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BACKGROUND: Rhizoctonia solani (AG1 IA) is an important pathogen of rice (Oryza sativa L.) that causes rice sheath blight (RSB). Since control of RSB by breeding and fungicides have had limited success, novel strategies like biocontrol with plant growth-promoting rhizobacteria (PGPR) can be an effective alternative. METHOD AND RESULTS: Seven commonly used reference genes (RGs), 18SrRNA, ACT1, GAPDH2, UBC5, RPS27, eIF4a and CYP28, were evaluated for their stability in rice-R. solani-PGPR interaction for real-time quantitative PCR (RT-qPCR) analysis. Different algorithms were examined, Delta Ct, geNorm, NormFinder, BestKeeper, and comprehensive ranking by RefFinder, to evaluate RT-qPCR of rice in tissues infected with R. solani and treated with the PGPR strains, Pseudomonas saponiphilia and Pseudomonas protegens, with potassium silicate (KSi) alone or in combination with each PGPR strain. RG stability was affected for each treatment and treatment-specific RG selection was suggested. Validation analysis was done for nonexpressor of PR-1(NPR1) for each treatment. CONCLUSION: Overall, ACT1 was the most stable RG with R. solani infection alone, GAPDH2 with R. solani infection plus KSi, UBC5 with R. solani infection plus P. saponiphilia, and eIF4a with R. solani infection plus P. protegens. Both ACT1 and RPS27 were the most stable with the combination of KSi and P. saponiphilia, while RPS27 was the most stable with the combination of KSi and P. protegens.
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Oryza , Oryza/genética , Oryza/microbiologia , Melhoramento Vegetal , Rhizoctonia/genética , Desenvolvimento Vegetal , Doenças das Plantas/genética , Doenças das Plantas/microbiologiaRESUMO
Turcicum leaf blight (TLB) is a common foliar disease of maize in Mexico that is caused by the fungal pathogen Exserohilum turcicum. The most effective management strategy against TLB is monogenic race-specific resistance. Among the 140 E. turcicum isolates from symptomatic leaves collected from maize fields in Mexico, 100 were obtained from tropical (Veracruz) and temperate areas (Estado de México) between 2010 and 2019, and 40 isolates were obtained from tropical (Sinaloa, Tamaulipas, Veracruz, and Chiapas), subtropical (Nayarit, Jalisco, and Guanajuato), and temperate areas (Estado de Mexico, Hidalgo, and Puebla) collected in 2019. All the isolates caused TLB symptoms on the positive control (ht4), showing that they were all pathogenic. Six physiological races of E. turcicum (2, 3, 23, 3N, 23N, and 123N) were identified based on resistant or susceptible responses displayed by five maize differential genotypes (A619Ht1, A619Ht2, A619Ht3, B68HtN, and A619ht4). The most common was race 23, accounting for 68% of the isolates, followed by races 23N, 123N, 3, 2, and 3N at 15, 8, 6, 2, and 1%, respectively. Race 123N was able to infect the greatest number of maize differential genotypes used in the study. Race 123N was detected in Sinaloa and Estado de México. Race 3 was detected in Nayarit and Jalisco. Race 2 was detected in Jalisco, Estado de México, and Veracruz, and race 3N was detected in Tamaulipas. Race 23 was equally dominant in the tropical, subtropical, and temperate regions, while race 123N was more common in the tropical environment, and race 23N was more common in the tropical and temperate environments. There was no evidence for shifts in the races between 2010 and 2019.
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Doenças das Plantas , Zea mays , Zea mays/microbiologia , México , Doenças das Plantas/microbiologia , Meio AmbienteRESUMO
Varroa destructor is a damaging mite of Western honey bees (Apis mellifera). Genetic variability of the mite in different regions of the world could be related to the movement of infested bees or other factors, such as climate. In this study, V. destructor samples were collected from tropical and temperate climate regions of Mexico, and a humid continental climate region of Canada. COX-1 AFLPs showed that all the mites were the Korean haplotype. Four microsatellites revealed nine haplogroups from the continental climate region of Canada, compared to three haplogroups from the tropical and temperate climate regions of Mexico. CytII-ATP sequences showed seven haplogroups from the humid continental climate region vs. two haplogroups from the temperate region and one haplogroup from the tropical region. CytB sequences revealed seven haplogroups from Canada vs. three from Mexico. A comparison of the cytB sequences of the samples from Canada and Mexico to those from a worldwide collection showed that one sequence, designated the cytB1 type, predominated, comprising 57% of the 86 sequences; it clustered with similar sequences that comprised 80% of the sequences, designated family A. CytB1 was predominant in Mexico, but not in Canada. The other 20% of sequences were in families B and C, and all those samples originated from East and Southeast Asia. The microsatellite, cytII-ATP, and cytB markers, all showed higher variability in mites collected in Canada than in Mexico, which could be related to the cooler climate or an earlier invasion and/or multiple mite invasions in Canada.
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Varroidae , Humanos , Animais , Abelhas/genética , Varroidae/genética , México , Clima Tropical , Canadá , Trifosfato de AdenosinaRESUMO
Nosema ceranae is a microsporidian parasite that causes nosema disease, an infection of the honey bee (Apis mellifera) midgut. Two pathogen-associated molecular patterns (PAMPs), chitosan and peptidoglycan, and N. ceranae spores were fed to worker bees in sucrose syrup and compared to non-inoculated and N. ceranae-inoculated bees without PAMPs. Both chitosan and peptidoglycan significantly increased bee survivorship and reduced spore numbers due to N. ceranae infection. To determine if these results were related to changes in health status, expression of the immune-related genes, hymenoptaecin and defensin2, and the stress tolerance-related gene, blue cheese, was compared to that of control bees. Compared to the inoculated control, bees with the dose of chitosan that significantly reduced N. ceranae spore numbers showed lower expression of hymenoptaecin and defensin2 early after infection, higher expression mid-infection of defensin2 and lower expression of all three genes late in infection. In contrast, higher expression of defensin2 early in the infection and all three genes late in the infection was observed with peptidoglycan treatment. Changes late in the parasite multiplication stage when mature spores would be released from ruptured host cells are less likely to have contributed to reduced spore production. Based on these results, it is concluded that feeding bees chitosan or peptidoglycan can reduce N. ceranae infection, which is at least partially related to altering the health of the bee by inducing immune and stress-related gene expression.
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Abelhas/imunologia , Quitosana/administração & dosagem , Expressão Gênica/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Nosema/efeitos dos fármacos , Peptidoglicano/administração & dosagem , Animais , Abelhas/genética , Abelhas/microbiologia , Nosema/fisiologia , Estresse Fisiológico/efeitos dos fármacosRESUMO
Circulating hemocytes are responsible for defensive and healing mechanisms in the honey bee, Apis mellifera. Parasitism by the mite Varroa destructor and injection of V. destructor homogenate in buffer, but not buffer injection, showed similar reductions in total hemocyte concentrations in both Africanized and European adult honey bees. This indicated that compounds in V. destructor homogenate can have similar effects as V. destructor parasitism and that the response is not solely due to wounding. Samples from honey bees with different hemocyte concentrations were compared for the expression patterns of hemolectin (AmHml), prophenol oxidase (AmPpo), and class C scavenger receptor (AmSRC-C). Of the genes tested, only the expression of AmPpo correlated well with hemocyte counts for all the treatments, indicating that melanization is associated with those responses. Thus, the expression of AmPpo might be a suitable biomarker for hemocyte counts as part of cellular defenses against injection of buffer or mite compounds and V. destructor parasitism and perhaps other conditions involving healing and immunity.
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Abelhas/parasitologia , Catecol Oxidase/biossíntese , Precursores Enzimáticos/biossíntese , Hemócitos/fisiologia , Lectinas/biossíntese , Receptores Depuradores Classe C/biossíntese , Varroidae/fisiologia , Animais , Abelhas/genética , Expressão Gênica , Regulação da Expressão Gênica/genéticaRESUMO
Resveratrol is a polyphenolic compound produced in very low levels in grapes. To achieve high yield of resveratrol in wild grape, three Agrobacterium rhizogenes strains, Ar318, ArA4 and LBA9402, were used to induce hairy roots following infection of internodes, nodes or petioles of in vitro grown Vitis vinifera subsp. sylvesteris accessions W2 and W16, and cultivar Rasha. The effects of inoculation time, age of explants, bacterial concentration and co-cultivation times were examined on the efficiency of the production of hairy roots. Strains Ar318, ArA4 and LBA9402 all induced hairy roots in the tested genotypes, but the efficiency of ArA4 strain was higher than the other strains. The highest hairy root production was with using internodes as explants. The transformation of hairy roots lines was confirmed by PCR detection of rolB gene. Half Murashige and Skoog (MS) medium was better for biomass production compared with MS medium. HPLC analysis of resveratrol production in the hairy root cultures showed that all the genotypes produced higher amounts of resveratrol than control roots. The highest amount of resveratrol was produced from W16 internode cultures, which was 31-fold higher than that of control root. Furthermore, TLC analysis showed that treatments of hairy roots with sodium acetate and jasmonate elevated resveratrol levels both in hairy root tissue and excreted into the half MS medium. These results demonstrate that endogenous and exogenous factors can affect resveratrol production in hairy root culture of grape, and this strategy could be used to increase low resveratrol production in grapes.
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Agrobacterium/fisiologia , Estilbenos/metabolismo , Vitis/genética , Vitis/microbiologia , Biomassa , Técnicas de Cocultura , Meios de Cultura/química , Ciclopentanos/farmacologia , DNA de Plantas/análise , Genótipo , Técnicas In Vitro , Oxilipinas/farmacologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Resveratrol , Acetato de Sódio/farmacologia , Vitis/efeitos dos fármacos , Vitis/crescimento & desenvolvimentoRESUMO
For the first time, adults and brood of Africanized and European honey bees (Apis mellifera) were compared for relative virus levels over 48 h following Varroa destructor parasitism or injection of V. destructor homogenate. Rates of increase of deformed wing virus (DWV) for Africanized versus European bees were temporarily lowered for 12h with parasitism and sustainably lowered over the entire experiment (48 h) with homogenate injection in adults. The rates were also temporarily lowered for 24h with parasitism but were not affected by homogenate injection in brood. Rates of increase of black queen cell virus (BQCV) for Africanized versus European bees were similar with parasitism but sustainably lowered over the entire experiment with homogenate injection in adults and were similar for parasitism and homogenate injection in brood. Analyses of sac brood bee virus and Israeli acute paralysis virus were limited as detection did not occur after both homogenate injection and parasitism treatment, or levels were not significantly higher than those following control buffer injection. Lower rates of replication of DWV and BQCV in Africanized bees shows that they may have greater viral resistance, at least early after treatment.
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Vetores Artrópodes/virologia , Abelhas/virologia , Varroidae/virologia , Replicação Viral , Animais , Vetores Artrópodes/fisiologia , Abelhas/parasitologia , Dicistroviridae/patogenicidade , Dicistroviridae/fisiologia , Resistência à Doença , Comportamento Alimentar , Interações Hospedeiro-Parasita , Picornaviridae/patogenicidade , Picornaviridae/fisiologia , Varroidae/fisiologiaRESUMO
Honey bees (Apis mellifera) provide a useful model for studying aging because of the differences in longevity between the relatively short-lived summer and long-lived winter bees, as well as bees lacking signs of cognitive senescence as they age. Bee brains were dissected from newly emerged, 14-day-, and 28-day- old bees in mid- and late summer, as well as brood nest bees in fall, winter, and spring, before, during, and after overwintering, respectively. Brains were examined with nuclear magnetic resonance (NMR) spectroscopy to analyze their metabolome. Nine variable importance in projection (VIP) variables were identified, primarily amino acids and choline derivatives. Differences in metabolite concentrations were found with different ages of summer bees, mostly between newly emerged and 14-day- old bees, such as a decrease in phenylalanine and an increase in ß-alanine, but there were also changes in older adults, such as o-phosphocholine that declined in 28-day- old bees. Differences in brood nest bees were observed, including a decline in tryptophan and an increase in ß-alanine. These may provide distinct metabolomic signatures with age and season. Such research holds promise for a better understanding of the complex interplays between bee physiology, development, and aging, which has implications for improving bee health and management.
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American ginseng (Panax quinquefolius) is widely used due to its medicinal properties. Ontario is a major producer of cultivated American ginseng, where seeds were originally collected from the wild without any subsequent scientific selection, and thus the crop is potentially very diverse. A collection of 162 American ginseng plants was harvested from a small area in a commercial garden and phenotyped for morphological traits, such as root grade, stem length, and fresh and dry weights of roots, leaves, stems, and seeds. All of the traits showed a range of values, and correlations were observed between root and stem weights, root dry weight and leaf dry weight, as well as root and leaf fresh weights. The plants were also genotyped using single nucleotide polymorphisms (SNPs) at the PW16 locus. SNP analysis revealed 22 groups based on sequence relatedness with some groups showing no SNPs and others being more diverse. The SNP groups correlated with significant differences in some traits, such as stem length and leaf weight. This study provides insights into the genetic and phenotypic diversity of cultivated American ginseng grown under similar environmental conditions, and the relationship between different phenotypes, as well as genotype and phenotype, will aid in future selection programs to develop American ginseng cultivars with desirable agronomic traits.
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Transposon mutagenesis screening of Bacillus subtilis YB-1471, a novel rhizosphere biocontrol agent of Fusarium crown rot (FCR) of wheat, resulted in the identification of orf04391, linked to reduced biofilm formation. The gene encodes a protein possessing a putative tertiary structure of a "double-wing" DNA-binding domain. Expression of orf04391 increased during biofilm development in stationary cultures and during rapid growth in shaking cultures. An orf04391 deletion strain showed reduced biofilm production related to lower levels of the extracellular matrix, and the mutant also had reduced sporulation, adhesion, root colonization, and FCR biocontrol efficiency. Transcriptome analysis of YB-1471 and Δorf04391 in stationary culture showed that the loss of orf04391 resulted in altered expression of numerous genes, including sinI, an initiator of biofilm formation. DNA binding was shown with his-tagged Orf04391 binding to the sinIR operon in vivo and in vitro. Orf04391 appears to be a transcriptional regulator of biofilm formation in B. subtilis through the Spo0A-SinI/SinR pathway.
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Panax quinquefolius shows much higher mortality to Ilyonectria mors-panacis root rot when grown in soil previously planted with ginseng than in soil not previously planted with ginseng, which is known as ginseng replant disease. Treatment of ginseng roots with methanol extracts of previous ginseng soils significantly increased root lesion sizes due to I. mors-panacis compared to roots treated with water or methanol extracts of ginseng roots or non-ginseng soils. Inoculation of water-treated roots with I. mors-panacis increased expression of a basic chitinase 1 gene (PqChi-1), neutral pathogenesis-related protein 5 gene (PqPR5) and pathogenesis-related protein 10-2 gene (PqPR10-2), which are related to jasmonic acid (JA), ethylene (ET) or necrotrophic infection, and also increased expression of an acidic ß-1-3-glucanase gene (PqGlu), which is related to salicylic acid (SA). Infection did not affect expression of a cysteine protease inhibitor gene (PqCPI). Following infection, roots treated with ginseng root extract mostly showed similar expression patterns as roots treated with water, but roots treated with previous ginseng soil extract showed reduced expression of PqChi-1, PqPR5, PqPR10-2 and PqCPI, but increased expression of PqGlu. Methanol-soluble compound(s) in soil previously planted with ginseng are able to increase root lesion size, suppress JA/ET-related gene expression and trigger SA-related gene expression in ginseng roots during I. mors-panacis infection, and may be a factor contributing to ginseng replant disease.
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Ginsenosides are saponins that possess a sugar moiety attached to a hydrophobic aglycone triterpenoid. They have been widely studied for their various medicinal benefits, such as their neuroprotective and anti-cancer activities, but their role in the biology of ginseng plants has been much less widely documented. In the wild, ginsengs are slow-growing perennials with roots that can survive for approximately 30 years; thus, they need to defend themselves against many potential biotic stresses over many decades. Biotic stresses would be a major natural selection pressure and may at least partially explain why ginseng roots expend considerable resources in order to accumulate relatively large amounts of ginsenosides. Ginsenosides may provide ginseng with antimicrobial activity against pathogens, antifeedant activity against insects and other herbivores, and allelopathic activity against other plants. In addition, the interaction of ginseng with pathogenic and non-pathogenic microorganisms and their elicitors may trigger increases in different root ginsenosides and associated gene expression, although some pathogens may be able to suppress this behavior. While not covered in this review, ginsenosides also have roles in ginseng development and abiotic stress tolerance. This review shows that there is considerable evidence supporting ginsenosides as important elements of ginseng's defense against a variety of biotic stresses.
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Introduction: Natural weed cover and a legume cover crop were examined to determine if they could impact soil fungal diversity as an indicator of soil quality in banana production. Methods: Banana in Yunnan Province, China, was grown under three treatments: conventional tillage (bare soil), natural weed cover (primarily goosegrass (Eleusine indica (L.) Gaerth)), or a cover crop (Siratro (Macroptilium atropurpureum (DC.) Urb.)). Analysis of the soil fungal communities between 2017 and 2020 was done by Illumina Miseq high-throughput sequencing. Results: Most significant effects were in the intercropping area for the treatments, whereas it was rarely observed in the furrow planted with banana. Based on the Shannon and Simpson diversity indices, soil fungal diversity in the intercropping area significantly decreased following planting banana in 2017 with all three treatments. However, both the Shannon and Simpson diversity indices showed that there were significant increases in fungal soil diversity in 2019 and 2020 with natural weed cover or Siratro compared to bare soil. At the end of the experiment, significant increases in fungal genera with Siratro compared to bare soil were observed with Mortierella, Acremonium, Plectophaerella, Metarhizium and Acrocalymma, and significant decreases were observed with Fusicolla, Myrothecium, Exserohilum, Micropsalliota and Nigrospora. Siratro resulted in higher stability of the soil fungal microbiome by increasing the modularity and the proportion of negative co-occurrences compared to bare soil. For fungal guilds, Siratro significantly increased saprotrophs_symbiotrophs in 2019 and 2020 and significantly decreased pathogens_saprotrophs in 2020 compared to bare soil. Discussion: Using Siratro as a cover crop in the intercropping area of banana helped maintain soil fungal diversity, which would be beneficial for soil health with more symbiotrophs and less pathogens in the soil. However, further research is needed to determine the long-term impact of weed or Siratro cover crop on the fungal soil ecosystem and growth of banana.
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Fusarium crown rot (FCR) caused by Fusarium pseudograminearum is one of the most serious soil-borne diseases of wheat. Among 58 bacterial isolates from the rhizosphere soil of winter wheat seedlings, strain YB-1631 was found to have the highest in vitro antagonism to F. pseudograminearum growth. LB cell-free culture filtrates inhibited mycelial growth and conidia germination of F. pseudograminearum by 84.14% and 92.23%, respectively. The culture filtrate caused distortion and disruption of the cells. Using a face-to-face plate assay, volatile substances produced by YB-1631 inhibited F. pseudograminearum growth by 68.16%. In the greenhouse, YB-1631 reduced the incidence of FCR on wheat seedlings by 84.02% and increased root and shoot fresh weights by 20.94% and 9.63%, respectively. YB-1631 was identified as Bacillus siamensis based on the gyrB sequence and average nucleotide identity of the complete genome. The complete genome was 4,090,312 bp with 4357 genes and 45.92% GC content. In the genome, genes were identified for root colonization, including those for chemotaxis and biofilm production, genes for plant growth promotion, including those for phytohormones and nutrient assimilation, and genes for biocontrol activity, including those for siderophores, extracellular hydrolase, volatiles, nonribosomal peptides, polyketide antibiotics, and elicitors of induced systemic resistance. In vitro production of siderophore, ß-1, 3-glucanase, amylase, protease, cellulase, phosphorus solubilization, and indole acetic acid were detected. Bacillus siamensis YB-1631 appears to have significant potential in promoting wheat growth and controlling wheat FCR caused by F. pseudograminearum.
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Reactive oxygen species (ROS), produced by NADPH oxidases known as RBOHs in plants, play a key role in plant development, biotic and abiotic stress responses, hormone signaling, and reproduction. Among the subfamily of receptor-like kinases referred to as CrRLK, there is FERONIA (FER), a regulator of RBOHs, and FER requires a GPI-modified membrane protein produced by LORELEI (LRE) or LORELEI-like proteins (LLG) to reach the plasma membrane and generate ROS. In Arabidopsis, AtLLG1 is involved in interactions with microbes as AtLLG1 interacts with the flagellin receptor (FLS2) to trigger the innate immune response, but the role of LLGs in mutualistic interactions has not been examined. In this study, two Phaseolus vulgaris LLG genes were identified, PvLLG2 that was expressed in floral tissue and PvLLG1 that was expressed in vegetative tissue. Transcripts of PvLLG1 increased during rhizobial nodule formation peaking during the early period of well-developed nodules. Also, P. vulgaris roots expressing pPvLLG1:GFP-GUS showed that this promoter was highly active during rhizobium infections, and very similar to the subcellular localization using a construct pLLG1::PvLLG1-Neon. Compared to control plants, PvLLG1 silenced plants had less superoxide (O2-) at the root tip and elongation zone, spotty hydrogen peroxide (H2O2) in the elongation root zone, and significantly reduced root hair length, nodule number and nitrogen fixation. Unlike control plants, PvLLG1 overexpressing plants showed superoxide beyond the nodule meristem, and significantly increased nodule number and nodule diameter. PvLLG1 appears to play a key role during this mutualistic interaction, possibly due to the regulation of the production and distribution of ROS in roots.
Assuntos
Phaseolus , Rhizobium tropici , Rhizobium , Rhizobium tropici/genética , Rhizobium tropici/metabolismo , Nódulos Radiculares de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/metabolismo , Peróxido de Hidrogênio/metabolismo , Simbiose/genética , Rhizobium/genética , Raízes de Plantas/metabolismoRESUMO
Rice (Oryza sativa) cv. Nipponbare expresses non-host resistance (NHR) to the wheat leaf rust fungus, Puccinia triticina f. sp. tritici (Ptt). When the leaves of cv. Nipponbare were inoculated with Ptt, approx 93% of the urediniospores germinated on the leaf surface, but only 10% of the germinated spores formed appressoria over the stomata at one day post inoculation (1 dpi). Hydrogen peroxide (H(2)O(2)) accumulated in host cells around the appressoria at 3 dpi. Approx. 3% of the appressoria produced short hyphae inside the leaf, and fluorescence was observed in tissue invaded by the hyphae by 7 dpi. At 22 dpi, 0.2% of the sites with appressoria formed branching infection hypha in mesophyll cells, but no substomatal vesicles, haustorial mother cells or haustoria were observed. Proteins were extracted from leaves 3 dpi and analyzed by two-dimensional gel electrophoresis (2-DE). A total 33 spots were reproducibly up-regulated and 9 were down-regulated by infection compared to the water inoculated control. Of these, 30 were identified by MALDI-TOF Mass Spectrometry. The identified proteins participate in defense/stress responses, energy/carbohydrate metabolism, oxidation-reduction processes, protein folding/turnover/cleavage/degradation, signal transduction and cell death regulation. The results indicates that NHR of rice to Ptt is consistent with a shift in protein and energy metabolism, increased antimicrobial activities, possibly including phytoalexin accumulation and cell wall reinforcement, increased cell repair, antioxidive and detoxification reactions, and enhanced prevention of plant cell death. Nearly half of the up-regulated identified proteins were associated with chloroplast and mitochondrial physiology suggesting important roles for these organelles during NHR.
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Basidiomycota/patogenicidade , Oryza/fisiologia , Doenças das Plantas/imunologia , Imunidade Vegetal , Proteômica , Basidiomycota/crescimento & desenvolvimento , Parede Celular/metabolismo , Parede Celular/microbiologia , Regulação para Baixo , Eletroforese em Gel Bidimensional , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Hifas , Microscopia Eletrônica de Varredura , Oryza/imunologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Esporos Fúngicos , Coloração e Rotulagem , Triticum/microbiologia , Regulação para CimaRESUMO
Three isolates of each of the entomopathogenic fungi, Metarhizium anisopliae, Beauveria bassiana and Clonostachys rosea, were assessed for their pathogenicity to the honey bee parasitic mite, Varroa destructor. The fungi were applied to varroa mites by immersing them in a spore solution, and then the inoculated mites were placed on honey bee brood inside capped cells. At 7 days post inoculation (dpi), the three fungi caused significant varroa mortality compared to non-inoculated mites. In brood treated only with varroa mites, expression of the honey bee genes, hymenoptaecin and poly U binding factor 68 Kd (pUf68), decreased over time, while expression of blue cheese (BlCh) and single minded (SiMd) was not affected. In brood inoculated directly only with M. anisopliae or B. bassiana, the emerged adults showed reduced weight indicating infection by the fungi, which was confirmed by observation of hyphae in the brood. Fungal infection of the brood resulted in increased expression of hymenoptaecin, pUf68 and BlCh, but not SiMd. In brood treated with varroa mites that had been inoculated with the fungi, expression of hymenoptaecin, pUf68 and BlCh, but not SiMd, was even more up-regulated. While varroa mites can suppress gene expression in honey bee brood, varroa mites infected with entomopathogenic fungi induced their expression. This may be due to a low level of fungal infection of the bee, which negated the immunosuppression by the mites. Therefore, entomopathogenic fungi could reduce varroa mite damage to honey bee brood by both infecting the parasite and preventing varroa-associated suppression of honey bee immunity.
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Abelhas/imunologia , Agentes de Controle Biológico , Interações Hospedeiro-Parasita/imunologia , Varroidae/microbiologia , Animais , Beauveria/patogenicidade , Abelhas/genética , Abelhas/microbiologia , Abelhas/parasitologia , Regulação da Expressão Gênica , Interações Hospedeiro-Parasita/genética , Hypocreales/patogenicidade , Imunidade Inata , Metarhizium/patogenicidadeRESUMO
One hundred and fifty soil samples collected from different crop fields in southern Ontario, Canada were screened to obtain microorganisms capable of transforming deoxynivalenol (DON) to de-epoxy DON (dE-DON). Microbial DON to dE-DON transformation (i.e. de-epoxydation) was monitored by using liquid chromatography-ultraviolet-mass spectrometry (LC-UV-MS). The effects of growth substrates, temperature, pH, incubation time and aerobic versus anaerobic conditions on the ability of the microbes to de-epoxydize DON were evaluated. A mixed microbial culture from one composite soil sample showed 100% DON to dE-DON biotransformation in mineral salts broth (MSB) after 144 h of incubation. Treatments of the culture with selective antibiotics followed an elevated temperature (50°C) for 1.5 h considerably reduced the microbial diversity. Partial 16S-rRNA gene sequence analysis of the bacteria in the enriched culture indicated the presence of at least six bacterial genera, namely Serratia, Clostridium, Citrobacter, Enterococcus, Stenotrophomonas and Streptomyces. The enriched culture completely de-epoxydized DON after 60 h of incubation. Bacterial de-epoxydation of DON occurred at pH 6.0-7.5, and a wide array of temperatures (12-40°C). The culture showed rapid de-epoxydation activity under aerobic conditions compared to anaerobic conditions. This is the first report on microbial DON to dE-DON transformation under aerobic conditions and moderate temperatures. The culture could be used to detoxify DON contaminated feed and might be a potential source for gene(s) for DON de-epoxydation.
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Microbiologia do Solo , Tricotecenos/metabolismo , Tricotecenos/toxicidade , Animais , Bactérias Aeróbias/genética , Bactérias Aeróbias/isolamento & purificação , Bactérias Aeróbias/metabolismo , Bactérias Anaeróbias/genética , Bactérias Anaeróbias/isolamento & purificação , Bactérias Anaeróbias/metabolismo , Biotransformação , Contaminação de Alimentos/prevenção & controle , Genes Bacterianos , Humanos , Inativação Metabólica , Ontário , RNA Bacteriano/genética , RNA Ribossômico 16S/genéticaRESUMO
The endosphere of ginseng contains a variety of fungal, bacterial, archaeal and viral endophytes. Bacterial endophytes are primarily members of the Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, and fungal endophytes are primarily members of the Ascomycota, Zygomycota and Basidiomycota. Although archaea and viruses have been detected in symptomless ginseng plants, little is known about them. Many but not all studies have shown roots having the highest abundance and diversity of bacterial and fungal endophytes, with some endophytes showing specificity to above or belowground tissues. Abundance often increases with root age, although diversity can decrease, possibly related to increases in potential latent fungal pathogen infections. The descriptions of many endophytes that can metabolize ginsenosides indicate an adaptation of the microbes to the unique combination of secondary metabolites found in ginseng tissues. Most research on the benefits provided by bacterial and fungal endophytes has concentrated on improved plant nutrition, growth promotion and increased disease resistance, but little on their ability to increase abiotic stress resistance. Some other areas where more research is needed is field trials with endophyte-treated plants grown in various environments, genomic/metagenomic analysis of endophytes, and the effects of endophytes on induced disease resistance and abiotic stress tolerance.