|Title:||Genetics, Population Dynamics, and Mycotoxin Prevention in Peanut|
|Objective:||1. Determine the population dynamics of sexually reproducing Aspergillus flavus under field conditions.
2. Identify genes in Aspergillus flavus responsible for virulence during the infection process and elucidate the role of fungal gene products for overcoming peanut resistance mechanisms.
3. Determine the role of defensive peanut phytoalexins in mediating natural crop resistance against Aspergillus flavus.
Sclerotia of A. flavus will be collected from corn grown in a randomized complete block design consisting of four overhead irrigation treatments to provide different degrees of drought stress. Experiments involving natural field populations of A. flavus will be conducted during years 1 and 2. The same procedure will be repeated for years 3 and 4, except that corn ears will be sprayed with a conidial suspension of a non-toxigenic biocontrol strain (NRRL 21882 [from Afla-GuardÂ® ] or AF36). Sclerotia will incubated on the surface of nonsterile soil (100% relative humidity) for 5-7 months. Ascospores from fertile sclerotia will be germinated to obtain progeny strains. To detect genetic recombination, total genomic DNA will be isolated from progeny strains. Recombination events due to independent assortment of chromosomes and crossing over will be detected by multilocus sequence typing (MLST) and linkage disequilibrium/compatibility analyses. Genes encoding putative phytoalexin-detoxification enzymes (PDEs) will be cloned from pathogenic A. flavus strains. PDE production by A. flavus will be induced in culture by the presence of purified peanut phytoalexins or peanut seeds. cDNA libraries will be generated and used as templates to amplify candidate genes by Polymerase Chain Reaction (PCR). Native in vitro-expressed proteins will be purified and their activity will be tested against a variety of purified peanut phytoalexins. Liquid chromatographic-tandem mass spectrometric (LC-MS) analysis of the phytoalexin samples after exposure to the various purified proteins will be used to detect potential enzymatic modifications of the phytoalexin compounds. Target PDEs will be analyzed from different genotypes of A. flavus and A. parasiticus to assess the genetic variability of these enzymes and thus predict the potential effectiveness of PDE inhibitors. A model system will be developed to screen PDE inhibitors. Pathogenicity tests will be conducted on single peanut seeds inoculated with A. flavus after the application of inhibitory compounds. The bioactivity of phytoalexins will be assayed against economically important plant pathogenic fungi grown on micro-plates. The dynamics of phytoalexin formation will be studied by first determining the most fungal-resistant (high phytoalexin producers) and fungal-susceptible (low phytoalexin producers) peanut genotypes from a core collection of 108 genotypes. Peanut seeds from genotypes will be subjected to different biotic and abiotic elicitors to elucidate changes in the composition of phytoalexins and to detect possible degradation products due to detoxification. The embryos and cotyledons from seeds will be wounded and inoculated with fungi and bacteria, then extracted and analyzed with high performance liquid chromatography (HPLC)/MS. Data obtained from analyses of the core collection of peanut genotypes will be used to identify peanut germplasm with disease resistance. To further examine phytoalexin detoxification (degradation) products, feeding experiments will be conducted in which fungi and bacteria are fed peanut phytoalexins followed by HPLC/MS/Nuclear Magnetic Resonance analysis.
|Funding Source:||United States Department of Agriculture (USDA), Agricultural Research Service (ARS)|
|Institutions:||USDA/ARS - South Atlantic Area|
ARS (NP 108):
Potential involvement of Aspergillus flavus Link laccases in peanut invasion at low water potential
Arias De Ares RS, Sobolev V, Orner VA, Dang PM, Lamb MC .
Plant Pathol. 2014 Apr;63(2):354–64.
Potential involvement of Aspergillus flavus laccases in peanut invasion at low water potential
Arias RS, Sobolev VS, Orner VA, Dang PM, Lamb MC.
Plant Pathol. 2014 Apr;63(2):354-64.
Sexual reproduction in Aspergillus flavus sclerotia naturally produced in corn
Horn BW, Sorensen RB, Lamb MC, Sobolev VS, Olarte RA, Worthington CJ, Carbone I.
Phytopathology. 2014 Jan;104(1):75-85.
Distribution of bacterial endophytes in peanut seeds obtained from axenic and control plant material under field conditions
Sobolev V, Orner VA, Arias De Ares RS .
Plant Soil. 2013 Oct;371(1):367-76.
Sexual reproduction in Aspergillus tubingensis from section Nigri
Horn BW, Olarte RA, Peterson SW, Carbone I.
Mycologia. 2013 Sep;105(5):1153-63.
First report of Pantoea ananatis (Syn. Erwinia uredovora) associated with peanut rust in Georgia
Arias De Ares RS, Power I, Culbreath AK, Sobolev V, Lamb MC .
Plant Health Prog. 2013 Jul;:.
First report of Pantoea ananatis (Syn. Erwinia uredovora) being associated with peanut rust in Georgia
Arias RS, Power IL, Culbreath AK, Sobolev VS, Lamb MC.
Plant Health Prog. 2013 Jul. [Epub ahead of print]
WUS and STM-based reporter genes for studying meristem development in poplar
Bao Y, Dharmawardhana P, Arias R, Allen MB, Ma C, Strauss SH.
Plant Cell Rep. 2009 Jun;28(6):947-62.
Genetic polymorphism of Puccinia arachidis - (Abstract Only)
Power, I.L., Arias De Ares, R.S., Culbreath, A.K. 2013. Genetic polymorphism of Puccinia arachidis. Phytopathology. 103(Suppl. 2):S2.115. APS-MSA Joint Meeting. Austin, Texas. August 10â€“14, 2013
Experimental Study of Combustion and Emissions Characteristics of Methyl Oleate, as a Surrogate for Biodiesel, in a Direct injection Diesel Engine - (Proceedings)
Molecular markers and strategies to control aflatoxin in peanut - (Other)
Arias De Ares, R.S. 2013. Molecular markers and strategies to control aflatoxin in peanut. Valdosta State University. 03-07-2013. Oral Presentation.
Population shifts and mating-type heterokaryosis in Aspergillus flavus - (Abstract Only)
Olarte, R.A., Horn, B.W., Worthington, C.J., Singh, R., Carbone, I. 2013. Population shifts and mating-type heterokaryosis in Aspergillus flavus. 9th International Aspergillus Meeting. March 11-12, 2013. Pacific Grove, CA.
Clonality and sex impact aflatoxigenicity in Aspergillus populations - (Abstract Only)
Carbone, I., Horn, B.W., Olarte, R.A., Moore, G.G., Worthington, C.J., Monacell, J.T., Singhi, R., Stone, E.A., Hell, K., Chulze, S.N., Barros, G., Wright, G., Naik, M.K. 2013. Clonality and sex impact aflatoxigenicity in Aspergillus populations. Fungal Genetics Conference. Pacific Grove, CA. March 12-17, 2013.
Molecular Diversity of the peanut rust pathogen and its host - (Abstract Only)
Power, I.L., Tillman, B.L., Holbrook Jr, C.C., Ozias-Akins, P., Chu, Y., Arias De Ares, R.S., Culbreath, A.K. 2013. Molecular Diversity of the peanut rust pathogen and its host. Phytopathology 103(Suppl.1): S1.9. APS-Southern Division Meeting. Feb. 08-10,2013. Baton Rouge, LA.
Effect of sexual recombination on population diversity in aflatoxin production by Aspergillus flavus - (Abstract Only)
Olarte, R.A., Horn, B.W., Dorner, J.W., Monacell, J.T., Singh, E.A., Carbone, I. 2013. Effect of sexual recombination on population diversity in aflatoxin production by Aspergillus flavus. American Phytopathogical Society Southern Division Annual Meeting. Feb. 8-10, 2013. Baton Rouge, LA.
Mating-type heterokaryosis in Aspergillus flavus in North Carolina - (Abstract Only)
Olarte, R.A., Horn, B.W., Worthington, C.J., Carbone, I. 2012. Mating-type heterokaryosis in Aspergillus flavus in North Carolina. MycoRed North America. June 24-28, 2012. Ottawa, Canada.
Microsatellite markers in plant pathogenic fungi - (Abstract Only)
Arias, R.S., Ray, J.D., Mengistu, A., Glynn, N.C., Scheffler, B.E. 2012. Microsatellite markers in plant pathogenic fungi. Meeting Proceedings.
Molecular tools used in agriculture - (Other)
Arias, R.S. 2011. Molecular tools used in agriculture. Albany State University. October 31, 2011. Meeting Proceedings.
Upic + Go: Zeroing in on Informative Markers - (Other)
Ford, D., Arias, R.S., Ballard, L.L., Scheffler, B.E., Duke, M.V., Simpson, S.A., Newsome, A. 2010. UPIC + GO: Zeroing in on informative markers. Eighth Annual Rocky Mountain Bioinformatics Conference, International Society of Computational Biology (ISCB), December 09-11, 2010, Aspen, CO. Meeting Proceedings.
Development of SSR markers for Chionanthus retusus (Oleaceae) and effective discrimination of closely related taxa - (Other)
Arias, R.S., Techen, N., Rinehart, T.A., Olsen, R.T., Kirkbride, J.H., Scheffler, B.E. 2009. Development of SSR markers for Chionanthus retusus (Oleaceae) and effective discrimination of closely related taxa. American Society of Horticulture Science Meeting, July 24-28, 2008, St. Louis, MO. meeting Prodeedings. 44(4):1007.
Upic: Perl Scripts to Determine the Number of Ssr Markers to Run - (Other)
Arias, R.S., Ballard, L.L., Scheffler, B.E. 2009. UPIC: Perl scripts to determine the number of SSR markers to run. Molecular markers in Horticulture Symposium, July 29-31, 2009, Corvallis, Oregon State University. Meeting Proceedings.
Bioengineering resistance to phytoene desaturase inhibitors in Arabidopsis thaliana - (Abstract Only)
Arias, R.S., Netherland, M.D., Michel, A., Duke, S.O., Scheffler, B.E., Dayan, F.E. 2004. Bioengineering resistance to phytoene desaturase inhibitors in Arabidopsis thaliana. Weed Science Society of America (WSSA) Meeting, February 11, 2004, Kansas City, MO. Meeting Proceedings.
|Food Safety Categories:||On-Farm Food Safety|
Plant Science & Plant Products
|Farm-to-Table Categories:||On-farm food production|
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