the Arabidopsis PI-PLC gene family and measured in vitro activity of encoded enzymes. Gene specific RT-PCR and promoter-GUS fusions were used to analyse AtPLC gene expression patterns. The five available AtPLC cDNAs were expressed as fusion proteins in Escherichia coli. All members of the AtPLC gene family were expressed in multiple organs of the plant. AtPLC1, and AtPLC5 expression was localized to the vascular cells of roots and leaves with AtPLC5::GUS also detected in the guard cells. AtPLC4::GUS was detected in pollen and cells of the stigma surface. In seedlings, AtPLC2 and AtPLC3 were constitutively expressed, while AtPLCs 1, 4 and 5 were induced by abiotic stresses. AtPLC1-5 were all shown to have phospholipase C activity in the presence of calcium ions. AtPLCs showed limited tissue specific expression and expression of at least three genes was increased by abiotic stress. The differing calcium sensitivities of recombinant AtPLC protein activities may provide a mechanism for generating calcium signatures.
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| 10. |
- Hyvonen, R., et al.
(författare)
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The likely impact of elevated [CO2], nitrogen deposition, increased temperature and management on carbon sequestration in temperate and boreal forest ecosystems: a literature review
- 2007
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Ingår i: New Phytologist. - Cambridge : Wiley. - 0028-646X .- 1469-8137. ; 173:3, s. 463-480
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Forskningsöversikt (refereegranskat)abstract
- Temperate and boreal forest ecosystems contain a large part of the carbon stored on land, in the form of both biomass and soil organic matter. Increasing atmospheric [CO2], increasing temperature, elevated nitrogen deposition and intensified management will change this C store. Well documented single-factor responses of net primary production are: higher photosynthetic rate (the main [CO2] response); increasing length of growing season (the main temperature response); and higher leaf-area index (the main N deposition and partly [CO2] response). Soil organic matter will increase with increasing litter input, although priming may decrease the soil C stock initially, but litter quality effects should be minimal (response to [CO2], N deposition, and temperature); will decrease because of increasing temperature; and will increase because of retardation of decomposition with N deposition, although the rate of decomposition of high-quality litter can be increased and that of low-quality litter decreased. Single-factor responses can be misleading because of interactions between factors, in particular those between N and other factors, and indirect effects such as increased N availability from temperature-induced decomposition. In the long term the strength of feedbacks, for example the increasing demand for N from increased growth, will dominate over short-term responses to single factors. However, management has considerable potential for controlling the C store.
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