Van Langenhove, L., Janssens, I. A., Verryckt, L., Brechet, L., Hartley, I. P., Stahl, C., et al. (2020). Rapid root assimilation of added phosphorus in a lowland tropical rainforest of French Guiana. Soil Biol. Biochem., 140(107646).
Abstract: Tree growth on weathered soils in lowland tropical forests is limited by low phosphorous (P) availability. However, nutrient manupulation experiments do not always increase the P content in these trees, which raises the question whether trees are taking up added P. In French Guianese lowland rainforest, we measured changes in nitrogen (N) and P availability before and up to two months after N and P fertilizer addition, in soils with intact root systems and in soils where roots and mycorrhizal fungi were excluded by root exclusion cylinders. When the root system was excluded, P addition increased P availability to a much greater extent and for a longer time than in soils with an intact root system. Soil N dynamics were unaffected by root presence/absence. These results indicate rapid P uptake, but not N uptake, by tree roots, suggesting a very effective P acquisition process in these lowland rainforests.
Keywords: Fertilization; Nitrogen; Phosphorus; Plant root simulator probes; Root system; Tropical forest; Nitrogen; Nitrogen fertilizers; Phosphorus; Plants (botany); Soils; Tropics; Fertilization; Mycorrhizal fungus; N and P fertilizer; P availabilities; Plant root simulators; Root system; Tropical forest; Tropical rain forest; Forestry; Fungi
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Nixon, S., Agwa, A., Robinson, S., Walker, A., Touchard, A., Schroeder, C., et al. (2020). Discovery and characterisation of novel peptides from Amazonian stinging ant venoms with antiparasitic activity. Toxicon, 177(1), S60.
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Aili, S. R., Touchard, A., Hayward, R., Robinson, S. D., Pineda, S. S., Lalagüe, H., et al. (2020). An integrated proteomic and transcriptomic analysis reveals the venom complexity of the bullet ant Paraponera clavata. Toxins, 12(5).
Abstract: A critical hurdle in ant venom proteomic investigations is the lack of databases to comprehensively and specifically identify the sequence and function of venom proteins and peptides. To resolve this, we used venom gland transcriptomics to generate a sequence database that was used to assign the tandem mass spectrometry (MS) fragmentation spectra of venom peptides and proteins to specific transcripts. This was performed alongside a shotgun liquid chromatography-mass spectrometry (LC-MS/MS) analysis of the venom to confirm that these assigned transcripts were expressed as proteins. Through the combined transcriptomic and proteomic investigation of Paraponera clavata venom, we identified four times the number of proteins previously identified using 2D-PAGE alone. In addition to this, by mining the transcriptomic data, we identified several novel peptide sequences for future pharmacological investigations, some of which conform with inhibitor cysteine knot motifs. These types of peptides have the potential to be developed into pharmaceutical or bioinsecticide peptides. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Keywords: DRG neurons; Hyaluronidase; Neurotoxins; Paraponeritoxin; Phospholipases; Rp-Hplc; alpha latrotoxin; ant venom; arginine kinase; cathepsin; contig; defensin 2; hyaluronidase; icarapin; metalloproteinase; neurotoxin; novel toxin like protein; phospholipase; phospholipase A2; poneratoxin; proteome; serine proteinase; transcriptome; unclassified drug; amino acid sequence; ant; Article; liquid chromatography-mass spectrometry; neurotoxicity; nonhuman; Paraponera clavata; protein expression; proteomics; sequence database; tandem mass spectrometry; transcriptomics; venom gland
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Do, N. A., Dias, D., Zhang, Z., Huang, X., Nguyen, T. T., Pham, V. V., et al. (2020). Study on the behavior of squared and sub-rectangular tunnels using the Hyperstatic Reaction Method. Transp. Geotech., 22(100321).
Keywords: Finite element method; Lining; Squared shape; Sub-rectangular shape; Tunnel; efficiency measurement; finite element method; numerical model; transportation development; transportation planning; tunnel design; tunnel lining
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Levionnois, S., Coste, S., Nicolini, E., Stahl, C., Morel, H., & Heuret, P. (2020). Scaling of petiole anatomies, mechanics and vasculatures with leaf size in the widespread Neotropical pioneer tree species Cecropia obtusa Trécul (Urticaceae). Tree Physiol., 40(2), 245–258.
Abstract: Although the leaf economic spectrum has deepened our understanding of leaf trait variability, little is known about how leaf traits scale with leaf area. This uncertainty has resulted in the assumption that leaf traits should vary by keeping the same pace of variation with increases in leaf area across the leaf size range. We evaluated the scaling of morphological, tissue-surface and vascular traits with overall leaf area, and the functional significance of such scaling. We examined 1,271 leaves for morphological traits, and 124 leaves for anatomical and hydraulic traits, from 38 trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a Neotropical genus of pioneer trees that can exhibit large laminas (0.4 m2 for C. obtusa), with leaf size ranging by two orders of magnitude. We measured (i) tissue fractions within petioles and their second moment of area, (ii) theoretical xylem hydraulic efficiency of petioles and (iii) the extent of leaf vessel widening within the hydraulic path. We found that different scaling of morphological trait variability allows for optimisation of lamina display among larger leaves, especially the positive allometric relationship between lamina area and petiole cross-sectional area. Increasing the fraction of pith is a key factor that increases the geometrical effect of supportive tissues on mechanical rigidity and thereby increases carbon-use efficiency. We found that increasing xylem hydraulic efficiency with vessel size results in lower leaf lamina area: xylem ratios, which also results in potential carbon savings for large leaves. We found that the vessel widening is consistent with hydraulic optimisation models. Leaf size variability modifies scaling of leaf traits in this large-leaved species. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permission@oup.com.
Keywords: allometry; leaf size; petiole anatomy; scaling; theoretical hydraulic conductivity; vessel widening; xylem
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Ntawuhiganayo, E. B., Uwizeye, F. K., Zibera, E., Dusenge, M. E., Ziegler, C., Ntirugulirwa, B., et al. (2020). Traits controlling shade tolerance in tropical montane trees. Tree Physiol., 40(2), 183–197.
Abstract: Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among different tree species. At present, we lack a clear understanding of which plant traits control this variation, e.g., regarding the relative contributions of whole-plant versus leaf traits or structural versus physiological traits. We investigated a broad range of traits in six tropical montane rainforest tree species with different degrees of shade tolerance, grown under three different radiation regimes (under the open sky or beneath sparse or dense canopies). The two distinct shade-tolerant species had higher fractional biomass in leaves and branches while shade-intolerant species invested more into stems, and these differences were greater under low radiation. Leaf respiration and photosynthetic light compensation point did not vary with species shade tolerance, regardless of radiation regime. Leaf temperatures in open plots were markedly higher in shade-tolerant species due to their low transpiration rates and large leaf sizes. Our results suggest that interspecific variation in shade tolerance of tropical montane trees is controlled by species differences in whole-plant biomass allocation strategy rather than by difference in physiological leaf traits determining leaf carbon balance at low radiation. © The Author(s) 2019. Published by Oxford University Press.
Keywords: biomass allocation; leaf temperature; plant traits; Rwanda; shade intolerance; shade tolerance; tropical montane forest; article; biomass allocation; breathing; canopy; carbon balance; compensation; photosynthesis; plant leaf; plant stem; rain forest; Rwanda; shade tolerance; species difference; sweating
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Duplais, C., Papon, N., & Courdavault, V. (2020). Tracking the Origin and Evolution of Plant Metabolites. Trends Plant Sci., 25(12), 1182–1184.
Abstract: Iridoids are monoterpenes that are produced by various plants as chemical defense molecules. Lichman et al. recently described the timeline of molecular events that underpin the re-emergence of iridoid biosynthesis in an independent lineage of aromatic plants (catnip). This study represents a benchmark for studying enzyme and metabolite evolution in different clades across the tree of life. © 2020 Elsevier Ltd
Keywords: enzyme evolution; iridoids; Lamiaceae; nepetalactone; plant metabolites
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