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THERE are many factors playing major role in use efficiency of phosphatic fertilizers, which varies from soil to another. Therefore, this study aims mainly to evaluate the effect of some trails, i.e. compost additives and P application times in different methods in sandy soil as well as its effect on growth, productivity and quality of peanut (Arachis hypogaea L.). This study was carried out as field experiment in sandy soil at South Al-Tahrir Sector, Al-Behaira Governorate, Egypt during two successive growing summer seasons. The experiment was laid out in a split plot design with three replicates. Four rates of compost i.e. (C1) 0, (C2) 4.76 (C3) 9.52 and (C4) 14.28 ton ha-1 were arranged in the main plots, while the four treatments of phosphorus were randomly distributed in the sub plots. With all the studied treatments of compost and P, the studied growth parameters, i.e. plant height (cm), number of branches per plant, and dry matter weights of straw and leaves were higher in the second growth season than those of first one. Data obtained from our experiments showed that growth parameters increased significantly with the increasing rates of compost application as well as with P applications in three doses (P4). Foliar application of P at 70-80 days of planting (P3) resulted in more increases in the determined growth parameters than those found with other treatments. Similar effect was found with peanut yields of pods and seeds and seeds contents of N, P and K as well as its content of protein and oil. [ABSTRACT FROM AUTHOR]

The bacterium, Streptomyces yanglinensis 3-10, shows promise in the control of many phytopathogenic fungi. In this study, S. yanglinensis and its antifungal substances, culture filtrate (CF3-10) and crude extracts (CE3-10), were evaluated for their activity in reducing growth and aflatoxin AFB1 production by Aspergillus flavus, both in vitro and in vivo on peanut kernels. The results showed that in dual culture conditions, S. yanglinensis reduced the mycelial growth of A. flavus about 41% as compared to control. The mycelial growth of A. flavus was completely inhibited on potato dextrose agar amended with CF3-10 at 3% (v/v) or CE3-10 at 2.5 mg/ml. In liquid culture experiments, growth inhibition ranged from 32.3 to 91.9% with reduction in AFB1 production ranging from 46.4 to 93.4% using different concentrations of CF3-10 or CE3-10. For in vivo assays, CF3-10 at 0.133 ml/g (v/w) or CE3-10 at 13.3 mg/g (w/w) reduced the postharvest decay of peanut kernels by inhibiting visible growth of A. flavus leading to an 89.4 or 88.1% reduction in AFB1 detected, respectively. Compared with the controls, CF3-10 and CE3-10 in A. flavus shake culture significantly reduced expression levels of two AFB1 biosynthesis genes, aflR and aflS. Furthermore, electron microscopy observation showed that CF3-10 (2%, v/v) caused hyphae growth to be abnormal and shriveled, cell organelles to degenerate and collapse, large vacuoles to appear. These results suggest that S. yanglinensis 3-10 has potential as an alternative to chemical fungicides in protecting peanut kernels and other agricultural commodities against postharvest decay from A. flavus. [ABSTRACT FROM AUTHOR]

The screening test of thirteen ground nut cultivars were conducted to study their resistance and susceptibility to Caryedon serratus in the laboratory at 70% RH and 28 ± 1°C. The successful development of adult beetles widely varied from 0.0 to 29.0 after one month. The variety OG 52-1 proved to be immune to the attack up to one month of storage. Percentage of weight loss due to beetle infestation was varied from 1.2 to 17.8% in first month of storage. The cultivar OG 52-1 recorded least weight loss. [ABSTRACT FROM AUTHOR]

Peanut stripe virus (PStV) belongs to the genus Potyvirus and is the most important viral pathogen of cultivated peanut (Arachis hypogaea L.). The eukaryotic translation initiation factor, eIF4E, and its isoform, eIF(iso)4E, play key roles during virus infection in plants, particularly Potyvirus. In the present study, we cloned the eIF4E and eIF(iso)4E homologs in peanut and named these as PeaeIF4E and PeaeIF(iso)4E, respectively. Quantitative real-time PCR (qRT-PCR) analysis showed that these two genes were expressed during all growth periods and in all peanut organs, but were especially abundant in young leaves and roots. These also had similar expression levels. Yeast two-hybrid analysis showed that PStV multifunctional helper component proteinase (HC-Pro) and viral protein genome-linked (VPg) both interacted with PeaeIF4E and PeaeIF(iso)4E. Bimolecular fluorescence complementation assay showed that there was an interaction between HC-Pro and PeaeIF4E/PeaeIF(iso)4E in the cytoplasm and between VPg and PeaeIF4E/PeaeIF(iso)4E in the nucleus. Silencing either PeaeIF4E or PeaeIF(iso)4E using a virus-induced gene silencing system did not significantly affect PStV accumulation. However, silencing both PeaeIF4E and PeaeIF(iso)4E genes significantly weakened PStV accumulation. The findings of the present study suggest that PeaeIF4E and PeaeIF(iso)4E play important roles in the PStV infection cycle and may potentially contribute to PStV resistance. [ABSTRACT FROM AUTHOR]

Late leaf spot (LLS) cause substantial yield losses and reduce the fodder and seed quality in groundnut (Arachis hypogaea L.). Knowledge on components of resistance to these diseases should facilitate the development of groundnut cultivars with enhanced resistance to LLS. The present investigation was performed to study the biochemical characterization of late leaf spot resistant groundnut genotypes viz., RHRG 6083, GPBD 4, KDG 128, ICG 11426, ICG 12672, ICG 13919, ICG 14475, ICGV 94118, ICGV 13160, ICGV 13165 including two wild species ICGV 13160 (Arachis batizocoi) and ICGV 13165 (A. cardenasi) and two susceptible viz., SB XI and JL 24 at AICRP on groundnut, MPKV, Rahuri during 2013-14 and 2014-15. The content of phenol and the enzyme activity of peroxidase and polyphenol oxidase was found more in resistant than susceptible genotypes, while total sugar content was found to be maximum in susceptible than resistant genotypes. There was reduction in reducing sugar content, while total sugar and total phenol and the enzyme activity of peroxidase and polyphenol oxidase was increased after inoculation of the pathogen in all groundnut genotypes. The reduction level of these biochemical constituents was less in resistant genotypes. Similarly, increased level of total sugar, total phenol, and peroxidase and polyphenol oxidase activity was more in resistant genotypes than susceptible genotypes. [ABSTRACT FROM AUTHOR]

Strong host resistance to root-knot nematode (RKN; Meloidogyne arenaria) introgressed from a wild diploid species to cultivated peanut was previously shown to be located on a large chromosomal region of linkage group A09. Little to no recombination in mapping populations has hindered fine mapping of the resistance genes. In order to further delineate the introgressed region, additional polymorphic markers were added to the linkage group A09 using a recombinant inbred line population developed from Gregory x Tifguard in which Gregory is the susceptible parent and Tifguard is the resistant parent harboring the alien introgression. Map distance within the introgressed region based on this population increased to 8 cM compared with zero recombination in an earlier generation. Lines with rare recombination within this introgressed region were phenotyped and it was demonstrated that one portion of the introgressed region confers moderate resistance while a smaller, distal portion confers strong resistance to RKN. Molecular markers associated with the introgressed region conferring strong resistance can be deployed in peanut breeding programs to improve selection for RKN resistance. [ABSTRACT FROM AUTHOR]

Introgression lines ( ILs) of groundnut with enhanced resistance to rust and late leaf spot ( LLS) recorded increased pod and haulm yield in multilocation testing. Marker-assisted backcrossing ( MABC) approach was used to introgress a genomic region containing a major QTL that explains >80% of phenotypic variance ( PV) for rust resistance and 67.98% PV for LLS resistance. ILs in the genetic background of TAG 24, ICGV 91114 and JL 24 were evaluated for two seasons to select 20 best ILs based on resistance, productivity parameters and maturity duration. Multilocation evaluation of the selected ILs was conducted in three locations including disease hot spots. Background genotype, environment and genotype × environment interactions are important for expression of resistance governed by the QTL region. Six best ILs namely ICGV 13192, ICGV 13193, ICGV 13200, ICGV 13206, ICGV 13228 and ICGV 13229 were selected with 39-79% higher mean pod yield and 25-89% higher mean haulm yield over their respective recurrent parents. Pod yield increase was contributed by increase in seed mass and number of pods per plant. [ABSTRACT FROM AUTHOR]

Aspergillus parasiticus is one of the most common fungi which contaminates peanuts by destroying peanut shells before they are harvested and the fungus produces aflatoxins. The aim of this study was to evaluate the antifungal activities of seventeen essential oils on the growth of the aflatoxigenic form of A. parasiticus in contaminated peanuts from commercial outlets in Georgia. The agar dilution method was used to test the antifungal activity of essential oils against this form of A. parasiticus at various concentrations: 500; 1,000; 1,500; 2,000; 2,500 ppm. Among the seventeen essential oils tested, the antifungal effect of cinnamon, lemongrass, clove and thyme resulted in complete inhibition of mycelial growth. Cinnamon oil inhibited mycelial growth at ≥ 1,000 ppm, lemongrass and clove oils at ≥ 1,500 ppm and thyme at 2,500 ppm. However, cedar wood, citronella, cumin and peppermint oils showed partial inhibition of mycelial growth. Eucalyptus oil, on the other hand, had less antifungal properties against growth of A. parasiticus, irrespective of its concentration. Our results indicate that the aflatoxigenic form of A. parasiticus is sensitive to selected essential oils, especially cinnamon. These findings clearly indicate that essential oils may find a practical application in controlling the growth of A. parasiticus in stored peanuts. [ABSTRACT FROM AUTHOR]

Background: Aflatoxin contamination caused by Aspergillus flavus in peanut (Arachis hypogaea) including in pre- and post-harvest stages seriously affects industry development and human health. Even though resistance to aflatoxin production in post-harvest peanut has been identified, its molecular mechanism has been poorly understood. To understand the mechanism of peanut response to aflatoxin production by A. flavus, RNA-seq was used for global transcriptome profiling of post-harvest seed of resistant (Zhonghua 6) and susceptible (Zhonghua 12) peanut genotypes under the fungus infection and aflatoxin production stress. Result: A total of 128.72 Gb of high-quality bases were generated and assembled into 128, 725 unigenes (average length 765 bp). About 62, 352 unigenes (48.43 %) were annotated in the NCBI non-redundant protein sequences, NCBI non-redundant nucleotide sequences, Swiss-Prot, KEGG Ortholog, Protein family, Gene Ontology, or eukaryotic Ortholog Groups database and more than 93 % of the unigenes were expressed in the samples. Among obtained 30, 143 differentially expressed unigenes (DEGs), 842 potential defense-related genes, including nucleotide binding site-leucine-rich repeat proteins, polygalacturonase inhibitor proteins, leucine-rich repeat receptor-like kinases, mitogen-activated protein kinase, transcription factors, ADP-ribosylation factors, pathogenesis-related proteins and crucial factors of other defense-related pathways, might contribute to peanut response to aflatoxin production. Notably, DEGs involved in phenylpropanoid-derived compounds biosynthetic pathway were induced to higher levels in the resistant genotype than in the susceptible one. Flavonoid, stilbenoid and phenylpropanoid biosynthesis pathways were enriched only in the resistant genotype. Conclusions: This study provided the first comprehensive analysis of transcriptome of post-harvest peanut seeds in response to aflatoxin production, and would contribute to better understanding of molecular interaction between peanut and A. flavus. The data generated in this study would be a valuable resource for genetic and genomic studies on crops resistance to aflatoxin contamination. [ABSTRACT FROM AUTHOR]

Stem rot of groundnut caused by Sclerotium rolfsii Sacc. is one of the major constraint to groundnut production in many countries. The fungus is ubiquitous, soil inhabitant and non-target. Screening of groundnut genotypes for resistance to stem rot under field conditions is complicated by the non-uniform spatial distribution of the pathogen. While development and maintenance of artificial sick plot with optimum inoculums load under field conditions are also difficult because of sensitivity of the pathogen to temperature, humidity, soil type, cropping system and host preference. In the present study, a screening technique under field conditions with high disease pressure has been reported. Twenty-five wild Arachis accessions and 178 F3 progenies along with two parents were screened under pot and field conditions, respectively for resistance to stem rot. Two wild Arachis accessions and three F3 lines were found resistant to stem rot with mortality less than 20% and 10%, respectively. [ABSTRACT FROM AUTHOR]

A marker assisted backcross breeding (MABC) programme was undertaken in an elite but foliar disease susceptible variety of groundnut, JL 24 for developing backcross lines using the donor, GPDB 4 by employing late leaf spot (LLS) and rust resistance-linked markers. Backcrossing and selfing resulted in the development of BC1F4, BC2F3 and BC3F3 generations. Evaluation of the backcross lines could identify JG4_81 and JG4_43 from BC1F4, and JG2-3_14 from BC2F3 as superior lines for disease resistance and productivity. A BC3F2 plant (JG_18) was homozygous at LLS and rust resistance-linked marker loci (IPAHM103, GM2301 and pPGPseq8D09) and 30 background markers loci. JG_18 had 87% background genome similarity with JL 24. When advanced to BC3F3, JG_18 showed resistance to both LLS and rust when compared to JL 24, while it was on par with JL 24 for the productivity traits. Currently, JG4_81, JG4_43, JG2-3_14 and JG_18 are under field evaluation for variety development. [ABSTRACT FROM AUTHOR]

Peanut (Arachis hypogaea L.) is one of the important oilseed crops of the Indian subcontinent and fungal diseases like early leaf spot (ELS) and late leaf spot (LLS) caused by Cercospora arachidicola and Phaeoisariopsis personata, respectively, are major peanut cultivation constraints. Defensins are basically antimicrobial peptides that have been implicated in plant defense against various microbial attacks. Transgenic peanut plants, developed through Agrobacterium mediated transformation of de-embryonated cotyledons and overexpressing a synthetic defensin fusion gene from fenugreek (Tfgd2) and radish (RsAFP2) linked by a linker peptide, were found to have enhanced resistance to the ELS and LLS infection over the wild type (cv. GG 20). Both transformed and untransformed lines were characterized for leaf spot diseases using a detached leaf assay. PCR and RT-PCR analyses confirmed stable integration and expression of these genes in peanut transgenics. This investigation provides further evidence that a fusion product of two plant defensins can be successfully implemented as a means of imparting resistance to multiple fungal pathogens through genetic engineering in peanut. [ABSTRACT FROM AUTHOR]

Peanut diseases, such as leaf spot and spotted wilt caused by Tomato Spotted Wilt Virus, can significantly reduce yield and quality. Application of marker assisted plant breeding requires the development and validation of different types of DNA molecular markers. Nearly 10,000 SSR-based molecular markers have been identified by various research groups around the world, but less than 14.5% showed polymorphism in peanut and only 6.4% have been mapped. Low levels of polymorphism limit the application of marker assisted selection (MAS) in peanut breeding programs. Insertion/deletion (InDel) markers have been reported to be more polymorphic than SSRs in some crops. The goals of this study were to identify novel InDel markers and to evaluate the potential use in peanut breeding. Forty-eight InDel markers were developed from conserved sequences of functional genes and tested in a diverse panel of 118 accessions covering six botanical types of cultivated peanut, of which 104 were from the U.S. mini-core. Results showed that 16 InDel markers were polymorphic with polymorphic information content (PIC) among InDels ranged from 0.017 to 0.660.With respect to botanical types, PICs varied from 0.176 for fastigiata var., 0.181 for hypogaea var., 0.306 for vulgaris var., 0.534 for aequatoriana var., 0.556 for peruviana var., to 0.660 for hirsuta var., implying that aequatoriana var., peruviana var., and hirsuta var. have higher genetic diversity than the other types and provide a basis for gene functional studies. Single marker analysis was conducted to associate specific marker to disease resistant traits. Five InDels from functional genes were identified to be significantly correlated to tomato spotted wilt virus (TSWV) infection and leaf spot, and these novel markers will be utilized to identify disease resistant genotype in breeding populations. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal (AM) fungi can play the potential role of bio-control agent, which will enable a putative perspective in bio-protection and intensive organic agricultural practices since chemical pesticides are associated with several health hazards. The objective of this pot culture research was to study the roles played by AM fungi (Glomus fasciculatum) in the biocontrol of pathogen Sclerotium rolfsii, which is a causal agent of stem-rot in groundnut plant. The experimental design was randomized complete block with four treatments and three replicates per treatment; data were analyzed with ANOVA and treatments means were compared using Tukey test (p⩽0.05). Groundnut plants were treated with AM S. rolfsii or both after 30, 60 and 90 d of planting. The soil based AM fungi were inoculated before pathogen inoculation. Results showed that S. rolfsii caused stem-rot disease in groundnut plants as expected, but the AM fungi inoculation significantly enhanced host plant endurance by decreasing stem-rot severity, and increased growth variables of inoculated plants. Besides, the effect of AM fungi was noticeable in root colonization and mycorrhizal dependency percentage, and there was a significant increase in content of total chlorophyll, protein, total phenols and polyphenol activities in mycorrhizal groundnut plants inoculated with pathogen. The antioxidant related response such as peroxidase was higher, reflecting a possible defense resistance mechanism induced upon by the AM fungi colonization by reducing the harmful effects of reactive oxygen species produced during the growth of groundnut plants due to S. rolfsii. [ABSTRACT FROM AUTHOR]

To clarify the phytoplasma associated with Huanglongbing (HLB), a detection survey of phytoplasma in field citrus trees was performed using the standardized nested PCR assay with primer set P1/16S-Sr and R16F2n/R16R2. The HLB-diseased citrus trees with typical HLB symptoms showed a high detection of 89.7% (322/359) of HLB-Las, while a low detection of phytoplasma at 1.1% (4/359) was examined in an HLB-affected Wentan pummelo (Citrus grandis) tree (1/63) and Tahiti lime (C. latifolia) trees (3/53) that were co-infected with HLB-Las. The phytoplasma alone was also detected in a healthy Wentan pummelo tree (1/60) at a low incidence total of 0.3% (1/347). Healthy citrus plants were inoculated with the citrus phytoplasma (WP-DL) by graft inoculation with phytoplasma-infected pummelo scions. Positive detections of phytoplasma were monitored only in the Wentan pummelo plant 4 months and 3.5 years after inoculation, and no symptoms developed. The citrus phytoplasma infected and persistently survived in a low titre and at a very uneven distribution in citrus plants. Peanut witches' broom (PnWB) phytoplasma (16SrII-A) and periwinkle leaf yellowing (PLY) phytoplasma belonging to the aster yellows group (16SrI-B) maintained in periwinkle plants were inoculated into healthy citrus plants by dodder transmission. The PnWB phytoplasma showed infection through positive detection of the nested PCR assay in citrus plants and persistently survived without symptom expression up to 4 years after inoculation. Positive detections of the phytoplasma were found in a low titre and several incidences in the other inoculated citrus plants including Ponkan mandarin, Liucheng sweet orange, Eureka lemon and Hirami lemon. None of the phytoplasma-infected citrus plants developed symptoms. Furthermore, artificial inoculation of PLY phytoplasma (16SrI-B) into the healthy citrus plants demonstrated no infection. The citrus symptomless phytoplasma was identified to belong to the PnWB phytoplasma group (16SrII-A). [ABSTRACT FROM AUTHOR]

Background and aim: Collar rot disease due to A. niger in ground nut plants causes a great loss in yield. Using a PGPR isolated from the field of same plants, we aimed to study effect on control of this disease as well as to study effect on seed germination and development of Induced systemic resistance in germinated seedlings. Methods: Different strain of bacteria were isolated and screened for their plant growth promoting activity. Selected bacterium was used for induction of systemic resistance in A. hypogaea L. against A. niger and identified using 16 s rRNA gene and FAME analysis. Results: A bacterium with plant growth promoting and antagonistic activity against A. niger was screened from the 25 bacteria isolated from the rhizospheric soil. It could reduce the incidence of collar rot disease by 66 % in plants. The bacterium could also induce systemic resistance in ground nut seedlings. Based on ez taxon BLAST results of its 16 s rRNA gene, biochemical tests for identification and FAME analysis, it was confirmed as a novel strain of Pseudomonas guariconensis (strain mungfali). Conclusion: A novel, agriculturally useful strain of P. guariconensis capable of controlling collar rot in A. hypogaea L., producing phytohormones and solubilizing N, P, K and Zn was found and named as strain mungfali . [ABSTRACT FROM AUTHOR]

Aspergillus flavus produces potent mutagenic and carcinogenic polyketidederived secondary metabolites known as aflatoxins. Development of host plant resistance in peanut and other crops is the most environmentally friendly and cost-effective method to eliminate the serious problem of aflatoxin contamination in grains. To confirm that putative peanut genes identified in a previous microarray study were involved in peanut resistance to A. flavus infection, 14 genes were selected for further investigation through real-time PCR. The results revealed diverse patterns of gene expression during seed germination after A. flavus inoculation. Based on the expression levels and the relative-expression patterns over a 7-day period, the 14 host genes could be classified into six different groups belonging to three main biochemical and genetic defence processes of lipid metabolism, oxidative signalling and cell-wall synthesis during counterattack. A network of gene expression patterns was activated in sequential order in response to A. flavus invasion in both resistant and susceptible peanut lines during seed germination. Understanding gene expression patterns in peanut will be useful to breeders and other scientists interested in incorporating genetic resources of resistance against A. flavus into peanut germplasm and/or commercial cultivars via conventional and/or molecular methods. [ABSTRACT FROM AUTHOR]

We have identified a transcript derived fragment (TDF) corresponding to SGT1 in a study of differential gene expression on the resistant wild peanut, Arachis diogoi, upon challenge from the late leaf spot pathogen, Phaeoisariopsis personata, and cloned its full-length cDNA followed by subsequent validation through q-PCR. Sodium nitroprusside, salicylic acid, ethephon and methyl jasmonate induced the expression of AdSGT1, while the treatment with abscisic acid did not elicit its up-regulation. AdSGT1 is localized to both nucleus and cytoplasm. Its overexpression induced hypersensitive-like cell death in tobacco under transient conditional expression using the estradiol system, and this conditional expression of AdSGT1 was also associated with the up-regulation of NtHSR203J, HMGR and HIN1, which have been shown to be associated with hypersensitive response in tobacco in earlier studies. Expression of the cDNA in a susceptible cultivated peanut variety enhanced its resistance against the late leaf spot pathogen, Phaeoisariopsis personata, while the heterologous expression in tobacco enhanced its resistance against Phytophthora parasitica var. nicotianae, Alternaria alternata var. nicotianae and Rhizoctonia solani. Constitutive expression in peanut was associated with the co-expression of resistance-related genes, CC-NB-LRR and some protein kinases. [ABSTRACT FROM AUTHOR]

A common set of 12 advanced Georgia peanut ( Arachis hypogaea L. subsp. hypogaea var. hypogaea) breeding lines that were derived from 'COAN' cross combinations were compared with three check cultivars for root-knot nematode (RKN) [ Meloidogyne arenaria (Neal) Chitwood race 1] resistance. These 15 genotypes were grown in RKN populated field tests using a randomized complete block design with three replications for two years (2011 and 2012). Two molecular markers (SCAR 197/909 and SSR-GM565) used for marker assisted selection (MAS) did not agree with low gall ratings and high pod yield for four out of the 15 genotypes (26.7%). The results were the same each year with the same four field RKN-resistant genotypes being incorrectly identified as susceptible (false negatives) by both markers. Reciprocal cross combinations involving field resistant parents showed one-gene difference between MAS resistant × MAS susceptible in F1 and F2 populations. The lack of accuracy differentiating resistant RKN breeding lines when using these two markers was attributed to either recombination between the resistant gene RMA and these two markers, or the possible identification of a second unlinked nematode resistant gene. Regardless, more tightly-linked molecular markers are needed for RKN-resistance in future MAS breeding programs. [ABSTRACT FROM AUTHOR]

A field investigation was carried out at Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University, during kharif 2009 and 2010 to evaluate the new formulation of imazethapyr (10% SL) on weed control in groundnut and its residual effect on succeeding crops. Based on two years field experimentation, it was found that early post emergence application of imazethapyr (10% SL) at 200 g ha-1 gave significantly lower total weed density, weed dry weight and higher weed control efficiency at all the stages. Application of new formulation of imazethapyr (10% SL) at 100 g ha-1 as early post emergence herbicide kept the weed density and dry weight below the economic threshold level and increased the pod yield (1602 and 1900 kg ha-1) and this was on par with 150 g ha-1 (1580 and 1854 kg ha-1) in groundnut. Succeeding crops like sunflower and pearl millet sown immediately after the harvest of groundnut was not affected by the residue of new formulation of imazethapyr at all different doses. [ABSTRACT FROM AUTHOR]

Numerous agrochemicals can be applied in peanut to control pests. Field and laboratory experiments were conducted in North Carolina during 2009 and 2010 to determine peanut response to paraquat and tobacco thrips ( Frankliniella fusca Hinds.) when acephate was applied in combination with chloroacetamide and contact herbicides. Experiments were also conducted during 2011 to determine peanut response to acephate applied alone or with paraquat when peanut was planted either without aldicarb or when aldicarb was applied in the seed furrow at planting. Visible peanut damage caused by tobacco thrips feeding was greater when chloroacetamide herbicides were applied without acephate compared with application with acephate regardless of paraquat treatment. Visible injury caused by paraquat was higher when chloroacetamide herbicides were included compared with paraquat alone in one of two years. Visible injury by paraquat was lower when applied with acephate compared to paraquat alone in one of two years. Acephate applied to peanut foliage and aldicarb applied in the seed furrow at planting protected peanut similarly from damage associated with tobacco thrips feeding. Acephate alone or with chloroacetamide herbicides changed solution pH from slightly acidic to highly acidic. Several combinations of pesticides formed either transient or permanent precipitates. [ABSTRACT FROM AUTHOR]

In 2003, 2004, and 2005 standard and reduced input fungicide programs were evaluated throughout the peanut production region of Georgia for control of early leaf spot ( Cercospora arachidicola), late leaf spot ( Cercosporidium personatum), and southern stem rot ( Sclerotium rolfsii). Disease risk was determined for each field based on the cultural practices implemented and ranged from low to high. Six to eight fungicide applications were made in the standard programs, versus three to six applications in reduced programs. Leaf spot ratings were higher for the reduced programs in five of the fourteen trials with substantial defoliation occurring in one trial. Overall, southern stem rot control for the reduced programs was equal to or better than that for the standard program, which could be attributed to the differences in fungicide selection or timing. Pod yields for the reduced programs were equal to or greater than the standard programs in all but one trial. Net returns were higher for the reduced programs in half of the trials; however, the reduced program resulted in lower net returns in one trial in 2004. Our results indicate that reduced input fungicide programs can be used to adequately manage fungal diseases of peanut without compromising yield or profitability, and that the use of cultivars with moderate levels of disease resistance may enhance disease control. [ABSTRACT FROM AUTHOR]

Wild Arachis species from section Arachis have been promoted as sources of resistance to common peanut diseases and insect pests. The objective of our study was to identify wild Arachis species with resistance to Sclerotinia blight and Cylindrocladium black rot (CBR). One hundred and ten accessions/entries from 23 Arachis species including A. hypogaea were evaluated in the greenhouses at North Carolina State University between January and March of 2010 in a 11×10 rectangular lattice experimental design with 4 replications for Sclerotinia blight and 6 replications for CBR. For the Sclerotinia blight test, seeds were planted in 10 cm clay pots and 8-wk-old plants were inoculated in a mist chamber with BEEM capsules containing the fungus inserted on the petioles of the 4th leaf from the apex on the primary branch. Lesion lengths were measured 4, 5, 6, and 7 d after inoculation, and areas under the disease progress curves (AUDPC) were calculated. For the CBR test, seeds were planted in soil mixed with microsclerotia (25/g) in cone-tainers partly immersed in water. Root damage was recorded after 60 d on a 0-5 proportional scale (0 = no decay to 5 = completely decayed). Data analysis indicated significant (p<0.05) variation among and within Arachis species for both diseases. Arachis glandulifera exhibited the highest level of Sclerotinia blight resistance followed by A. correntina, A. herzogii, and A. helodes, although the last three species were not significantly different from A. hypogaea. Overall, low genetic variability for Sclerotinia blight resistance was observed among the wild species accessions. For CBR, A. valida, A. cruziana, A. microsperma, A. williamsii, A. kempff-mercadoi, A. kuhlmannii, A. helodes, A. cardenasii and A. correntina formed the most resistant group with A. hypogaea in the most susceptible group. Overall, significant genetic variability for CBR resistance was found among the different wild species accessions. However, not all accessions within a species were resistant to either disease, and most accessions that were resistant to one disease were susceptible to the other. [ABSTRACT FROM AUTHOR]

‘Bowon' (Arachis Hypogaea L.) was developed at the National Crop Experiment Station (NCES) in Suwon during the period from 1991 to 2001 through the cross between a short stem with a few vegetative branches line SP8603 (Chibahandachi /Daekwangtangkong) and a large seeded with disease resistance variety ‘Daewontangkong'. This variety is belong to a Spanish type and complete erect type with a few branches, short stems and the habit of pod set clustered near the base of plant, which are more adaptable for dense planting and mechanized farming, and early maturing variety. Each pod contains two kernels with fleshy testa color and average weight of 100 kernels was 98 g, which was 19 g higher than that of check variety ‘Daekwangtangkong'. This variety showed higher degree in the lodging resistance and disease resistance against early and late leaf spot, and web blotch than those of check variety. This variety was found to be significantly higher in kernel yield per hectare by 17% over check variety and showing high yield stability from different year and location. [ABSTRACT FROM AUTHOR]

Abstract: Yield trials without fungicides or insecticides were conducted four consecutive years (2007–10) at the University of Georgia, Coastal Plain Experiment Station, Tifton Campus to evaluate for peanut (Arachis hypogaea L.) pest resistance. The most endemic diseases in the southeast U.S. are tomato spotted wilt (TSW) caused by Tomato spotted wilt virus, white mold (WM) caused by Sclerotium rolfsii Sacc, and both early and late leaf spot caused by Cercospora arachidicola Hori and Cercosporidium personatum (Berk & Curt.) Deighton, respectively. The most endemic insects are tobacco thrips (Frankliniella fusca Hinds) and potato leafhopper (Empoasca fabae Harris). Results from these replicated field tests showed significant differences (P ≤ 0.05) among advanced Georgia breeding lines and cultivars. Three Georgia cultivars ‘Georgia-01R’, ‘Georgia-05E’, and ‘Georgia-10T’ consistently produced among the best yields with high levels of resistance to TSW, white mold, leafhoppers, and leaf spot each year. Georgia-01R is a multiple-pest-resistant, runner-type cultivar with late maturity; whereas, Georgia-05E is a multiple-pest-resistant, virginia-type cultivar with medium-late maturity. Georgia-10T is a new runner-type cultivar with high level of TSWV and white mold resistance and late-maturity, similar to Georgia-01R, one of its parents. However, Georgia-10T does not appear to have the high level of leaf spot and leafhopper resistance as Georgia-01R, but it still had high yields in the absence of fungicides or insecticides. [Copyright &y& Elsevier]

The antagonistic effect of a native isolate of Trichoderma spp., was evaluated for Sclerotium rolfsii Sacc. control, under in vitro and glasshouse conditions, at the North Region of Guerrero State. Twelve Trichoderma spp. native isolates were obtained (2 from Santa Teresa and 10 from Tlaxmalac, Gro), of which six were selected (Tcn-4, Tcn-5, Tcn-6, Tcn-7, Tcn-8 and Tcn-11) by the cellophane paper method. Under in vitro conditions, the percentage of inhibition varied from 10.0 to 94.4%; it was registered using the paired cultures technique, antagonism class two with isolate Tcn-11, in these conditions the growth of the plant pathogen was inhibited and decreased its development over the 80% of the medium culture surface in the Petri box. The native strain Tcn-11 morphologically and genetically identified as T. harzianum Rifai was evaluated under glasshouse conditions and compared with a strain collection (Thzcf-12) and a commercial fungicide at three inoculation times. The plant pathogen S. rolfsii was not sufficiently aggressive to cause death of the peanut plant; however, negative effects were observed on plant development and seed production. The strains Tcn-11 and Thzcf-12 were able to contribute to the development of the peanut plant and to help protect it from infection of S. rolfsii in a more efficient way than the fungicidal pentacloronitrobenzene (PCNB). [ABSTRACT FROM AUTHOR]

In order to utilize germplasm resources more efficiently for peanut (Arachis hypogaea L.) genetic improvement, a core collection of 576 accessions and a primary mini core collection of 298 accessions were developed previously from a collection of 6839 cultivated peanut lines stored at the Oil Crops Research Institute of Chinese Academy of Agricultural Sciences at Wuhan. For an efficient evaluation and characterization of the most useful agronomic and disease-resistant traits, an even smaller collection of peanut accessions that represent a spectrum of phenotypes could be more desirable. For this reason, a mini-mini core collection with 99 accessions from the core accessions was developed based on the analysis of 21 morphological traits. It was demonstrated that there were no significant differences between the core and mini-mini core collections in 20 out of the 21 morphological traits studied. Further, the mini-mini core collection captured the ranges of all of the 21 traits displayed in the core collection. The newly developed mini-mini core collection was assessed for resistance to bacterial wilt disease caused by Ralstonia solanacearum. Two accessions showing a high level of resistance to bacterial wilt were identified, demonstrating the usefulness of the mini-mini core collection. The mini-mini-core collection provides a more efficient means of germplasm evaluation and will be resequenced as part of the International Peanut Genome Consortium sequencing project at the UC-Davis Genome Center. [ABSTRACT FROM AUTHOR]

Abstract: This work aims to establish characteristic SDS-PAGE profiles of peanut seed albumins and prolamins associated with Aspergillus flavus resistance assay. Comparing to the traditional method, a successful alternate method was developed by sequential extraction with 2M NaCl in buffer (pH 6.8), 70% ethanol and w ter. The alcohol-soluble prolamin fraction from the present method showed unique profiles possessing antifungal activity against spore germination and mycelial growth. The water-soluble albumin fraction had specific profiles and demonstrated inhibition only on mycelial growth. Yet, the salt-soluble globulin fraction enhanced both processes of A. flavus propagation. [Copyright &y& Elsevier]

Late leaf spot (LLS) and rust have the greatest impact on yield losses worldwide in groundnut ( Arachis hypogaea L.). With the objective of identifying tightly linked markers to these diseases, a total of 3,097 simple sequence repeats (SSRs) were screened on the parents of two recombinant inbred line (RIL) populations, namely TAG 24 × GPBD 4 (RIL-4) and TG 26 × GPBD 4 (RIL-5), and segregation data were obtained for 209 marker loci for each of the mapping populations. Linkage map analysis of the 209 loci resulted in the mapping of 188 and 181 loci in RIL-4 and RIL-5 respectively. Using 143 markers common to the two maps, a consensus map with 225 SSR loci and total map distance of 1,152.9 cM was developed. Comprehensive quantitative trait locus (QTL) analysis detected a total of 28 QTL for LLS and 15 QTL for rust. A major QTL for LLS, namely QTL01 (GM1573/GM1009-pPGPseq8D09), with 10.27-62.34% phenotypic variance explained (PVE) was detected in all the six environments in the RIL-4 population. In the case of rust resistance, in addition to marker IPAHM103 identified earlier, four new markers (GM2009, GM1536, GM2301 and GM2079) showed significant association with the major QTL (82.96% PVE). Localization of 42 QTL for LLS and rust on the consensus map identified two candidate genomic regions conferring resistance to LLS and rust. One region present on linkage group AhXV contained three QTL each for LLS (up to 67.98% PVE) and rust (up to 82.96% PVE). The second candidate genomic region contained the major QTL with up to 62.34% PVE for LLS. Molecular markers associated with the major QTL for resistance to LLS and rust can be deployed in molecular breeding for developing groundnut varieties with enhanced resistance to foliar diseases. [ABSTRACT FROM AUTHOR]

Three varieties of Arachis hypogeae, GG 11, GG 20 and GG 24, were compared for resistance against A. niger. GG 20 showed the least disease severity. Infection with A. niger resulted in a rapid increase in NADPH oxidase, Glutathione reductase (GR) and salicylic acid in all the three varieties, indicating hyper increase of reactive oxygen species (ROS) and activation of phenyl propanoid pathway. Ferric reducing antioxidant power value was found to be decreasing due to infection in all the three varieties, confirming the role of ROS in pathogenesis. Since A. niger was found to cause pathogenesis by oxidative stress, the treatment of zinc was given as an antioxidant and its effect was studied. The application of zinc inhibited NADPH oxidase and GR activity in the control as well as in the infected GG 11 and GG 24 varieties but induced in the tolerant variety GG 20. Because zinc treatment could control the ROS in GG 11 and GG 24 varieties, disease severity was reduced but in GG 20 variety, zinc treatment aggravated ROS levels and also the disease severity. The protein profile of GG 20 in comparison to GG 11 and GG 24 varieties revealed one oligomeric protein of 110 kD as one of the responsible factors for its resistance. Total oil and its iodine value were found little higher in GG 20 variety than in other two varieties. It was found that the control of ROS could control the A. niger infection in Arachis hypogeae. [ABSTRACT FROM PUBLISHER]

Abstract: Field studies were conducted from 2006 to 2008 in the peanut (Arachis hypogaea) growing regions of Georgia, North Carolina, and Texas to ascertain two formulations of imazapic marketed as formulation-1 (Cadre®) and formulation-2 (Impose®). Both formulations controlled Acanthospermum hispidum, Eclipta prostrate, Richardia scabra, Verbesina encelioides, Amaranthus palmeri, Ipomoea lacunosa, Sida spinosa, Cucumis melo, Urochloa texana, Cyperus rotundus, and Cyperus esculentus at least 70% in most instances. Ambrosia artemisiifolia and Trianthema portulacastrum control was poor (>70%). Neither formulation of imazapic alone injured peanut in south Texas; however, in Georgia peanut injury ranged from 3 to 8% and in North Carolina injury was 8–20% when rated up to 27d after herbicide application. Imazapic, regardless of formulation, applied with bentazon injured peanut 5–20% in Georgia and North Carolina but not in Texas. Either formulation of imazapic plus paraquat injured peanut 15–30% in Georgia, 8–17% in Texas, and 28–48% in North Carolina. Imazapic, regardless of formulation, in combination with paraquat reduced yield compared with imazapic alone at one of four locations. [Copyright &y& Elsevier]

A lactose-specific lectin (named Arachis hypogaea L Lectin (AHL)) was purified from the seed of the peanut Arachis hypogaea L. by single-step affinity chromatography using lactose-coupled agarose. AHL showed strong hemagglutinating activity to human A/B/O erythrocytes (RBC) treated with neuraminidase. The results of matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry (MALDI-TOF-TOF MS) analysis indicated that the protein AHL shared high homology with the peanut lectin chain A protein (gi|1942899). The AHL has binding activity to some Gram-negative bacteria and fungi spores which caused disease in peanut. Transcripts of AHL were detected in different peanut tissues, and the expression profile of the AHL gene changed in different parts of the plants. The variation in the mRNA transcript level in seeds was quantitated by real-time polymerase chain reaction during different growth periods. The expression profile of the AHL gene changed greatly in samples collected in different days after pegging. We explored the variation in AHL mRNA expression in six cultivars of peanut; the expression level observed in Lu Hua 12 was the highest. The data we described can provide us with clues to know more properties about peanut seed lectins at the biology chemistry and molecular biology level. [ABSTRACT FROM AUTHOR]

Background: Aflatoxin contamination caused by Aspergillus flavus is a major constraint to peanut industry worldwide due to its toxicological effects to human and animals. Developing peanut varieties with resistance to seed infection and/or aflatoxin accumulation is the most effective and economic strategy for reducing aflatoxin risk in food chain. Breeding for resistance to aflatoxin in peanut is a challenging task for breeders because the genetic basis is still poorly understood. To identify the quantitative trait loci (QTLs) for resistance to aflatoxin contamination in peanut, a recombinant inbred line (RIL) population was developed from crossing Zhonghua 10 (susceptible) with ICG 12625 (resistant). The percent seed infection index (PSII), the contents of aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) of RILs were evaluated by a laboratory kernel inoculation assay. Results: Two QTLs were identified for PSII including one major QTL with 11.32–13.00% phenotypic variance explained (PVE). A total of 12 QTLs for aflatoxin accumulation were detected by unconditional analysis, and four of them (qAFB1A07 and qAFB1B06.1 for AFB1, qAFB2A07 and qAFB2B06 for AFB2) exhibited major and stable effects across multiple environments with 9.32–21.02% PVE. Furthermore, not only qAFB1A07 and qAFB2A07 were co-localized in the same genetic interval on LG A07, but qAFB1B06.1 was also co-localized with qAFB2B06 on LG B06. Conditional QTL mapping also confirmed that there was a strong interaction between resistance to AFB1 and AFB2 accumulation. Genotyping of RILs revealed that qAFB1A07 and qAFB1B06.1 interacted additively to improve the resistance to both AFB1 and AFB2 accumulation. Additionally, validation of the two markers was performed in diversified germplasm collection and four accessions with resistance to aflatoxin accumulation were identified. Conclusions: Single major QTL for resistance to PSII and two important co-localized intervals associated with major QTLs for resistance to AFB1 and AFB2. Combination of these intervals could improve the resistance to aflatoxin accumulation in peanut. SSR markers linked to these intervals were identified and validated. The identified QTLs and associated markers exhibit potential to be applied in improvement of resistance to aflatoxin contamination. [ABSTRACT FROM AUTHOR]