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1.
Glob Chang Biol ; 30(4): e17282, 2024 Apr.
Article de Anglais | MEDLINE | ID: mdl-38619685

RÉSUMÉ

Given the current environmental crisis, biodiversity protection is one of the most urgent socio-environmental priorities. However, the effectiveness of protected areas (PAs), the primary strategy for safeguarding ecosystems, is challenged by global climate change (GCC), with evidence showing that species are shifting their distributions into new areas, causing novel species assemblages. Therefore, there is a need to evaluate PAs' present and future effectiveness for biodiversity under the GCC. Here, we analyzed changes in the spatiotemporal patterns of taxonomic and phylogenetic diversity (PD) of plants associated with the Neotropical seasonally dry forest (NSDF) under GCC scenarios. We modeled the climatic niche of over 1000 plant species in five representative families (in terms of abundance, dominance, and endemism) of the NSDF. We predicted their potential distributions in the present and future years (2040, 2060, and 2080) based on an intermediate scenario of shared socio-economic pathways (SSP 3.70), allowing species to disperse to new sites or constrained to the current distribution. Then, we tested if the current PAs network represents the taxonomic and phylogenetic diversities. Our results suggest that GCC could promote novel species assemblages with local responses (communities' modifications) across the biome. In general, models predicted losses in the taxonomic and phylogenetic diversities of all the five plant families analyzed across the distribution of the NSDF. However, in the northern floristic groups (i.e., Antilles and Mesoamerica) of the NSDF, taxonomic and PD will be stable in GCC projections. In contrast, across the NSDF in South America, some cores will lose diversity while others will gain diversity under GCC scenarios. PAs in some NSDF regions appeared insufficient to protect the NSDF diversity. Thus, there is an urgent need to assess how the PA system could be better reconfigured to warrant the protection of the NSDF.


Dada la actual crisis ambiental, la protección de la biodiversidad se presenta como una de las prioridades socio ambientales más urgentes. Sin embargo, la efectividad de las áreas protegidas (AP), la estrategia principal para salvaguardar los ecosistemas, se ve desafiada por el cambio climático global (CCG), con evidencia que muestra que las especies están desplazando sus distribuciones hacia nuevas áreas, provocando conjuntos de especies novedosos. Por lo tanto, es necesario evaluar la efectividad actual y futura de las AP para la biodiversidad bajo el CCG. En este contexto, analizamos cambios en los patrones espacio­temporales de diversidad taxonómica y filogenética de plantas asociadas al bosque estacionalmente seco neotropical (BES) bajo escenarios de CCG. Modelamos el nicho climático de más de 1,000 especies de plantas en cinco familias representativas (en términos de abundancia, dominancia y endemismo) del BES. Pronosticamos sus distribuciones potenciales en los años actuales y futuros (2040, 2060 y 2080) basándonos en un escenario intermedio de trayectorias socioeconómicas compartidas (SSP 3.70), permitiendo que las especies se dispersen a nuevos sitios o estén limitadas a la distribución actual. Luego, evaluamos si la red actual de AP representa las diversidades taxonómicas y filogenéticas. Nuestros resultados sugieren que el CCG podría promover conjuntos de especies novedosos con respuestas locales (modificaciones en las comunidades) en todo el bioma. En general, los modelos pronosticaron pérdidas en las diversidades taxonómicas y filogenéticas de las cinco familias de plantas analizadas en la distribución del BES. Sin embargo, en los grupos florísticos del norte (es decir, Antillas y Mesoamérica) del BSDN, la diversidad taxonómica y filogenética se mantendrá estable en las proyecciones de CCG. En cambio, en toda la región del BES en América del Sur, algunos núcleos perderán diversidad mientras que otros ganarán diversidad bajo escenarios de CCG. Algunas AP en regiones del BES parecen ser insuficientes para proteger la diversidad del bioma. Por lo tanto, es urgente evaluar cómo se podría reconfigurar mejor el sistema de AP para garantizar la protección del BES.


Sujet(s)
Écosystème , Forêts , Phylogenèse , Biodiversité , Changement climatique
2.
Yeast ; 41(1-2): 52-63, 2024 Jan.
Article de Anglais | MEDLINE | ID: mdl-38146767

RÉSUMÉ

In this study, we describe Nakazawaea atacamensis f. a., sp. nov., a novel species obtained from Neltuma chilensis plant samples in Chile's hyperarid Atacama Desert. In total, three strains of N. atacamensis were obtained from independent N. chilensis samples (synonym Prosopis chilensis, Algarrobo). Two strains were obtained from bark samples, while the third strain was obtained from bark-exuded gum from another tree. The novel species was defined using molecular characteristics and subsequently characterized with respect to morphological, physiological, and biochemical properties. A neighbor-joining analysis using the sequences of the D1/D2 domains of the large subunit ribosomal RNA gene revealed that N. atacamensis clustered with Nakazawaea pomicola. The sequence of N. atacamensis differed from closely related species by 1.3%-5.2% in the D1/D2 domains. A phylogenomic analysis based on single-nucleotide polymorphism's data confirms that the novel species belongs to the genus Nakazawaea, where N. atacamensis clustered with N. peltata. Phenotypic comparisons demonstrated that N. atacamensis exhibited distinct carbon assimilation patterns compared to its related species. Genome sequencing of the strain ATA-11A-BT revealed a genome size of approximately 12.4 Mbp, similar to other Nakazawaea species, with 5116 protein-coding genes annotated using InterProScan. In addition, N. atacamensis exhibited the capacity to ferment synthetic wine must, representing a potential new yeast for mono or co-culture wine fermentations. This comprehensive study expands our understanding of the genus Nakazawaea and highlights the ecological and industrial potential of N. atacamensis in fermentation processes. The holotype of N. atacamensis sp. nov. is CBS 18375T . The Mycobank number is MB 849680.


Sujet(s)
Saccharomycetales , Vin , Fermentation , Phylogenèse , Saccharomycetales/génétique , Pichia/génétique , Séquence nucléotidique , Analyse de séquence d'ADN , ADN fongique/génétique , Espaceur de l'ADN ribosomique/génétique
3.
Int J Syst Evol Microbiol ; 73(10)2023 Oct.
Article de Anglais | MEDLINE | ID: mdl-37861393

RÉSUMÉ

A Gram-stain-positive, catalase-positive, non-motile bacteria, with a rod-coccus cycle (designated as EH-1B-1T) was isolated from a soil sample from Union Glacier in Ellsworth Mountains, Antarctica. Strain EH-1B-1T had an optimal growth temperature of 28 °C and grew at pH 7-10. The major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, C16 : 0 and anteiso-C17 : 0. The G+C content based on the whole genome sequence was 63.1 mol%. Strain EH-1B-1T was most closely related to members of the genus Arthrobacter, namely Arthrobacter subterraneus and Arthrobacter tumbae. The strain grew on tryptic soy agar, Reasoner's 2A agar, lysogeny broth agar and nutrient agar. The average nucleotide identity and digital DNA-DNA hybridization values between strain EH-1B-1T and its closest reference type strains ranged from 78 to 88 % and from 20.9 to 36.3 %, respectively. Based on phenotypic, chemotypic and genotypic evidence, it is proposed that strain EH-1B-1T represents a novel species of Arthrobacter, for which the name Arthrobacter vasquezii sp. nov. is proposed, with strain EH-1B-1T (RGM 3386T=LMG 32961T) as the type strain.


Sujet(s)
Arthrobacter , Acides gras , Acides gras/composition chimique , Phospholipides/composition chimique , Couche de glace , Régions antarctiques , Agar-agar , Composition en bases nucléiques , Phylogenèse , ADN bactérien/génétique , ARN ribosomique 16S/génétique , Techniques de typage bactérien , Analyse de séquence d'ADN , Microbiologie du sol , Vitamine K2/composition chimique , Peptidoglycane/composition chimique , Sol
4.
Syst Appl Microbiol ; 46(3): 126415, 2023 May.
Article de Anglais | MEDLINE | ID: mdl-36933352

RÉSUMÉ

Two putative novel Burkholderia cenocepacia lineages found in the semi-arid region of north-east Brazil causing onion sour skin were studied using genomic approaches to determine their taxonomic position. Four strains belonging to one novel lineage (CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171) and one strain (CCRMBC51) belonging to another novel lineage had their whole genome sequenced to carry out taxogenomic analyses. The phylogenomic tree built using the type (strain) genome server (TYGS) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 into the same clade, while grouped the strain CCRMBC51 separately. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) analysis showed values above 99.21 % and 93.2 %, respectively, among the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171, while ANI and dDDH values between these strains and the strain CCRMBC51 were below 94.49 % and 56.6 %, respectively. All these strains showed ANI and dDDH values below 94.78 % and 58.8 % concerning type strains of the B. cepacia complex (Bcc) species. The phylogenetic maximum likelihood tree constructed based on the multilocus sequence analysis of core genes (cMLSA) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 and the strain CCRMBC51 in two exclusive clades, which did not cluster with any known species of the Bcc. Therefore, combined data from TYGS, ANI, dDDH, and cMLSA demonstrated that the strains represent two novel species of the Bcc, which we classified as Burkholderia semiarida sp. nov. and Burkholderia sola sp. nov., and proposed the strains CCRMBC74T (=IBSBF 3371 T = CBAS 905 T) and CCRMBC51T (=IBSBF3370T = CBAS 904 T) as type strains, respectively.


Sujet(s)
Burkholderia , Burkholderia/génétique , Oignons/génétique , Analyse de séquence d'ADN , Phylogenèse , ARN ribosomique 16S/génétique , Hybridation d'acides nucléiques , ADN , ADN bactérien/génétique , Techniques de typage bactérien , Acides gras
5.
Viruses ; 13(11)2021 10 26.
Article de Anglais | MEDLINE | ID: mdl-34834961

RÉSUMÉ

Nested PCRs with circovirus/cyclovirus pan-rep (replicase gene) primers detected eukaryotic circular Rep-encoding single-stranded DNA (CRESS DNA) viruses in three (samples CN9E, CN16E and CN34) of 18 canine parvovirus-2-positive fecal samples from household dogs with hemorrhagic gastroenteritis on the Caribbean island of Nevis. The complete genomes of CRESS DNA virus CN9E, CN16E and CN34 were determined by inverse nested PCRs. Based on (i) genome organization, (ii) location of the putative origin of replication, (iii) pairwise genome-wide sequence identities, (iv) the presence of conserved motifs in the putative replication-associated protein (Rep) and the arginine-rich region in the amino terminus of the putative capsid protein (Cp) and (v) a phylogenetic analysis, CN9E, CN16E and CN34 were classified as cycloviruses. Canine-associated cycloviruses CN16E and CN34 were closely related to each other and shared low genome-wide nucleotide (59.642-59.704%), deduced Rep (35.018-35.379%) and Cp (26.601%) amino acid sequence identities with CN9E. All the three canine-associated cycloviruses shared < 80% genome-wide pairwise nucleotide sequence identities with cycloviruses from other animals/environmental samples, constituting two novel species (CN9E and CN16E/34) within the genus Cyclovirus. Considering the feeding habits of dogs, we could not determine whether the cycloviruses were of dietary origin or infected the host. Interestingly, the CN9E putative Rep-encoding open reading frame was found to use the invertebrate mitochondrial genetic code with an alternative initiation codon (ATA) for translation, corroborating the hypothesis that cycloviruses are actually arthropod-infecting viruses. To our knowledge, this is the first report on the detection and complete genome analysis of cycloviruses from domestic dogs.


Sujet(s)
Circoviridae/classification , Circoviridae/isolement et purification , Maladies des chiens/virologie , Gastroentérite/virologie , Phylogenèse , Séquence d'acides aminés , Animaux , Protéines de capside/génétique , Circoviridae/génétique , Virus à ADN/génétique , ADN viral/génétique , Chiens , Fèces/virologie , Génome viral , Séquençage nucléotidique à haut débit , Cadres ouverts de lecture , Parvovirus canin/classification , Parvovirus canin/génétique , Parvovirus canin/isolement et purification , Saint-Christophe-et-Niévès , Analyse de séquence d'ADN , Séquençage du génome entier
6.
Arch Microbiol ; 203(4): 1807-1823, 2021 May.
Article de Anglais | MEDLINE | ID: mdl-33491161

RÉSUMÉ

Heavy-metal (HM) contamination is a huge environmental problem in many countries including Mexico. Currently, microorganisms with multiple heavy-metal resistance and/or plant-promoting characteristics have been widely used for bioremediation of HM-contaminated soils. The aim of the study was isolated bacteria with multiple heavy-metal resistance and to determinate the resistance mechanism developed by these organisms. A total of 138 aerobic bacteria were isolated from soil and sediments surrounding the Lerma-Chapala basin located in the boundary of the States of Michoacán and Jalisco states of Mexico. One hundred and eight strains showed at least 1 plant growth-promoting features. The Lerma-Chapala basin bacteria were also resistant to high concentrations of HMs including the metalloid arsenic. Sequence analysis of 16S RNA genes reveled that these bacteria were mainly affiliated to the phyla Proteobacteria (38%), Firmicutes (31%) and Actinobacteria (25%), covering 21 genera with Bacillus as the most abundant one. Among them, at least 27 putative novel species were detected in the genera Acinetobacter, Arthrobacter, Bacillus, Agrobacterium, Dyadobacter, Enterobacter, Exiguobacterium, Kluyvera, Micrococcus, Microbacterium and Psychrobacter. In addition, these bacteria developed various heavy-metal-resistance mechanisms, such as biosorption/bioaccumulation, immobilization and detoxification. Therefore, the bacteria isolated from soils and sediments of Lerma-Chapala basin could be used in bioremediation strategies.


Sujet(s)
Bactéries/métabolisme , Dépollution biologique de l'environnement , Résistance bactérienne aux médicaments/génétique , Métaux lourds/analyse , Métaux lourds/métabolisme , Arsenic/analyse , Bactéries/génétique , Bactéries/isolement et purification , Mexique , Développement des plantes , Sol/composition chimique , Microbiologie du sol , Polluants du sol/analyse
7.
FEMS Yeast Res ; 20(6)2020 09 01.
Article de Anglais | MEDLINE | ID: mdl-32710773

RÉSUMÉ

In recent years, 'multi-omic' sciences have affected all aspects of fundamental and applied biological research. Yeast taxonomists, though somewhat timidly, have begun to incorporate complete genomic sequences into the description of novel taxa, taking advantage of these powerful data to calculate more reliable genetic distances, construct more robust phylogenies, correlate genotype with phenotype and even reveal cryptic sexual behaviors. However, the use of genomic data in formal yeast species descriptions is far from widespread. The present review examines published examples of genome-based species descriptions of yeasts, highlights relevant bioinformatic approaches, provides recommendations for new users and discusses some of the challenges facing the genome-based systematics of yeasts.


Sujet(s)
Génome fongique , Séquençage du génome entier , Levures/classification , Biologie informatique , Phylogenèse
8.
Int J Syst Evol Microbiol ; 70(5): 3348-3354, 2020 May.
Article de Anglais | MEDLINE | ID: mdl-32375942

RÉSUMÉ

A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic, metal-contaminated stream draining from an abandoned underground coal mine (Trongol mine), situated close to Curanilahue, Biobío Region, Chile. The isolate (USS-CCA1T) was demonstrated to be a heterotroph that catalysed under aerobic conditions the oxidation of ferrous iron and the reduction of ferric iron under anaerobic conditions, but not the oxidation of sulfur nor hydrogen. USS-CCA1T is a Gram-positive, motile, short rod-shaped, mesophilic bacterium with a temperature growth optimum at 30 °C (range 20-39 °C). It was categorized as an extreme acidophile growing between 1.7 and 4.5 and optimally at pH 3.0. The G+C content of the chromosomal DNA of the isolate was 74.1 mol%, which is highly related to Aciditerrimonas ferrireducens IC-180T , (the most closely related genus; 94.4 % 16S rRNA gene identity), and higher than other acidophilic actinobacteria. The isolate (USS-CCA1T) was shown to form a distinct 16S rRNA clade from characterized acidophilic actinobacteria, well separated from the genera Acidimicrobium, Ferrimicrobium, Ferrithrix, 'Acidithrix' and Aciditerrimonas. Genomic indexes (ANIb, DDH, AAI, POCP) derived from the USS-CCA1T draft genome sequence (deposited at DDBJ/ENA/GenBank under the accession WJHE00000000) support assignment of the isolate to a new species and a new genus within the Acidimicrobiaceae family. Isolate USS-CCA1T is the designated type strain of the novel species Acidiferrimicrobium australe (=DSM 106828T,=RGM 2506T).


Sujet(s)
Actinobacteria/classification , Processus hétérotrophes , Fer/métabolisme , Mine , Phylogenèse , Microbiologie de l'eau , Acides , Actinobacteria/isolement et purification , Techniques de typage bactérien , Composition en bases nucléiques , Chili , ADN bactérien/génétique , Acides gras/composition chimique , Concentration en ions d'hydrogène , Oxydoréduction , ARN ribosomique 16S/génétique , Analyse de séquence d'ADN
9.
Arch Microbiol ; 200(9): 1365-1369, 2018 Nov.
Article de Anglais | MEDLINE | ID: mdl-29974159

RÉSUMÉ

A novel Gram-negative, rod-shaped, non-motile bacterium, designated C1BT was isolated from a soil sample of a chrysanthemum plantation in Campinas, Brazil. Strain C1BT formed white colonies on BHI medium, it produces acid from D-lactose, D-mannose, D-arabinose, but does not produce from D-adonitol, m-inositol, D-melibiose, D-raffinose and D-sorbitol and it is negative for lysine and ornithine decarboxylase, phenylalanine deaminase, and citrate. Phylogenetic analysis based on 16S rRNA and rpoB genes sequences showed that strain C1BT has a similarity of 98.2 and 96.8% with different species of Buttiauxella genus. Major fatty acids were C16:0, summed features 4 (C16:1 ω7c and iso-C15:0 2OH), summed features 7 (C18:1 ω7c, C18:1 ω9t, and/or C18:1 ω12t), C17:0 cyclo, summed features 3 (iso-C16:1 I and C14:0 3OH) and C14:0. The mole percent of G+C was 49.6 mol%. Based on these results, a new species Buttiauxella chrysanthemi is proposed. The type strain is C1BT (= CPQBA 1120/15T = CMRVSP5791T).


Sujet(s)
Chrysanthemum/microbiologie , Enterobacteriaceae/classification , Enterobacteriaceae/isolement et purification , Techniques de typage bactérien , Composition en bases nucléiques , Brésil , ADN bactérien/génétique , DNA-directed RNA polymerases/génétique , Enterobacteriaceae/génétique , Enterobacteriaceae/métabolisme , Acides gras/analyse , Hybridation d'acides nucléiques , Phospholipides/analyse , Phylogenèse , ARN ribosomique 16S/génétique , Analyse de séquence d'ADN , Microbiologie du sol
10.
Antonie Van Leeuwenhoek ; 111(10): 1845-1853, 2018 Oct.
Article de Anglais | MEDLINE | ID: mdl-29603043

RÉSUMÉ

A Gram-stain negative, aerobic, rod-shaped, non-motile, yellow-pigmented and non-spore-forming bacterial strain, designated PM5-8T, was isolated from a culture of a marine toxigenic dinoflagellate Prorocentrum mexicanum PM01. Strain PM5-8T grew at 15-35 °C (optimum, 25-30 °C) and pH 6-11 (optimum, 7.5-8). Cells required at least 1.5% (w/v) NaCl for growth, and can tolerate up to 7.0% with the optimum of 4%. Phylogenetic analysis based on 16S rRNA gene sequence revealed that the strain PM5-8T is closely related to members of the genus Hoeflea, with high sequence similarities with Hoeflea halophila JG120-1T (97.06%) and Hoeflea alexandrii AM1V30T (97.01%). DNA-DNA hybridization values between the isolate and other type strains of recognized species of the genus Hoeflea were between 11.8 and 25.2%, which is far below the value of 70% threshold for species delineation. The DNA G + C content was 50.3 mol%. The predominant cellular fatty acids of the strain were identified as summed feature 8 (C16:1 ω7c and/or C16:1 ω6c; 51.5%), C18:1 ω7c 11-methyl (20.7%), C16:0 (17.2%) and C18:0 (5.7%). The major respiratory quinone was Q-10. Polar lipids profiles contained phosphatidylcholine, phosphatidylglycerol, sulfoquinovosyl diacylglycerol, phosphatidylmono- methylethanolamine, phosphatidylethanolamine and four unidentified lipids. On the basis of the polyphasic taxonomic data presented, strain PM5-8T (= CCTCC AB 2016294T = KCTC 62490T) represents a novel species of the genus Hoeflea, for which the name Hoeflea prorocentri sp. nov. is proposed.


Sujet(s)
Organismes aquatiques/microbiologie , Dinoflagellida/microbiologie , Bactéries aérobies à Gram négatif/classification , ADN bactérien , Bactéries aérobies à Gram négatif/composition chimique , Bactéries aérobies à Gram négatif/génétique , Bactéries aérobies à Gram négatif/isolement et purification , Métabolomique/méthodes , Typage moléculaire , Phénotype , Phylogenèse , ARN ribosomique 16S/génétique
11.
Transbound Emerg Dis ; 65(2): 357-362, 2018 Apr.
Article de Anglais | MEDLINE | ID: mdl-29363276

RÉSUMÉ

This study aimed to screen wild rodents from southern Chile, for the presence of Anaplasmatacea. Spleen samples from 33 wild rodents trapped in Valdivia Province were screened by conventional PCR (cPCR), targeting the Anaplasmataceae 16S rRNA gene (16S). Positive samples were further evaluated, targeting a larger 16S fragment, groEL operon, and gltA gene, followed by sequencing and phylogenetic analysis. Anaplasmataceae DNA was detected in 15% (five of 33) of the tested rodents (Abrothrix sp. [four of five] and Mus musculus [one of five]). Analysis of sequenced products based on the 16S gene revealed high similarity with "Ca. Neoehrlichia mikurensis," "Ca. Neoehrlichia lotoris" and "Ca. Neoehrlichia arcana" (97.8%-98.6%). A lower similarity was observed with Candidatus Neoehrlichia groEL (89.7%-92%) and gltA (79.5%-79.9%) loci. According to the 16SrRNA, groEL and gltA phylogenetic analyses, two closely related genotypes of "Candidatus Neoehrlichia" spp. from Chile were observed, which clustered together in a separate clade from other species in this genus. This study suggests the presence of two genotypes of a novel species of "Candidatus Neoehrlichia," proposed as "Candidatus Neoehrlichia chilensis," circulating in rodents from Chile. This is the first report of "Ca. Neoehrlichia" species in rodents from America.


Sujet(s)
Infections à Anaplasmataceae/médecine vétérinaire , Anaplasmataceae/isolement et purification , Animaux sauvages/microbiologie , Rodentia/microbiologie , Anaplasmataceae/génétique , Infections à Anaplasmataceae/diagnostic , Infections à Anaplasmataceae/épidémiologie , Animaux , Séquence nucléotidique , Chili/épidémiologie , ADN bactérien/génétique , Génotype , Souris , Phylogenèse , Réaction de polymérisation en chaîne/médecine vétérinaire , ARN ribosomique 16S/génétique
12.
Zookeys ; (481): 25-38, 2015.
Article de Anglais | MEDLINE | ID: mdl-25685030

RÉSUMÉ

The freshwater genus Hyalella Smith, 1874 has a distribution restricted to the Western Hemisphere with most species being found in South America. In this report we describe a new species of Hyalella from the Atlantic Forest of the Misiones province, Argentina.

13.
Evol Appl ; 5(8): 869-78, 2012 Dec.
Article de Anglais | MEDLINE | ID: mdl-23346231

RÉSUMÉ

Assessing risk from a novel pest or pathogen requires knowing which local plant species are susceptible. Empirical data on the local host range of novel pests are usually lacking, but we know that some pests are more likely to attack closely related plant species than species separated by greater evolutionary distance. We use the Global Pest and Disease Database, an internal database maintained by the United States Department of Agriculture Animal and Plant Health Inspection Service - Plant Protection and Quarantine Division (USDA APHIS-PPQ), to evaluate the strength of the phylogenetic signal in host range for nine major groups of plant pests and pathogens. Eight of nine groups showed significant phylogenetic signal in host range. Additionally, pests and pathogens with more known hosts attacked a phylogenetically broader range of hosts. This suggests that easily obtained data - the number of known hosts and the phylogenetic distance between known hosts and other species of interest - can be used to predict which plant species are likely to be susceptible to a particular pest. This can facilitate rapid assessment of risk from novel pests and pathogens when empirical host range data are not yet available and guide efficient collection of empirical data for risk evaluation.

14.
J Phycol ; 44(5): 1322-34, 2008 Oct.
Article de Anglais | MEDLINE | ID: mdl-27041729

RÉSUMÉ

A cyanobacterial mat colonizing the leaves of Eucalyptus grandis was determined to be responsible for serious damage affecting the growth and development of whole plants under the clonal hybrid nursery conditions. The dominant cyanobacterial species was isolated in BG-11 medium lacking a source of combined nitrogen and identified by cell morphology characters and molecular phylogenetic analysis (16S rRNA gene and cpcBA-IGS sequences). The isolated strain represents a novel species of the genus Brasilonema and is designated Brasilonema octagenarum strain UFV-E1. Thin sections of E. grandis leaves analyzed by light and electron microscopy showed that the B. octagenarum UFV-E1 filaments penetrate into the leaf mesophyll. The depth of infection and the mechanism by which the cyanobacterium invades leaf tissue were not determined. A major consequence of colonization by this cyanobacterium is a reduction in photosynthesis in the host since the cyanobacterial mats decrease the amount of light incident on leaf surfaces. Moreover, the cyanobacteria also interfere with stomatal gas exchange, decreasing CO2 assimilation. To our knowledge, this is the first report of an epiphytic cyanobacterial species causing damage to E. grandis leaves.

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