Global analysis of Coffea canephora Pierre ex Froehner (Rubiaceae) from the Guineo-Congolese region reveals impacts from climatic refuges and migration effects     

Philippe Cubry  Fabien De Bellis  David Pot  Pascal Musoli  Thierry Leroy 《Genetic Resources and Crop Evolution》2013,60(2):483-501

As the second species used for commercial coffee, evaluation of Coffea canephora Pierre ex Froehner population genetics is a challenging task for coffee breeding. This study examined the pattern of genetic variability and genetic relationships of cultivated and wild populations of C. canephora sampled across the Guineo-Congolese region of Africa and some improved populations maintained in field genebanks. A total of 293 individuals, sampled from 17 populations, were genotyped with 39 nuclear microsatellite markers. Genetic diversity and structure were investigated with both a model-based and a graphical approach; isolation by distance was also tested. Relationships between the diversity clusters are discussed with regard to differentiation due to several glacial refuges during the Last Glacial Maximum (LGM). High genetic diversity within C. canephora is confirmed with a mean number of alleles of 11.85 per marker, a mean gene diversity of 0.72 and a mean observed heterozygosity of 0.36. An overall structure of two main groups (Guinean and Congolese) subdivided in six subgroups (2 for the Guinean and 4 for the Congolese) was found, including one described for the first time in the Guinean group. A fine structure within the Guinean group was also newly detected. Genetic structure of C. canephora appears to be consistent with its geographic repartition at the continent scale. Structure of diversity was found in accordance with localizations of refuge zones during LGM and migration from this period. Results from this genetic structure study raise our capabilities to better manage and use the collections of genetics resources for breeding purposes. Those results will be used in future association studies to optimize the number of genotypes to be phenotyped.  相似文献   

Comparison of Genetic and Virulence Diversity of Melampsora larici-populina Populations on Wild and Cultivated Poplar and Influence of the Alternate Host     

Gérard PR  Husson C  Pinon J  Frey P 《Phytopathology》2006,96(9):1027-1036

ABSTRACT The aims of this study were, first, to compare the genetic and virulence diversity between populations of the rust fungus Melampsora larici-populina on wild and cultivated poplar stands and, second, to investigate the influence of the presence of the alternate host of the pathogen, larch, on which its sexual reproduction occurs, on these diversities. Nine French M. larici-populina populations collected from poplar trees in autumn and four populations collected from larch trees during the following spring were analyzed using both virulence factors and neutral markers. In all, 30 pathotypes were identified within the 13 populations studied. The pathotypic structure clearly distinguished the cultivated stands with high richness and complexity from the wild stands with low richness and complexity. High linkage disequilibria between virulences indicated preferential virulence associations, probably due to selection by the host. In all, 19 random amplified polymorphic DNA (RAPD) markers were used, which revealed a very high genetic diversity in the 743 isolates analyzed. The nine populations from poplar appeared moderately differentiated, indicating long-distance gene flow, and no isolation by distance was found. Linkage disequilibria between RAPD markers generally were low, indicating frequent recombination, but they were not lower in populations located near larch, probably due to long-distance dispersal.  相似文献   

Nitrous oxide emission from herbicide-treated soybean   总被引：5，自引：0，他引：5  

Zhang Lifeng  Pascal Boeckx  C. Guanxiong  Oswald Van Cleemput 《Biology and Fertility of Soils》2000,32(2):173-176

 The emission of N₂O from soybean plants treated with the herbicides dichlorophenoxyacetic acid (2,4-D) and bromoxynil was studied. The N₂O flux from 2,4-D- and bromoxynil-treated soybean was 14.1 ng N₂O-N g^–1 fresh weight h^–1 and 19.7 ng N₂O-N g^–1 fresh weight h^–1, respectively, i.e. approximately twice that of the controls. The NO₂ ^–-N concentration in 2,4-D- and in bromoxynil-treated soybean was about 8 μg N g^–1 fresh weight, i.e. fivefold the concentration found in control plants. The NO₃ ^– content in herbicide-treated soybean did not differ significantly from that of the control plants. Consequently, the accumulation of NO₂ ^–-N during the assimilation of NO₃ ^–-N was thought to cause the observed N₂O release. Probably, N₂O is a by-product produced during either the reaction of NO₂ ^–-N with plant metabolites or NO₂ ^–-N decomposition. Final conclusions must await further experiments. Received: 5 November 1999  相似文献   

Feeding requirements of sea bream (Sparus aurata) larvae under intensive rearing conditions: Development of a fuzzy logic controller for feeding     

Nikos Papandroulakis  George Markakis  Pascal Divanach  Maroudio Kentouri 《Aquacultural Engineering》2000,21(4):285-299

Applied methods for larval rearing suffer from the difficulty of accurately predicting larvae quantitative feeding requirements for optimum growth. Even when known, requirements change according to the behavior of each population reared. Computer based feeding systems require tools for adapting the delivered amounts of food to the needs of the reared population. In this work the daily feeding requirements of sea bream (Sparus aurata) larvae were estimated, and based on these estimations a fuzzy logic controller (FLC) for feeding was designed and developed. Sea bream larvae were reared, in triplicate, under intensive conditions in a pilot scale rearing system for 20 days with the pseudo-green water method. Larvae reached 6.7±0.6 mm (mean value and S.D.) at the end of the experimental period while the mean survival of the populations was 48.0±12.6%. Consumption was 0.017±0.009 mg of carbon per individual at first feeding and increased to 0.198±0.032 mg at day 20 post-hatching. The findings were used for the development of a FLC for feeding that adapts the amount of food delivered to the larvae according to changes in the reared population. The FLC utilizes five linguistic variables describing the state of the population and a rule base composed of 316 rules. The developed FLC allows the use of computer based feeding systems during rearing of early larval stages.  相似文献   

Exposure to Temperature and Insecticides Modulates the Expression of Small Noncoding RNA-Associated Transcripts in the Colorado Potato Beetle,Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)     

Mariem Ben Youssef  Brigitte Christelle Oudraogo  Pierre Bastarache  Pascal Dumas  Chandra E Moffat  Jessica L Vickruck  Pier Jr Morin 《Journal of insect science (Online)》2022,22(1)

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The permeation barrier of plant cuticles: uptake of active ingredients is limited by very long‐chain aliphatic rather than cyclic wax compounds     

Simona Staiger  Pascal Seufert  Katja Arand  Markus Burghardt  Christian Popp  Markus Riederer 《Pest management science》2019,75(12):3405-3412

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Induction of Defense Gene Expression and the Resistance of Date Palm to Fusarium oxysporum f. sp. Albedinis in Response to Alginate Extracted from Bifurcaria bifurcata     

Soukaina Bouissil  Claire Gurin  Jane Roche  Pascal Dubessay  Zainab El Alaoui-Talibi  Guillaume Pierre  Philippe Michaud  Said Mouzeyar  Cdric Delattre  Cherkaoui El Modafar 《Marine drugs》2022,20(2)

In many African countries, the Bayoud is a common disease spread involving the fungus Fusarium oxusporum f. sp. albedinis (Foa). The induction of plant natural defenses through the use of seaweed polysaccharides to help plants against pathogens is currently a biological and ecological approach that is gaining more and more importance. In the present study, we used alginate, a natural polysaccharide extracted from a brown algae Bifurcaria bifurcata, to activate date palm defenses, which involve phenylalanine ammonia-lyase (PAL), a key enzyme of phenylpropanoid metabolism. The results obtained showed that at low concentration (1 g·L⁻¹), alginate stimulated PAL activity in date palm roots 5 times more compared to the negative control (water-treated) after 24 h following treatment and 2.5 times more compared to the laminarin used as a positive stimulator of plant natural defenses (positive control of induction). Using qRT-PCR, the expression of a selection of genes involved in three different levels of defense mechanisms known to be involved in response to biotic stresses were investigated. The results showed that, generally, the PAL gene tested and the genes encoding enzymes involved in early oxidative events (SOD and LOX) were overexpressed in the alginate-treated plants compared to their levels in the positive and negative controls. POD and PR protein genes selected encoding β-(1,3)-glucanases and chitinases in this study did not show any significant difference between treatments; suggesting that other genes encoding POD and PR proteins that were not selected may be involved. After 17 weeks following the inoculation of the plants with the pathogen Foa, treatment with alginate reduced the mortality rate by up to 80% compared to the rate in control plants (non-elicited) and plants pretreated with laminarin, which agrees with the induction of defense gene expression and the stimulation of natural defenses in date palm with alginate after 24 h. These results open promising prospects for the use of alginate in agriculture as an inducer that triggers immunity of plants against telluric pathogens in general and of date palm against Fusarium oxysporum f. sp. albedinis in particular.  相似文献   

Integrating local knowledge into soil science to improve soil fertility     

Sougueh Cheik  Pascal Jouquet 《Soil Use and Management》2020,36(4):561-564

Environmental changes are threatening current and future food security. In this context, it is imperative to design agricultural systems that are resilient to increasing frequent climate shocks, losses in biodiversity and soil fertility and to increasing demand from our societies because of population growth and consumption patterns. The emergence of sustainability science reminds us that soil management cannot be successfully approached by the independent actions of individual categories of actors, namely soil researchers or agronomists. Therefore, we advocate for more holistic and transdisciplinary research that takes into account the social, cultural, environmental and economic impacts of agricultural practices. Using examples of agricultural practices that aim to use the activity of termites to improve the services delivered by ecosystems (e.g. the Zai system), rather than considering them pests and trying to eradicate them from lands, we discuss the interest of traditional agricultural practices as sources of inspiration for soil scientists and for the identification of tomorrow's agricultural practices.  相似文献   

Using otolith microchemistry to reconstruct habitat use of American eels Anguilla rostrata in the St. Lawrence River–Lake Ontario system          下载免费PDF全文

José Benchetrit  Mélanie Béguer‐Pon  Pascal Sirois  Martin Castonguay  John Fitzsimons  Julian J. Dodson 《Ecology of Freshwater Fish》2017,26(1):19-33

Catadromy among freshwater eels is increasingly recognised as being facultative, with some individuals carrying out growth exclusively in brackish or coastal marine waters, or switching between brackish or marine waters and freshwater habitats. In an attempt to reconstruct habitat use of yellow‐stage American eels in a large river‐lake ecosystem, trace element line scans were obtained, using LA‐ICP‐MS, from the otoliths of 110 eels sampled at various locations throughout the St. Lawrence River–Lake Ontario (SLRLO) system. Elemental profiles for strontium (Sr), barium (Ba), manganese (Mn) and magnesium (Mg) enabled us to distinguish three chemical signatures that appear to represent three distinct habitats within the SLRLO. Of these, one was shown to likely correspond to the brackish estuary (high strontium values). The other two signatures, characterised by low strontium but variable concentrations of barium and manganese, may correspond to habitats within the main‐stem St. Lawrence River and one or more of its tributaries. Most (78%) of the switches among habitats occurred within the first four years after recruitment suggesting an increasing likelihood for eels to maintain residence in one habitat as they grow older. This suggests that tributaries may provide important habitats for American eels during the first several years after recruiting to the SLRLO. In addition, our results suggest that a small proportion American eels in the SLRLO can undertake movements on the order of at least 200 km during the early growth stage. This information has important implications for the management and conservation of this species in the system.  相似文献   

Determination of poly‐β‐hydroxybutyrate assimilation by postlarval whiteleg shrimp,Litopenaeus vannamei using stable 13C isotope tracing     

Gladys Ludevese‐Pascual  Farhana Ahmed  Marleen De Troch  Edgar Amar  Joseph Leopoldo Laranja  Samuel Bode  Pascal Boeckx  Peter Bossier  Peter De Schryver 《Journal of the World Aquaculture Society》2021,52(1):184-194

A preliminary study was conducted to demonstrate fate of the bacterial storage compound poly‐β‐hydroxybutyrate (PHB) once ingested and degraded in vivo in crustaceans. The 2% supplementation of ¹³C‐labeled Ralstonia eutropha DSM545 containing 75% PHB on dry weight in postlarval whiteleg shrimp, Litopenaeus vannamei resulted in consistent enrichment of two fatty acids (containing 14–24 carbons [C] in length ) pentadecanoic acid (15:0) and palmitic acid (16:0) in all lipid fractions. This could indicate that ¹³C signal may not only originate from the PHB but partly from the structural components of the bacterial cell. There was a trend of lower ¹³C enrichment in various lipid fractions of the postlarvae as compared to the diet. These findings may have important implications as to potential of PHB as energy source rather than as building block. There was a rapid transfer of ¹³C in the postlarvae as seen by the significant ¹³C enrichment in the tissues 4 hr after feeding with labeled bacterial cells. Overall, the assimilation of PHB in crustacean tissues is demonstrated for the first time. Our results indicate that PHB once ingested is rapidly assimilated in the tissues and could probably act as an energy source rather than as a building block.  相似文献