Plant science Institute

Beltsville, MD, United States

Plant science Institute

Beltsville, MD, United States
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Bohbot J.D.,Plant science Institute | Dickens J.C.,Plant science Institute
Neuropharmacology | Year: 2012

The modulation of insect behavior for the purpose of controlling the spread of infectious diseases has been the task of a few insect repellents for which the mechanistic modes of action on odorant receptors (ORs) are unclear. Here, we study the effects of the repellents DEET and IR3535, and a novel OR co-receptor (Orco) agonist on odorant-evoked currents in Xenopus oocytes expressing two subtypes of Aedes aegypti ORs (AaORs). We show that DEET and IR3535 behave as insurmountable antagonists of ORs, and that modulation of OR activity is not restricted to antagonism and agonism, but also includes synergism. This knowledge of the molecular mechanisms underlying OR blockade, activation and hyperactivation will be fundamental to the development of novel strategies for the control of mosquito behavior. © 2012 Elsevier Ltd. All rights reserved.

Matsye P.D.,Mississippi State University | Lawrence G.W.,Mississippi State University | Youssef R.M.,Plant science Institute | Youssef R.M.,Fayoum University | And 4 more authors.
Plant Molecular Biology | Year: 2012

Transcriptional mapping experiments of the major soybean cyst nematode resistance locus, rhg1, identified expression of the vesicular transport machinery component, α soluble NSF attachment protein (α-SNAP), occurring during defense. Sequencing the α-SNAP coding regions from the resistant genotypes G. max[Peking/PI 548402] and G. max[PI 437654] revealed they are identical, but differ from the susceptible G. max[Williams 82/PI 518671] by the presence of several single nucleotide polymorphisms. Using G. max[Williams 82/PI 518671] as a reference, a G → T2,822 transversion in the genomic DNA sequence at a functional splice site of the α-SNAP[Peking/PI 548402] allele produced an additional 17 nucleotides of mRNA sequence that contains an in-frame stop codon caused by a downstream G → A2,832 transition. The G. max[Peking/PI 548402] genotype has cell wall appositions (CWAs), structures identified as forming as part of a defense response by the activity of the vesicular transport machinery. In contrast, the 17 nt α-SNAP[Peking/PI 548402] mRNA motif is not found in G. max[PI 88788] that exhibits defense to H. glycines, but lack CWAs. The α-SNAP[PI 88788] promoter contains sequence elements that are nearly identical to the α-SNAP[Peking/PI 548402] allele, but differs from the G. max[Williams 82/PI 518671] ortholog. Overexpressing the α-SNAP[Peking/PI 548402] allele in the susceptible G. max[Williams 82/PI 518671] genotype suppressed H. glycines infection. The experiments indicate a role for the vesicular transport machinery during infection of soybean by the soybean cyst nematode. However, increased GmEREBP1, PR1, PR2, PR5 gene activity but suppressed PR3 expression accompanied the overexpression of the α-SNAP[Peking/PI 548402] allele prior to infection. © 2012 Springer Science+Business Media B.V.

Shnaiderman C.,Israel Agricultural Research Organization | Shnaiderman C.,Hebrew University of Jerusalem | Miyara I.,Israel Agricultural Research Organization | Kobiler I.,Israel Agricultural Research Organization | And 2 more authors.
Molecular Plant-Microbe Interactions | Year: 2013

Ammonium secreted by the post-harvest pathogen Colletotrichum gloeosporioides during host colonization accumulates in the host environment due to enhanced fungal nitrogen metabolism. Two types of ammonium transporterencoding genes, AMET and MEP, are expressed during pathogenicity. Gene disruption of AMET, a gene modulating ammonia secretion, showed twofold reduced ammonia secretion and 45% less colonization on avocado fruit, suggesting a contribution to pathogenicity. MEPB, a gene modulating ammonium transport, is expressed by C. gloeosporioides during pathogenicity and starvation conditions in culture. Gene disruption of MEPB, the most highly expressed gene of the MEP family, resulted in twofold overexpression of MEPA and MEPC but reduced colonization, suggesting MEPB expression's contribution to pathogenicity. Analysis of internal and external ammonia accumulation by Δmep B strains in mycelia and germinated spores showed rapid uptake and accumulation, and reduced secretion of ammonia in the mutant versus wild-type (WT) strains. Ammonia uptake by the WT germinating spores but not by the Δmep B strain with compromised ammonium transport activated cAMP and transcription of PKA subunits PKAR and PKA2. Δmep B mutants showed 75% less appressorium formation and colonization than the WT, which was partially restored by 10 mM exogenous ammonia. Thus, whereas both AMET and MEPB genes modulate ammonia secretion, only MEPB contributes to ammonia accumulation by mycelia and germinating spores that activate the cAMP pathways, inducing the morphogenetic processes contributing to C. gloeosporioides pathogenicity. © 2013 The American Phytopathological Society.

Kula R.R.,Plant science Institute
Journal of Hymenoptera Research | Year: 2011

Two new species, Heterospilus belokobylskiji Kula, sp. n. and Heterospilus vincenti Kula, sp. n., from the Nearctic Region are described and dif erentiated from all other New World species of Doryctinae that exhibit brachyptery or aptery. They are the first brachypterous species of Heterospilus Haliday known in the New World and increase the total number of brachypterous species in the genus to four worldwide.

Bohbot J.D.,Plant science Institute | Dickens J.C.,Plant science Institute
PLoS ONE | Year: 2010

Background: DEET, 2-undecanone (2-U), IR3535 and Picaridin are widely used as insect repellents to prevent interactions between humans and many arthropods including mosquitoes. Their molecular action has only recently been studied, yielding seemingly contradictory theories including odorant-dependent inhibitory and odorant-independent excitatory activities on insect olfactory sensory neurons (OSNs) and odorant receptor proteins (ORs). Methodology/Principal Findings: Here we characterize the action of these repellents on two Aedes aegypti ORs, AaOR2 and AaOR8, individually co-expressed with the common co-receptor AaOR7 in Xenopus oocytes; these ORs are respectively activated by the odors indole (AaOR2) and (R)-(2)-1-octen3-ol (AaOR8), odorants used to locate oviposition sites and host animals. In the absence of odorants, DEET activates AaOR2 but not AaOR8, while 2-U activates AaOR8 but not AaOR2; IR3535 and Picaridin do not activate these ORs. In the presence of odors, DEET strongly inhibits AaOR8 but not AaOR2, while 2-U strongly inhibits AaOR2 but not AaOR8; IR3535 and Picaridin strongly inhibit both ORs. Conclusions/Significance: These data demonstrate that repellents can act as olfactory agonists or antagonists, thus modulating OR activity, bringing concordance to conflicting models.

Sanford J.L.,Plant science Institute | Sanford J.L.,Towson University | Shields V.D.C.,Towson University | Dickens J.C.,Plant science Institute
Naturwissenschaften | Year: 2013

Three gustatory receptor neurons were characterized for contact chemoreceptive sensilla on the labella of female yellow-fever mosquitoes, Aedes aegypti. The neuron with the smallest amplitude spike responded to the feeding deterrent, quinine, as well as N,N-diethyl-3-methylbenzamide and other insect repellents. Two other neurons with differing spikes responded to salt (NaCl) and sucrose. This is the first report of a gustatory receptor neuron specific for insect repellents in mosquitoes and may provide a tool for screening chemicals to discover novel or improved feeding deterrents and repellents for use in the management of arthropod disease vectors. © 2013 Springer-Verlag Berlin Heidelberg (outside the USA).

The Renodaeus group, a monophyletic assemblage of genera within the New World orthotyline tribe Ceratocapsini, comprising eight genera, including four new ones, is defined; and 48 species are treated, including 26 described as new and 12 transferred from Ceratocapsus Reuter as new combinations. Ceratocapsidea gen. n. is described to accommodate the new species C. bahamaensis sp. n., from the Bahamas; C. baranowskii sp. n., from Jamaica; C. dominicanensis sp. n., from the Dominican Republic; C. rileyi sp. n., from Texas; C. taeniola sp. n., from Jamaica; C. texensis sp. n., from Texas; C. transversa sp. n., from Mexico (Neuvo León); and C. variabilis sp. n., from Jamaica; and Ceratocapsus balli Knight, comb. n., C. complicatus Knight, comb. n., C. consimilis Reuter, comb. n., C. fusiformis Van Duzee, comb. n. (as the type species of the genus), C. nigropiceus Reuter, comb. n., and C. rufistigmus Blatchley, comb. n. [and a neotype designated], Ceratocapsus clavicornis Knight, syn. n. and C. divaricatus Knight, syn. n. are treated as junior synonyms of Ceratocapsus fusiformis Van Duzee. The genus Marininocoris Carvalho and the only included species M. myrmecoides Carvalho are redescribed. The genus Pilophoropsis Poppius is redescribed and revised, Renodaeus texanus Knight, comb. n. is transferred into it and the three new species P. bejeanae sp. n., from Sonora, Mexico; P. cunealis sp. n., from Oaxaca, Mexico; P. quercicola sp. n., from Arizona, USA, are described. Pilophoropsidea gen. n. is described to accommodate the 12 new species P. brailovskyi sp. n., from Federal District, Mexico; P. cuneata sp. n., from Chiapas, Mexico; P. dimidiata sp. n., from Durango, Mexico; P. fuscata sp. n., from Durango, Mexico and Arizona and New Mexico, USA; P. keltoni sp. n., from Durango, Mexico; P. maxima sp. n., from Durango, Mexico; P. pueblaensis sp. n., from Puebla, Mexico; P. schaffneri sp. n., from Neuvo León and San Luis Potosi, Mexico; P. serrata sp. n., from Michoacan, Mexico; P. touchetae sp. n., from Mexico (Puebla); P. truncata sp. n., from Mexico (Guerrero); P. tuberculata sp. n., from Mexico (Guerrero); and Ceratocapsus barberi Knight, comb. n., Ceratocapsus camelus Knight, comb. n. (as the type species of the genus), and Ceratocapsus fascipennis Knight, comb. n. Pilophoropsita gen. n. is described to accommodate P. schaffneri sp. n. from Costa Rica and Mexico (Jalisco, Nayarit, Oaxaca). The genus Renodaeus Distant is redescribed and the new species R. mimeticus sp. n. from Ecuador is described. The genus Zanchisme Kirkaldy is reviewed and the four known species are redescribed. Zanchismeopsidea gen. n. is described to accommodate Z. diegoi sp. n. from Argentina (Santiago del Estero). Provided are habitus illustrations for certain adults (Pilophoropsidea camelus, Pilophoropsis brachyptera Poppius, Renodaeus mimeticus, and Zanchisme mexicanus Carvalho & Schaffner), male and female (when available) color digital images and figures of male genitalia of all species, electron photomicrographs of diagnostic characters for selected species, and keys to the genera and their included species. The taxa treated in this paper are arranged alphabetically by genus and species. © Thomas J. Henry.

Otalora-Luna F.,Venezuelan Institute for Scientific Research | Dickens J.C.,Plant science Institute
PLoS ONE | Year: 2011

Orientation of insects to host plants and conspecifics is the result of detection and integration of chemical and physical cues present in the environment. Sensory organs have evolved to be sensitive to important signals, providing neural input for higher order multimodal processing and behavioral output. Here we report experiments to determine decisions made by Colorado potato beetle (CPB), Leptinotarsa decemlineata, in response to isolated stimuli and multimodal combinations of signals on a locomotion compensator. Our results show that in complete darkness and in the absence of other stimuli, pheromonal stimulation increases attraction behavior of CPB as measured in oriented displacement and walking speed. However, orientation to the pheromone is abolished when presented with the alternative stimulation of a low intensity yellow light in a dark environment. The ability of the pheromone to stimulate these diurnal beetles in the dark in the absence of other stimuli is an unexpected but interesting observation. The predominance of the phototactic response over that to pheromone when low intensity lights were offered as choices seems to confirm the diurnal nature of the insect. The biological significance of the response to pheromone in the dark is unclear. The phototactic response will play a key role in elucidating multimodal stimulation in the host-finding process of CPB, and perhaps other insects. Such information might be exploited in the design of applications to attract and trap CPB for survey or control purposes and other insect pests using similar orientation mechanisms.

Henry T.J.,Plant science Institute
Proceedings of the Entomological Society of Washington | Year: 2010

Thirty-two species of Miridae are recorded for the first time from West Virginia. With an additional six species reported in the literature and two subsequent synonymies since the 1983 "Annotated List..." by Wheeler, Mason, and Henry, 283 species of Miridae are now known from the state. The new records include six species in the subfamily Bryocorinae, two in Cylapinae, two in Deraeocorinae, twelve in Mirinae, seven in Orthotylinae, and three in Phylinae. Locality information, specific dates, associated host data, and number of specimens and sex are given for each species. Names used in the previous 1983 list are updated.

Ibrahim H.M.M.,Plant science Institute | Ibrahim H.M.M.,Cairo University | Hosseini P.,Towson University | Alkharouf N.W.,Towson University | And 4 more authors.
BMC Genomics | Year: 2011

Background: Root-knot nematodes are sedentary endoparasites that can infect more than 3000 plant species. Root-knot nematodes cause an estimated $100 billion annual loss worldwide. For successful establishment of the root-knot nematode in its host plant, it causes dramatic morphological and physiological changes in plant cells. The expression of some plant genes is altered by the nematode as it establishes its feeding site.Results: We examined the expression of soybean (Glycine max) genes in galls formed in roots by the root-knot nematode, Meloidogyne incognita, 12 days and 10 weeks after infection to understand the effects of infection of roots by M. incognita. Gene expression was monitored using the Affymetrix Soybean GeneChip containing 37,500 G. max probe sets. Gene expression patterns were integrated with biochemical pathways from the Kyoto Encyclopedia of Genes and Genomes using PAICE software. Genes encoding enzymes involved in carbohydrate and cell wall metabolism, cell cycle control and plant defense were altered.Conclusions: A number of different soybean genes were identified that were differentially expressed which provided insights into the interaction between M. incognita and soybean and into the formation and maintenance of giant cells. Some of these genes may be candidates for broadening plants resistance to root-knot nematode through over-expression or silencing and require further examination. © 2011 Ibrahim et al; licensee BioMed Central Ltd.

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