Dawson, GA, United States
Dawson, GA, United States

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Koike S.T.,University of California Cooperative Extension | Arias R.S.,National Peanut Research Laboratory | Hogan C.S.,U.S. Department of Agriculture | Martin F.N.,U.S. Department of Agriculture | Gordon T.R.,University of California at Davis
International Journal of Fruit Science | Year: 2016

Macrophomina crown and root rot has become a significant soil-borne disease issue in California. For many locations in the state, the disease is associated with fields that are no longer pre-plant, flat field fumigated with methyl bromide + chloropicrin. Inoculation experiments indicated that some differences in strawberry cultivar susceptibility to Macrophomina phaseolina were seen a short time after the inoculation, but as disease progressed such differences did not persist. Preliminary characterization studies of Macrophomina phaseolina isolates from strawberry indicated that such isolates may have a host preference for strawberry. Macrophomina phaseolina isolates from watermelon, thyme, and apple failed to cause disease in strawberry. Five cover crop species, which can be rotated with strawberry, did not develop disease when inoculated with strawberry isolates. In preliminary analysis using simple sequence repeat markers, isolates obtained from strawberry formed a separate group compared to isolates recovered from other known Macrophomina phaseolina hosts. © 2016 Taylor & Francis


Sundaram J.,National Peanut Research Laboratory | Kandala C.V.K.,National Peanut Research Laboratory | Butts C.L.,National Peanut Research Laboratory
Sensing and Instrumentation for Food Quality and Safety | Year: 2010

One of the grading factors for peanuts is their classification into peanuts with good or bad kernels. Traditional manual methods are labor intensive and subjective. A device by which the classification could be done rapidly and without the need to shell the peanuts would be very useful for the peanut industry. In this work VIS/NIR spectroscopy was used for this purpose. Reflectance spectra were collected for peanut pods (in-shell peanuts) in the wavelength range of 400-2500 nm. A calibration group of about 200 pods were initially scanned to train the classification algorithm. Each individual pod was shelled and the kernels were visually examined and classified as bad if they had any kind of damage, discoloration or immaturity. The remaining pods were marked as good ones. The Principal component analysis model generated from primary spectra with or without pretreatments gave explained variance better than 99%. The maximum normalization model with the ability of characterizing good and bad kernels with an accuracy of 80% and with low SEP and RMSEP values of 0. 43, would be useful in the quality characterization of in-shell peanuts. © 2010 US Government.


Yang T.,Arkansas State University | Fang L.,Arkansas State University | Rimando A.M.,U.S. Department of Agriculture | Sobolev V.,National Peanut Research Laboratory | And 2 more authors.
Plant Physiology | Year: 2016

Prenylated stilbenoids synthesized in some legumes exhibit plant pathogen defense properties and pharmacological activities with potential benefits to human health. Despite their importance, the biosynthetic pathways of these compounds remain to be elucidated. Peanut (Arachis hypogaea) hairy root cultures produce a diverse array of prenylated stilbenoids upon treatment with elicitors. Using metabolic inhibitors of the plastidic and cytosolic isoprenoid biosynthetic pathways, we demonstrated that the prenyl moiety on the prenylated stilbenoids derives from a plastidic pathway. We further characterized, to our knowledge for the first time, a membrane-bound stilbenoid-specific prenyltransferase activity from the microsomal fraction of peanut hairy roots. This microsomal fraction-derived resveratrol 4-dimethylallyl transferase utilizes 3,3-dimethylallyl pyrophosphate as a prenyl donor and prenylates resveratrol to form arachidin-2. It also prenylates pinosylvin to chiricanine A and piceatannol to arachidin-5, a prenylated stilbenoid identified, to our knowledge, for the first time in this study. This prenyltransferase exhibits strict substrate specificity for stilbenoids and does not prenylate flavanone, flavone, or isoflavone backbones, even though it shares several common features with flavonoid-specific prenyltransferases. © 2016 American Society of Plant Biologists. All Rights Reserved.


Devi J.M.,North Carolina State University | Rowland D.L.,University of Florida | Payton P.,U.S. Department of Agriculture | Faircloth W.,National Peanut Research Laboratory | Sinclair T.R.,North Carolina State University
Field Crops Research | Year: 2013

Peanut is often grown in the U.S. on sandy soil with limited water holding capacity. Since nitrogen fixation activity of other grain legume species, and some peanut cultivars, has been found to be especially sensitive to soil drying, yield improvement may be possible by identifying and/or breeding cultivars with nitrogen fixation resistance to water-deficit conditions. A key in this approach will be the use of screens to identify genotypes that may express drought resistance. Two screens of differing experimental sophistication were explored in this study as potential tools to compare genotypes. The first screen was done in the greenhouse using intact plants in a flow-though acetylene reduction system to measure nitrogen fixation response to soil drying over about two weeks. Ten commercial cultivars were tested and the only significant difference in nitrogen fixation activity was between Georgia 06G and York. The threshold for the decline in the nitrogen fixation rate averaged at a relative high value of 0.37 but Georgia 06G had a relatively low value of 0.28. These thresholds are greater than have been reported for nitrogen fixation tolerance in other species. The second, less sensitive screen that can be applied to a much larger number of genotypes was done in the field by measuring nitrogen accumulation over 2-3 wks of growth on limited available soil water. There were no differences in nitrogen-to-mass accumulation ratio among the commercial cultivars during two limited-water experiments. However, data collected from the field on several breeding lines from India indicated a consistency in the identification of nitrogen fixation in the greenhouse experiment and field experiments. © 2013 Elsevier B.V.


Dang P.M.,National Peanut Research Laboratory | Chen C.Y.,Auburn University | Holbrook C.C.,U.S. Department of Agriculture
Functional Plant Biology | Year: 2013

Drought can significantly limit yield and quality in peanut (Arachis hypogaea L.), depending on its timing, duration and severity. The objective of this study was to identify potential molecular mechanism(s) utilising a candidate-gene approach in five peanut genotypes with contrasting drought responses. An early season drought stress treatment was applied under environmentally controlled rain-out shelters. When water was completely withheld for 3 weeks, no physical differences were observed for treated plants compared with their fully irrigated counterparts as indicated by relative water content; however, yield, grades (total sound mature kernel, TSMK), specific leaf area, and leaf dry matter content showed significant differences. Comparing expression levels of candidate genes, 'C76-16' exhibited significantly higher levels for CuZnSOD, NsLTP and drought protein 1 week earlier compared to the other genotypes, followed by significantly lower levels for the same genes. This suggested an early recognition of drought in C76-16 followed by an acclimation response. Cultivar 'Georgia Green' showed different patterns of gene-expression than C76-16. AP-3, a susceptible genotype, showed generally lower levels of gene-expression than C76-16 and Georgia Green. Myo-inositol phosphate synthase gene-expression showed high levels in irrigated treatment, ranging from 4-fold for 08T-12 to 12-fold for Georgia Green, but were significantly inhibited in drought treatment after 2 weeks of drought and after recovery. © 2013 CSIRO.


PubMed | National Peanut Research Laboratory, The Broad Institute of MIT and Harvard, Valdosta State University, University of Georgia and U.S. Department of Agriculture
Type: Journal Article | Journal: Genome announcements | Year: 2015

Cercospora arachidicola, causal agent of early leaf spot, is an economically important peanut pathogen. Lack of genetic information about this fungus prevents understanding the role that potentially diverse genotypes may have in peanut breeding programs. Here, we report for the first time a draft genome sequence of C.arachidicola.


PubMed | University of Georgia, National Peanut Research Laboratory, Haramaya University and Hawassa University
Type: Journal Article | Journal: Food additives & contaminants. Part B, Surveillance | Year: 2016

This study was conducted to assess major Aspergillus species and aflatoxins associated with groundnut seeds and cake in Eastern Ethiopia and evaluate growers management practices. A total of 160 groundnut seed samples from farmers stores and 50 groundnut cake samples from cafe and restaurants were collected. Fungal isolation was done from groundnut seed samples. Aspergillus flavus was the dominant species followed by Aspergillus parasiticus. Aflatoxin analyses of groundnut seed samples were performed using ultra performance liquid chromatography; 22.5% and 41.3% of samples were positive, with total aflatoxin concentrations of 786 and 3135ngg


PubMed | National Peanut Research Laboratory
Type: | Journal: Journal of visualized experiments : JoVE | Year: 2015

The Food and Agriculture Organization of the United Nations estimates that 25% of the food crops in the world are contaminated with aflatoxins. That represents 100 million tons of food being destroyed or diverted to non-human consumption each year. Aflatoxins are powerful carcinogens normally accumulated by the fungi Aspergillus flavus and A. parasiticus in cereals, nuts, root crops and other agricultural products. Silencing of five aflatoxin-synthesis genes by RNA interference (RNAi) in peanut plants was used to control aflatoxin accumulation following inoculation with A. flavus. Previously, no method existed to analyze the effectiveness of RNAi in individual peanut transgenic events, as these usually produce few seeds, and traditional methods of large field experiments under aflatoxin-conducive conditions were not an option. In the field, the probability of finding naturally contaminated seeds is often 1/100 to 1/1,000. In addition, aflatoxin contamination is not uniformly distributed. Our method uses few seeds per transgenic event, with small pieces processed for real-time PCR (RT-PCR) or small RNA sequencing, and for analysis of aflatoxin accumulation by ultra-performance liquid chromatography (UPLC). RNAi-expressing peanut lines 288-72 and 288-74, showed up to 100% reduction (p 0.01) in aflatoxin B1 and B2 compared to the control that accumulated up to 14,000 ng g(-1) of aflatoxin B1 when inoculated with aflatoxigenic A. flavus. As reference, the maximum total of aflatoxins allowable for human consumption in the United States is 20 ng g(-1). This protocol describes the application of RNAi-mediated control of aflatoxins in transgenic peanut seeds and methods for its evaluation. We believe that its application in breeding of peanut and other crops will bring rapid advancement in this important area of science, medicine and human nutrition, and will significantly contribute to the international effort to control aflatoxins, and potentially other mycotoxins in major food crops.


PubMed | National Peanut Research Laboratory and U.S. Department of Agriculture
Type: Journal Article | Journal: Genome announcements | Year: 2016

Aspergillus flavusandA.parasiticusfungi produce carcinogenic mycotoxins in peanut seeds, causing considerable impact on both human health and the economy. Here, we report nine genome sequences ofAspergillusspp., isolated from Georgia peanut seeds in 2014. The information obtained will lead to further biodiversity studies that are essential for developing control strategies.


PubMed | National Peanut Research Laboratory
Type: Journal Article | Journal: Mycotoxin research | Year: 2013

The etiology of the classical turkey X disease syndrome is reappraised based on original reports in conjunction with current information. The clinical signs described in those original reports cannot be totally explained as being typical for aflatoxicosis. The unexplained effects of the disease can be resolved by the proposed presence of the mycotoxin cyclopiazonic acid which is frequently produced byAspergillus flavus along with the aflatoxins.

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