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The invasive land flatworm Arthurdendyus triangulatus has repeated sequences in the mitogenome, extra-long cox2 gene and paralogous nuclear rRNA clusters
No full textInternational audienceUsing a combination of short- and long-reads sequencing, we were able to sequence the complete mitochondrial genome of the invasive ‘New Zealand flatworm’ Arthurdendyus triangulatus (Geoplanidae, Rhynchodeminae, Caenoplanini) and its two complete paralogous nuclear rRNA gene clusters. The mitogenome has a total length of 20,309 bp and contains repetitions that includes two types of tandem-repeats that could not be solved by short-reads sequencing. We also sequenced for the first time the mitogenomes of four species of Caenoplana (Caenoplanini). A maximum likelihood phylogeny associated A. triangulatus with the other Caenoplanini but Parakontikia ventrolineata and Australopacifica atrata were rejected from the Caenoplanini and associated instead with the Rhynchodemini, with Platydemus manokwari. It was found that the mitogenomes of all species of the subfamily Rhynchodeminae share several unusual structural features, including a very long cox2 gene. This is the first time that the complete paralogous rRNA clusters, which differ in length, sequence and seemingly number of copies, were obtained for a Geoplanidae
The relevance of foresight exercises for wine territories facing global polycrisis
No full textInternational audienceWhy is it relevant for actors in a territory in crisis to carry out a foresight exercise? The actors in a territory in crisis (economic crisis, climate crisis, etc.) are collectively facing a decrease in resources and performance. Among these actors, the gap between the realities and the perception of these realities becomes more pronounced, resulting in a loss of meaning and even identity. Opportunistic strategies multiply to the detriment of the common interest. Through a participatory process, the foresight exercise is likely to bring out different contributions within the territory in crisis: the reconstruction of common shared representations, the disarmament of short-term conflicts, the exit from the dictatorship of urgency, the creation of collective strategies to proactively bring about a common future that is most favorable for all
Intercropping Chickpea with Durum Wheat Enhances Nutrient Uptake and Grain Yield Under Low Phosphorus Availability
No full textInternational audienceIntercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production. However, the effect of intercropping legume-cereal in enhancing nutrient uptake and use efficiency under low phosphorus (P) soils is poorly understood. Growth, nodulation, P uptake and use efficiency, and changes in inorganic P availability in the rhizosphere of intercropped species were thus investigated in a field experiment with durum wheat and chickpea either grown alone or intercropped. The results showed that both plant biomass and grain yield, and consequently, the amount of P uptake by intercropped durum wheat increased significantly (30%, 12%, and 46%, respectively) compared with sole cropping during the two seasons. P availability increased in the rhizosphere of the two species, either grown as sole crops or as intercrops, and was enhanced by intercropping. Moreover, total biomass, grain yield, and P uptake were significantly improved, as indicated by higher land equivalent ratio (LER > 1) in intercropping over sole cropping treatments. The increased biomass and grain yield for intercropped durum wheat were associated with the stimulation of P absorption and use efficiency. Furthermore, intercropped wheat was more competitive than their respective chickpea over two growing seasons. The results of this study suggest that changes in the intercropped chickpea rhizosphere may enhance plant growth, P uptake, and use efficiency of the intercropped wheat under low-P soils
Microbial resistance and resilience to drought and rewetting modulate soil N2O emissions with different fertilizers
No full textInternational audienceFuture climate models indicate an enhanced severity of regional drought and frequent rewetting events, which may cause cascading impacts on soil nitrogen cycle and nitrous oxide (N2O) emissions, but the underlying microbial mechanism remains largely unknown. Here we report an incubation study that examined the impacts of soil moisture status and nitrification inhibitor (DCD) on the N2O-producers and N2O-reducers following the application of urea and composted swine manure in an acid soil. The soil moisture treatments included 100 % water-holding capacity (WHC) (wetting, 35.3 % gravimetric soil water content), 40 % WHC (drought, 7 % gravimetric soil water content), and 40 % to 100 % WHC (rewetting). The results showed that N2O emissions were significantly decreased under drought conditions and were significantly increased after rewetting. The resistance of ammonia-oxidizing bacteria and nosZII, which was inhibited by urea or manure application, modulated N2O emissions under drought conditions. The resilience of the functional guilds modulated their dominant role in N2O emissions with rewetting. Ammonia-oxidizing bacteria, nirS-type denitrifying bacteria and nosZI showed significant resilience in response to rewetting. Significant negative relationships were observed between N2O emissions and nosZII clade under wetting condition and between N2O emissions and nosZI clade after rewetting. Our results highlighted the importance of microbial resistance and resilience in modulating N2O emissions, which help to better understand the dominant way of N2O emissions, and consequently make efficient mitigation strategies under the global climate change
Virome release of an invasive exotic plant species in southern France
No full textInternational audienceThe increase in human-mediated introduction of plant species to new regions has resulted in a rise of invasive exotic plant species (IEPS) that has had significant effects on biodiversity and ecosystem processes. One commonly accepted mechanism of invasions is that proposed by the enemy release hypothesis (ERH), which states that IEPS free from their native herbivores and natural enemies in new environments can outcompete indigenous species and become invasive. We here propose the virome release hypothesis (VRH) as a virus-centered variant of the conventional ERH that is only focused on enemies. The VRH predicts that vertically transmitted plant-associated viruses (PAV, encompassing phytoviruses and mycoviruses) should be co-introduced during the dissemination of the IEPS, while horizontally transmitted PAV of IEPS should be left behind or should not be locally transmitted in the introduced area due to a maladaptation of local vectors. To document the VRH, virome richness and composition as well as PAV prevalence, co-infection, host range, and transmission modes were compared between indigenous plant species and an invasive grass, cane bluestem (Bothriochloa barbinodis), in both its introduced range (southern France) and one area of its native range (Sonoran Desert, Arizona, USA). Contrary to the VRH, we show that invasive populations of B. barbinodis in France were not associated with a lower PAV prevalence or richness than native populations of B. barbinodis from the USA. However, comparison of virome compositions and network analyses further revealed more diverse and complex plant-virus interactions in the French ecosystem, with a significant richness of mycoviruses. Setting mycoviruses apart, only one putatively vertically transmitted phytovirus (belonging to the Amalgaviridae family) and one putatively horizontally transmitted phytovirus (belonging to the Geminiviridae family) were identified from B. barbinodis plants in the introduced area. Collectively, these characteristics of the B. barbinodis-associated PAV community in southern France suggest that a virome release phase may have immediately followed the introduction of B. barbinodis to France in the 1960s or 1970s, and that, since then, the invasive populations of this IEPS have already transitioned out of this virome release phase, and have started interacting with several local mycoviruses and a few local plant viruses
Direct pseudomorphic transformation of silica from rice husk into organo-functionalized MCM-41
No full textInternational audienceTo reduce the cost of silica-based materials, an agricultural waste, rice husk (RH), was transformed into higher valuable products such as MCM-41 and organo-functionalized MCM-41 in the frame of circular economy. RH is the biomass waste containing the highest amount of silica (214 g kg−1). Direct calcination of RH led to silica with low surface area (10 m2 g−1), which could not be transformed into MCM-41. After optimization, silica of 310 m2 g−1 was produced by washing RH with HCl 0.1 mol L−1 at 25 °C and calcination at 600 °C. Such silica was successfully transformed in one-step synthesis at 115 °C for 24 h into highly ordered MCM-41 (800 m2 g−1) and organo-functionalized MCM-41 (510–720 m2 g−1) including aminopropyl and amide derivatives of amino acids (leucine, serine and tyrosine). The corresponding organo-triethoxysilanes alone or in mixture were directly added in the synthesis with silica from RH, octadecyltrimethylammonium and NaOH solution. Surfactant removal was successfully performed with EtOH/NH4NO3 solution at 60 °C. The mesopore diameter of the materials were homogeneous and varied from 3.8 to 4.2 nm depending on the organic functions. Thanks to the use of the concept of pseudomorphic transformation, the particle size of the materials ranged from 1 to 100 μm. As proof of concept, the 50–100 μm fraction (30% of the volume) was successfully used to fill columns to run size exclusion chromatography for protein separation. The largest protein, bovine serum albumine (BSA) was excluded from all materials as its kinetic diameter (d = 7.2 nm) was larger than the mesopore diameter. The smallest proteins: carbonic anhydrase (d = 4.2 nm), myoglobin (d = 3.8 nm) and lysozyme (d = 3.4 nm) were retained by the materials. Their retention factor increased as the kinetic diameter decreased, as the mesopore diameter decreased and as the hydrophobicity of the materials increased. The best separation of proteins was obtained with MCM-41 functionalized with both leucine and serine amide derivatives
Estimation of the basic density of Eucalyptus grandis wood chips at different moisture levels using benchtop and handheld NIR instruments
No full textInternational audienceWith the increasing demand for productivity and quality in the forestry sector, near-infrared (NIR) spectroscopy is promising in the monitoring of wood properties, such as density. However, most predictive models are based on spectra acquired in wood at equilibrium moisture content using benchtop equipment. The objective of this study was to evaluate the performance of the NIR instruments in predicting the basic density of Eucalyptus grandis wood at different moisture contents. The wood chips were evaluated from saturated conditions (freshly felled) to hygroscopic equilibrium conditions using benchtop and portable NIR instruments. Principal component analysis (PCA) was performed to verify the behavior of spectral data, partial least squares discriminant analysis (PLS-DA) to classify density categories, and partial least squares regression (PLS-R) to develop predictive models. The moisture gradient was not the limiting factor for the statistical modeling. PCA discriminated 99.50% of the variation in the data, while the PLS-DA correctly categorized in the range of 0-94% the density classes. The models developed by PLS-R with the benchtop instrument showed a prediction coefficient (R2) ranging from 0.79 to 0.85 and those with the portable instrument ranged from 0.77 to 0.82; the ratios of prediction deviation (RPD) were 2.20 and 2.45, respectively. Thus, NIR spectroscopy has shown potential application in wood under saturated conditions, regardless of the type of instrument. In the industrial context, the use of a portable NIR instrument could streamline wood characterization without the need for drying and transporting samples to the laboratories
Coprodscope, un outil de bilan-conseil en gestion des co-produits végétaux et animaux à l’échelle de l’exploitation en zone subhumide du Burkina Faso
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Environments, terrestrial ecosystems and mammalian species: An overview of Southeast Asia in the Late Pleistocene
No full textInternational audienceDuring the highly dynamic, climate-driven Pleistocene period, mammalian communities from the Indomalayan region faced major environmental changes. In the late Middle to the Late Pleistocene, the Sunda Shelf surface was particularly affected under the influence of multiple parameters—tectonic, eustatic and climatic—leading to alternating phases of exposure and flooding. The fossil faunas from the Padang Highlands in Sumatra discovered by Eugène Dubois illustrate episodes of species dispersal during the periods of exposure of land areas. Here, we analyse the assemblages of Sibrambang and Lida Ajer in the light of a selection of mammalian faunas located in continental and insular regions during two possible periods of dispersion, c. 130 ka at the Marine Isotope Stage(MIS) 6–5 transition and c. 71 ka at the beginning of MIS 4. We investigated (1) the taxonomic composition of herbivore communities in terms of archaic versus modern taxa; (2) the functions of ecosystems, based on the type of digestive physiology of herbivores (ruminant versus non-ruminant) per body mass category; and (3) the relative abundance of some Artiodactyla, Perissodactyla and Primates. Our results show that, at the time of the earliest range expansion of modern species into Sundaland c. 130 ka, diverse functional herbivore communities containing local archaic taxa coexisted in Southeast Asia. Overall, Sundaland seems to have always been less rich in large-bodied herbivore diversity compared to the Indochinese subregion, most probably reflecting the lower heterogeneity of Sundaic ecosystems, even during the period of large connections between land masses. By comparing Duoi U’Oi, Vietnam (Homo sp.; 70–60 ka) and Lida Ajer, Sumatra (Homo sapiens; 73–63 ka), two sites located at different latitudes, the results underscore the different availability to humans of herbivore prey species depending on their relative abundance in highly forested habitats
Dynamics of soil organic carbon pools following conversion of savannah to cocoa agroforestry systems in the Centre region of Cameroon
No full textAfforestation of gramineous-woody savannah with cocoa agroforestry systems (cAFS) is a common farmer practice in Cameroon considered as sustainable. Nevertheless, the effects of afforestation of savannah with cAFS on soil organic carbon (SOC) turnover and content, and the factors controlling SOC accumulation and stabilization are unknown. SOC content at 0-10 cm soil layer, and SOC distribution in soil particle size fractions (0-20 Mu m fraction considered as mineral-associated organic carbon, MAOC; 50-2000 Mu m considered as particulate organic carbon, POC; and 20-50 Mu m), were compared in different systems settled on degraded savannah (orthic ferralsols). These systems included annual cropland (average 5 years old), cocoa monoculture (average 10 years old), and cAFS (from 20 to 60 years old) including different shade tree species such as Albizia adianthifolia, Canarium schweinfurthii, Dacryodes edulis, Milicia excelsa and Ceiba pentandra. Savannah and nearby secondary forest patches were also included in the design as controls. Soil 13C was analysed to investigate the soil carbon turnover after afforestation (C3 plants) of gramineous savannah (C4 plants). SOC significantly increased in the 0-10 cm depth from 10.6 ± 3.1 g C kg-1 in degraded savannah to 17.9 ± 5.6 g C kg-1 in cAFS reaching similar levels as in nearby secondary forests (16.3 ± 5.8 g C kg-1), while annual cropland and cocoa monoculture presented a non-significant decrease in SOC content. These changes were due to rapid loss of SOC derived from savannah plants (C4) - about 76% within the first 15 years after conversion, and higher gain of SOC derived from C3 plants in cAFS than in the other land uses (e.g. from 3.4 ± 1.5 g C kg-1 in savannah to 17.8 ± 5.7 g C kg-1 in cAFS). This SOC enrichment in cAFS was distributed in POC (64%), MAOC (30%) and the intermediate 20-50 Mu m soil fraction (6%). The higher annual litter input accumulated on a longer period in cAFS (20 to 60 years) than in cocoa monoculture (10 years) concomitant with the lower litter recalcitrance of associated trees compared to cocoa could explain the higher enrichment of SOC in all fractions in cAFS. The soil pH and exch. Ca2+ differed under the different shade tree species, and were positively correlated to SOC content. The highest contents of soil exch. Ca2+ induced by Ceiba and Milicia in the top 10 cm soil layer could contribute to increase SOC enrichment under those species through soil aggregation and related C stabilization. We found no strong evidence of the effect of soil texture on additional soil carbon accumulation in cAFS, especially for the more stable C pool (MAOC). Our results evidenced that savannah afforestation with cAFS appears as a valuable option for top soil carbon enrichment and should consider tree species associated to cocoa to enhance soil C sequestration, soil quality and cocoa production sustainability