Search

Phytophagous insects utilize visual, olfactory and gustatory cues to find food. The brown marmorated stink bug, Halyomorpha halys (Stål), quickly approaches fresh peanut seeds newly introduced into the rearing cage in the laboratory but shows less interest in stale peanut seed previously infested by conspecifics. This observation suggests that H. halys can perceive the quality of food by detecting the volatile(s) from fresh peanut seeds. A bioassay revealed that H. halys adults could more quickly find fresh peanut seeds than three-day-infested peanut seeds, which is consistent with laboratory observations. Hexanal was found to be the major volatile component of fresh peanut seeds but not of previously infested ones. In the two-choice assays, the adult bugs that did respond were significantly attracted to fresh peanut volatiles and hexanal. Hexanal also induced proboscis-protruding behavior in adult H. halys, which suggested that this compound is a key stimulant of foraging behavior of laboratory-reared H. halys adults. © Pesticide Science Society of Japan. [ABSTRACT FROM AUTHOR]

Peanuts (Arachis hypogaea L.) can be attacked by many pathogens both in field and in deposits. Most of the time the peanuts are healthy, but during improper storage they can be contaminated with fungi. The myco-flora associated with the peanut seeds is formed mainly by fungi from the genera Aspergillus, Fusarium, Penicillium and Rhizopus. The mentioned fungi are very harmful for health because they are producing carcinogenic mycotoxins. Mainly the Aspergillus species can infect peanuts during the vegetation period, especially in the case very high humidity conditions in field. Thus, the infection can continue during the harvesting, transport and storage. Due to this fact, the problem of the accumulation of aflatoxins is very serious in the big peanut cultivating countries. Many researches show the presence of the aflatoxins in the sold peanuts. The approached topic in this research is actually and presents interests for the consumers in special. The identification if the myco - toxigenous from peanuts from supermarket was realised on seeds that were originating from four countries (Romania, Brasil, U. S. A. and Egypt). The main objective of this laboratory study was to identify the myco - toxigenous fungi, mainly those that grow on and from peanuts sold in supermarkets in Timisoara. During the sample collection there was considered the origin of the peanuts to comprise different parts of the world. The peanuts were bought from big supermarkets. The obtained results regarding the fungal contamination index of the peanuts seeds with fungi show the presence in myco - flora of some myco - toxigenous fungi harmful for health. Fusarium sp. is highlighted in all the samples by a quite great contamination rate comprised between 5.12% (the peanut crust samples from U. S. A.). The contamination of the seeds with the myco-toxigenous fungus Aspergillus flavus is obvious in the case of the peanuts from U. S. A. where was registered the greatest infection rate of 25.89% in seeds and 10.25% in crusts. The third fungus that was determined in quite great rates on the peanuts seeds was Penicillium sp. The greatest infection level was registered in the samples from China (24.56%) and U. S. A. (22.32%). Aside the three myco - toxigenous fungi was grown in a great rate in some samples the fungus Rhizopus sp., that usually is present in the peanuts seeds. The greatest infection level of the infection was determined in the peanuts from Egypt (65.85%) and those from Romania (64.56%). [ABSTRACT FROM AUTHOR]

Aflatoxins are among the most powerful carcinogens in nature. The major aflatoxin-producing fungi areAspergillus flavusandA. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow that allowed prescreening of 238AspergillussectionFlaviisolates from peanut seeds from Georgia, USA. The aflatoxin biosynthesis cluster (ABC) of the isolates was fingerprinted at 25 InDel (insertion/deletion) loci using capillary electrophoresis. All isolates were tested for aflatoxins using ultra-high-performance liquid chromatography. The neighbor-joining, three-dimension (3D) principal coordinate, and Structure analyses revealed that theAspergillusisolates sampled consisted of three main groups determined by their capability to produce aflatoxins. Group I comprised 10 non-aflatoxigenicA. flavus; Group II includedA. parasiticus; and Group III included mostly aflatoxigenicA. flavusand the three non-aflatoxigenicA. caelatus. Whole genomes of 10 representative isolates from different groups were sequenced. Although InDels inAspergillushave been used by other research groups, this is the first time that the cluster analysis resulting from fingerprinting was followed by whole-genome sequencing of representative isolates. In our study, cluster analysis of ABC sequences validated the results obtained with fingerprinting. This shows that InDels used here can predict similarities at the genome level. Our results also revealed a relationship between groups and their capability to produce aflatoxins. The database generated ofAspergillusspp. can be used to select target genes and assess the effectiveness of RNAi technology to reduce aflatoxin contamination in peanut. [ABSTRACT FROM AUTHOR]

Peanut, an important oil producing crop contains bioactive compounds like phenolics and flavonoids which determine its antioxidative activity. We report here the genetic variability for total phenolics, flavonoids and DPPH radical scavenging activity of testaless seeds of a peanut recombinant inbred line population. On an average, the population contained 1.65 mg GAE/g and 240 µg CE/g of phenolics and flavonoids, respectively in its seed. The DPPH radical scavenging activity of this population ranged from 1.27 to 4.40 mM of TEAC/g of seed with an average of 2.87 mM of TEAC/g and had significant positive correlation with both phenolics and flavonoids content. Genetic mapping and QTL analysis revealed five QTLs for total flavonoid content, four QTLs for DPPH radical scavenging activity and a single QTL for total phenolic content in six linkage groups. Of these 10 QTLs, six were positioned in linkage group A02 and A03 wherein rust and late leaf spot resistance genes were located. [ABSTRACT FROM AUTHOR]

Copyright of Revista Agro@mbiente On-line is the property of Revista Agro@mbiente On-line and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background and Aims: The role and linkage of endophytic bacteria to resistance of peanut seeds to biotic stress is poorly understood. The aims of the present study were to survey the experimental (axenic) and control (conventional) peanut plants for the predominant endophytic bacteria, and to characterize isolates with activity against selected A. flavus strains. Methods: Young axenic plants were grown from presumably bacteria-free embryos in the lab, and then they were grown in a field. Endophytic bacterial species were identified by the analysis of DNA sequences of their 16S-ribosomal RNA gene. DNA extracted from soil was also analyzed for predominant bacteria. Results: Mature seeds from the experimental and control plants contained several species of nonpathogenic endophytic bacteria. Among the eight bacterial species isolated from seeds, and DNA sequences detected in soil, Bacillus thuringiensis was dominant. All B. amyloliquefaciens isolates, the second abundant species in seeds demonstrated activity against A. flavus. This effect was not observed with any other bacterial isolates. There was no significant difference in number and relative occurrence of the two major bacterial species between the experimental and conventionally grown control seeds. Conclusion: Endophytic bacterial colonization derives from local soil and not from the seed source, and the peanut plant accommodates only selected species of bacteria from diverse soil populations. Some bacterial isolates showed antibiosis against A. flavus. [ABSTRACT FROM AUTHOR]

Abstract: Two new stilbene dimers (arahypin-8 and arahypin-9) and one monomeric stilbene derivative arahypin-10 were isolated for the first time from wounded peanut seeds challenged by a Rhizopus oligoporus strain, a starter culture for soybean fermentation in Southeast Asia. The structures of the three new compounds were elucidated on the basis of HRESIMS, UV, 1D and 2D NMR spectroscopy and the plausible mechanism of their formation was proposed. In addition, these compounds showed insulin sensitizing effect by enhancing insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes. [Copyright &y& Elsevier]