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Gerardo Zuniga - One of the best experts on this subject based on the ideXlab platform.

  • The Bark Beetle Dendroctonus Rhizophagus (Curculionidae: Scolytinae) Has Digestive Capacity to Degrade Complex Substrates: Functional Characterization and Heterologous Expression of an α-Amylase
    International Journal of Molecular Sciences, 2020
    Co-Authors: L. Viridiana Soto-robles, Claudia Cano-ramírez, María Fernanda López, Gabriel Obregón-molina, Verónica Torres-banda, Gerardo Zuniga
    Abstract:

    Dendroctonus-bark beetles are natural agents contributing to vital processes in coniferous forests, such as regeneration, succession, and material recycling, as they colonize and kill damaged, stressed, or old pine trees. These beetles spend most of their life cycle under stem and roots bark where they breed, develop, and feed on phloem. This tissue is rich in essential nutrients and complex molecules such as starch, cellulose, hemicellulose, and lignin, which apparently are not available for these beetles. We evaluated the digestive capacity of Dendroctonus Rhizophagus to hydrolyze starch. Our aim was to identify α-amylases and characterize them both molecularly and biochemically. The findings showed that D. Rhizophagus has an α-amylase gene (AmyDr) with a single isoform, and ORF of 1452 bp encoding a 483-amino acid protein (53.15 kDa) with a predicted signal peptide of 16 amino acids. AmyDr has a mutation in the chlorine-binding site, present in other phytophagous insects and in a marine bacterium. Docking analysis showed that AmyDr presents a higher binding affinity to amylopectin compared to amylose, and an affinity binding equally stable to calcium, chlorine, and nitrate ions. AmyDr native protein showed amylolytic activity in the head-pronotum and gut, and its recombinant protein, a polypeptide of ~53 kDa, showed conformational stability, and its activity is maintained both in the presence and absence of chlorine and nitrate ions. The AmyDr gene showed a differential expression significantly higher in the gut than the head-pronotum, indicating that starch hydrolysis occurs mainly in the midgut. An overview of the AmyDr gene expression suggests that the amylolytic activity is regulated through the developmental stages of this bark beetle and associated with starch availability in the host tree.

  • The Differential Expression of Mevalonate Pathway Genes in the Gut of the Bark Beetle Dendroctonus Rhizophagus (Curculionidae: Scolytinae) Is Unrelated to the de Novo Synthesis of Terpenoid Pheromones.
    International journal of molecular sciences, 2019
    Co-Authors: Laura Elisa Sarabia, Claudia Cano-ramírez, Guillermo Sanchez-martinez, María Fernanda López, Gabriel Obregón-molina, Gerardo Zuniga
    Abstract:

    Bark beetles commonly produce de novo terpenoid pheromones using precursors synthesized through the mevalonate pathway. This process is regulated by Juvenile Hormone III (JH III). In this work, the expression levels of mevalonate pathway genes were quantified after phloem feeding-to induce the endogenous synthesis of JH III-and after the topical application of a JH III solution. The mevalonate pathway genes from D. Rhizophagus were cloned, molecularly characterized, and their expression levels were quantified. Also, the terpenoid compounds produced in the gut were identified and quantified by Gas Chromatography Mass Spectrometry (GC-MS). The feeding treatment produced an evident upregulation, mainly in acetoacetyl-CoA thiolase (AACT), 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), phosphomevalonate kinase (PMK), and isopentenyl diphosphate isomerase (IPPI) genes, and males reached higher expression levels compared to females. In contrast, the JH III treatment did not present a clear pattern of upregulation in any sex or time. Notably, the genes responsible for the synthesis of frontalin and ipsdienol precursors (geranyl diphosphate synthase/farnesyl diphosphate synthase (GPPS/FPPS) and geranylgeranyl diphosphate synthase (GGPPS)) were not clearly upregulated, nor were these compounds further identified. Furthermore, trans-verbenol and myrtenol were the most abundant compounds in the gut, which are derived from an α-pinene transformation rather than de novo synthesis. Hence, the expression of mevalonate pathway genes in D. Rhizophagus gut is not directed to the production of terpenoid pheromones, regardless of their frequent occurrence in the genus Dendroctonus.

  • Degradation capacities of bacteria and yeasts isolated from the gut of Dendroctonus Rhizophagus (Curculionidae: Scolytinae)
    Folia Microbiologica, 2017
    Co-Authors: Carlos I. Briones-roblero, Roberto Rodríguez-díaz, José A. Santiago-cruz, Gerardo Zuniga, Flor N. Rivera-orduña
    Abstract:

    Bark beetles (Curculionidae: Scolytinae) feed on the xylem and phloem of their host, which are composed of structural carbohydrates and organic compounds that are not easily degraded by the insects. Some of these compounds might be hydrolyzed by digestive enzymes produced by microbes present in the gut of these insects. In this study, we evaluated the enzymatic capacity of bacteria ( Acinetobacter lwoffii , Arthrobacter sp., Pseudomonas putida , Pseudomonas azotoformans , and Rahnella sp.) and yeasts ( Candida piceae , Candida oregonensis , Cyberlindnera americana , Zygoascus sp., and Rhodotorula mucilaginosa ) isolated from the Dendroctonus Rhizophagus gut to hydrolyze cellulose, xylan, pectin, starch, lipids, and esters. All isolates, with the exception of C. piceae , showed lipolytic activity. Furthermore, P. putida , P. azotoformans , C. americana , C. piceae , and R. mucilaginosa presented amylolytic activity. Esterase activity was shown by A. lwoffii , P. azotoformans , and Rahnella sp. Cellulolytic and xylanolytic activities were present only in Arthrobacter sp. and P. azotoformans. The pectinolytic activity was not recorded in any isolate. This is the first study to provide evidence on the capacity of microbes associated with the D. Rhizophagus gut to hydrolyze specific substrates, which might cover part of the nutritional requirements for the development, fitness, and survival of these insects.

  • Comparison of orthologous cytochrome P450 genes relative expression patterns in the bark beetles Dendroctonus Rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae) during host colonization.
    Insect molecular biology, 2015
    Co-Authors: Gabriel Obregón-molina, María Fernanda López, Claudia Cano-ramírez, Ana K. Cesar-ayala, Gerardo Zuniga
    Abstract:

    Bark beetles of the genus Dendroctonus are important components of coniferous forests. During host colonization, they must overcome the chemical defences of their host trees, which are metabolized by cytochrome P450 (CYP or P450) enzymes to compounds that are readily excreted. In this study, we report the relative expression (quantitative real-time PCR) of four orthologous cytochrome P450 genes (CYP6BW5, CYP6DG1, CYP6DJ2 and CYP9Z20) in Dendroctonus Rhizophagus and Dendroctonus valens forced to attack host trees at 8 and 24 h following forced attack and in four stages during natural colonization [solitary females boring the bark (T1); both male and female members of couples before oviposition (T2); both male and female members of couples during oviposition (T3), and solitary females inside the gallery containing eggs (T4)]. For both species gene expression was different compared with that observed in insects exposed to single monoterpenes in the laboratory, and the expression patterns were significantly different amongst species, sex, gut region and exposure time or natural colonization stage. The induction of genes (CYP6BW5v1, CYP6DJ2v1 and CYP9Z20v1 from D. Rhizophagus, as well as CYP6DG1v3 from D. valens) correlated with colonization stage as well as with the increase in oxygenated monoterpenes in the gut of both species throughout the colonization of the host. Our results point to different functions of these orthologous genes in both species.

  • Comparative Study of the Antennae of Dendroctonus Rhizophagus and Dendroctonus valens (Curculionidae: Scolytinae): Sensilla Types, Distribution and Club Shape
    Annals of the Entomological Society of America, 2014
    Co-Authors: María Fernanda López, Francisco Armendáriz-toledano, Jorge E. Macías Sámano, Mineko Shibayama-salas, Gerardo Zuniga
    Abstract:

    We compared the antennae of two sibling bark beetle species, Dendroctonus Rhizophagus Thomas and Bright and Dendroctonus valens LeConte, to identify biologically and taxonomically relevant differences. Specifically, we characterized the diversity of sensilla types by using environmental scanning electron microscopy, quantified the abundance and distribution of the different types of sensilla on the antennal club, and characterized club shape through multivariate and geometric morphometric analyses. We identified four classes of sensilla in both species: chaetica, fluted, trichodea (three distinct types), and basiconica (long and short). ANOVA and MANOVA demonstrated that the number and distribution of sensilla with the potential for chemoreception (i.e., short and long basiconica) differed between species and sexes. Notably, the long sensilla basiconica in the third sensory band were clustered in D. Rhizophagus but not in D. valens. Geometric morphometric analysis using 27 landmarks showed that antennal club shape differed significantly between the two species and was not correlated with antennal size. The shape differences were associated with the number and distribution of sensilla.

Pierreemmanuel Courty - One of the best experts on this subject based on the ideXlab platform.

  • expression of major intrinsic protein genes in sorghum bicolor roots under water deficit depends on arbuscular mycorrhizal fungal species
    Soil Biology & Biochemistry, 2020
    Co-Authors: Sarah Symanczik, Jennifer Krutzmann, Uwe Nehls, Thomas Boller, Pierreemmanuel Courty
    Abstract:

    Abstract Drought is a limiting factor for crop plant production, especially in arid and semi-arid climates. In this study, sorghum (Sorghum bicolor) was inoculated with two arbuscular mycorrhizal fungi, either the standard Rhizophagus irregularis or the desert-adapted Rhizophagus arabicus, and grown in experimental microcosms under well-watered or drought conditions. We investigated gene expression of selected major intrinsic proteins (MIPs) of sorghum in these mycorrhizal plants in comparison to non-inoculated, well-watered controls. Colonization with R. irregularis resulted in the induction of the MIPs SbPIP2.2 and SbPIP2.5, regardless of whether sorghum plants were well watered or not. Root colonization with R. arabicus, however, caused an exclusive, strong reduction in the transcript levels of three MIP genes (SbTIP2.1, SbNIP1.2, SbNIP2.2) under drought conditions. . We also studied water transport properties of mycorrhiza-regulated MIPs. One particular MIP, SbPIP2.8, was found to mediate particularly high water permeability. Expression of this gene was strongly repressed upon drought, irrespectively on whether plants were mycorrhized or not.

  • Expression of major intrinsic protein genes in Sorghum bicolor roots under water deficit depends on arbuscular mycorrhizal fungal species
    Soil Biology and Biochemistry, 2020
    Co-Authors: Sarah Symanczik, Jennifer Krutzmann, Uwe Nehls, Thomas Boller, Pierreemmanuel Courty
    Abstract:

    Drought is a limiting factor for crop plant production, especially in arid and semi-arid climates. In this study, sorghum (Sorghum bicolor) was inoculated with two arbuscular mycorrhizal fungi, either the standard Rhizophagus irregularis or the desert-adapted Rhizophagus arabicus, and grown in experimental microcosms under well-watered or drought conditions. We investigated gene expression of selected major intrinsic proteins (MIPs) of sorghum in these mycorrhizal plants, compared to non-inoculated, well-watered sorghum (control). Colonization with R. irregularis induced the MIPs SbPIP2.2 and SbPIP2.5, regardless of whether sorghum plants were well watered or not. Root colonization with R. arabicus, however, caused an exclusive, strong reduction in the transcript levels of three MIP genes (SbTIP2.1, SbNIP1.2, SbNIP2.2) under drought conditions. We also studied water transport properties of mycorrhiza-regulated MIPs. One particular MIP, SbPIP2.8, was associated with high water permeability of roots. Expression of this gene was strongly repressed in all sorghum plants (mycorrhizal and non-inoculated) that experienced drought conditions.

  • Effects of two contrasted arbuscular mycorrhizal fungal isolates on nutrient uptake by Sorghum bicolor under drought
    Mycorrhiza, 2018
    Co-Authors: Sarah Symanczik, Thomas Boller, Moritz F. Lehmann, Andres Wiemken, Pierreemmanuel Courty
    Abstract:

    Drought is a limiting factor for crop production, especially in arid and semi-arid climates. In this study, Sorghum bicolor plants were inoculated, or not, with Rhizophagus irregularis, an arbuscular mycorrhizal (AM) strain typical for temperate climates, or Rhizophagus arabicus, a strain endemic to hyper-arid ecosystems. Plants were grown under well-watered or drought conditions in compartmented microcosms. Transpiration rates, plant growth, and nutrient uptake (using N-15 as a tracer) were determined to assess the impact of drought stress on sorghum plants in AM symbiosis. Although AM colonization did not affect the bulk biomass of host plants, R. arabicus improved their transpiration efficiency and drought tolerance more than R. irregularis. Moreover, R. arabicus was able to extract more N-15 from the soil under both water regimes, and AM-driven enhancement of the nitrogen and phosphorus content of sorghum, especially when water was limiting, was greater for R. arabicus-inoculated plants than for R. irregularis-inoculated plants. Our work demonstrates close links between AM hyphal phosphorus and nitrogen transport and uptake by AM plants for both AM fungal species. It also underscores that, under the drought stress conditions we applied, R. arabicus transfers significantly more nitrogen to sorghum than R. irregularis.

  • Plant identity and density can influence arbuscular mycorrhizal fungi colonization, plant growth, and reproduction investment in coculture
    Botany Botanique, 2015
    Co-Authors: Damien Derelle, Stéphane Declerck, Pierreemmanuel Courty, Isabelle Dajoz, Ingrid M. Van Aarle, David Carmignac, Patricia Genet
    Abstract:

    Reciprocal effects between arbuscular mycorrhizal fungi (AMF) and plant communities are essential to study the complexity of interactions in a grassland ecosystem. Here, we investigated the effects of plant community density and composition on AMF colonization, plant growth, and reproduction investment. We developed an experimental system with three compartments, each containing either three or six Medicago truncatula Gaertn. plants, or three M. truncatula plants associated with three Silene vulgaris (Moench) Garcke plants. All three compartments shared the same common mycorrhizal network built either by Rhizophagus irregularis MUCL 43194, by Rhizophagus clarus MUCL 46238, or by both AMF in association grown in a central compartment on Plantago lanceolata L. Our results demonstrate an absence of effect of plant density but a positive influence of mixed cultures on AMF root colonization compared with monocultures. This higher AMF development resulted in a positive feedback on shoot biomass and number of flowers and fruits produced by M. truncatula. Although both fungal strains were present in root systems, co-inoculation did not generate a synergistic effect on plant development. These results highlight the importance of plant associations on AMF dynamics, which requires further investigation at the community scale to improve our understanding of the intricate AMF - host plant relationships.

Dirk Redecker - One of the best experts on this subject based on the ideXlab platform.

Sarah Symanczik - One of the best experts on this subject based on the ideXlab platform.

  • expression of major intrinsic protein genes in sorghum bicolor roots under water deficit depends on arbuscular mycorrhizal fungal species
    Soil Biology & Biochemistry, 2020
    Co-Authors: Sarah Symanczik, Jennifer Krutzmann, Uwe Nehls, Thomas Boller, Pierreemmanuel Courty
    Abstract:

    Abstract Drought is a limiting factor for crop plant production, especially in arid and semi-arid climates. In this study, sorghum (Sorghum bicolor) was inoculated with two arbuscular mycorrhizal fungi, either the standard Rhizophagus irregularis or the desert-adapted Rhizophagus arabicus, and grown in experimental microcosms under well-watered or drought conditions. We investigated gene expression of selected major intrinsic proteins (MIPs) of sorghum in these mycorrhizal plants in comparison to non-inoculated, well-watered controls. Colonization with R. irregularis resulted in the induction of the MIPs SbPIP2.2 and SbPIP2.5, regardless of whether sorghum plants were well watered or not. Root colonization with R. arabicus, however, caused an exclusive, strong reduction in the transcript levels of three MIP genes (SbTIP2.1, SbNIP1.2, SbNIP2.2) under drought conditions. . We also studied water transport properties of mycorrhiza-regulated MIPs. One particular MIP, SbPIP2.8, was found to mediate particularly high water permeability. Expression of this gene was strongly repressed upon drought, irrespectively on whether plants were mycorrhized or not.

  • Expression of major intrinsic protein genes in Sorghum bicolor roots under water deficit depends on arbuscular mycorrhizal fungal species
    Soil Biology and Biochemistry, 2020
    Co-Authors: Sarah Symanczik, Jennifer Krutzmann, Uwe Nehls, Thomas Boller, Pierreemmanuel Courty
    Abstract:

    Drought is a limiting factor for crop plant production, especially in arid and semi-arid climates. In this study, sorghum (Sorghum bicolor) was inoculated with two arbuscular mycorrhizal fungi, either the standard Rhizophagus irregularis or the desert-adapted Rhizophagus arabicus, and grown in experimental microcosms under well-watered or drought conditions. We investigated gene expression of selected major intrinsic proteins (MIPs) of sorghum in these mycorrhizal plants, compared to non-inoculated, well-watered sorghum (control). Colonization with R. irregularis induced the MIPs SbPIP2.2 and SbPIP2.5, regardless of whether sorghum plants were well watered or not. Root colonization with R. arabicus, however, caused an exclusive, strong reduction in the transcript levels of three MIP genes (SbTIP2.1, SbNIP1.2, SbNIP2.2) under drought conditions. We also studied water transport properties of mycorrhiza-regulated MIPs. One particular MIP, SbPIP2.8, was associated with high water permeability of roots. Expression of this gene was strongly repressed in all sorghum plants (mycorrhizal and non-inoculated) that experienced drought conditions.

  • Effects of two contrasted arbuscular mycorrhizal fungal isolates on nutrient uptake by Sorghum bicolor under drought
    Mycorrhiza, 2018
    Co-Authors: Sarah Symanczik, Thomas Boller, Moritz F. Lehmann, Andres Wiemken, Pierreemmanuel Courty
    Abstract:

    Drought is a limiting factor for crop production, especially in arid and semi-arid climates. In this study, Sorghum bicolor plants were inoculated, or not, with Rhizophagus irregularis, an arbuscular mycorrhizal (AM) strain typical for temperate climates, or Rhizophagus arabicus, a strain endemic to hyper-arid ecosystems. Plants were grown under well-watered or drought conditions in compartmented microcosms. Transpiration rates, plant growth, and nutrient uptake (using N-15 as a tracer) were determined to assess the impact of drought stress on sorghum plants in AM symbiosis. Although AM colonization did not affect the bulk biomass of host plants, R. arabicus improved their transpiration efficiency and drought tolerance more than R. irregularis. Moreover, R. arabicus was able to extract more N-15 from the soil under both water regimes, and AM-driven enhancement of the nitrogen and phosphorus content of sorghum, especially when water was limiting, was greater for R. arabicus-inoculated plants than for R. irregularis-inoculated plants. Our work demonstrates close links between AM hyphal phosphorus and nitrogen transport and uptake by AM plants for both AM fungal species. It also underscores that, under the drought stress conditions we applied, R. arabicus transfers significantly more nitrogen to sorghum than R. irregularis.

Leif Martin Schroeder - One of the best experts on this subject based on the ideXlab platform.

  • population levels and flight phenology of bark beetle predators in stands with and without previous infestations of the bark beetle tomicus piniperda
    Forest Ecology and Management, 1999
    Co-Authors: Leif Martin Schroeder
    Abstract:

    Abstract Relative population levels and flight periods of Tomicus piniperda (L.) (Col.: Scolytidae) and two of its main predators, Thanasimus formicarius (L.) (Col.: Cleridae) and Rhizophagus depressus (F.) (Col.: Monotomidae) were monitored in 1995 in eight Scots pine stands in central Sweden using flight barrier traps (five per stand) baited with α-pinene and ethanol. In four of the stands (A-stands) T. piniperda and associated species had reproduced the previous year in stumps and slash remaining after thinnings conducted in the winter of 1993/1994. In the remaining four stands (B-stands) no bark beetle breeding material had been available during the five preceding years. In addition, the flight periods of the species were monitored in one stand in 1996. In 1995 the catches of T. piniperda and R. depressus were four to five times higher in the A-stands than in the B-stands, whereas there was no difference in the catch of T. formicarius between the two kinds of stands. The T. formicarius/T. piniperda ratio was ca. 50 times higher in the B-stands compared with the A-stands during the period of clerid predation on colonising bark beetle adults and six times higher during the period of clerid oviposition. The R. depressus/T. piniperda ratio was only slightly higher in the A-strands than in the B-stands as a result of the spatial distribution of T. piniperda. Three additional species of bark beetle predators were caught: Glischrochilus quadripunctatus (L.), Pityophagus ferrugineus (F.) (Col.: Nitidulidae) and Rhizophagus ferrugineus (Payk.) (Col.: Monotomidae). Based on their seasonal abundance the bark beetle predators can be divided into three temporal groups: the first species to occur in the spring is G. quadripunctatus, the second group consists of R. depressus and T. formicarius, and the last species to initiate flight are R. ferrugineus and P. ferrugineus.