Draft genome sequence data of Nothopassalora personata, peanut foliar pathogen from Argentina

Late leaf spot (LLS) caused by the Ascomycete Nothopassalora personata (N.p.) (Syn. Cercosporidium personatum) is the main foliar disease of peanuts in Argentina and in peanut producing areas of the world, causing up to 70% yield losses. The extremely slow growth of this fungus in culture, that takes around one month to form a 1 cm colony (0.45 mm/day), and the lack of adequate young tissues from where to extract nucleic acids, have hindered genetic studies of this pathogen. Here, we report the first genome sequence of a N. personata isolate from South America, as well as genetic variants on its conserved genes, and the complete sequence of its mating-type locus MAT1-2 idiomorph. The N. personata isolate IPAVE 0302 was obtained from peanut leaves in Córdoba, Argentina. The whole genome sequencing of IPAVE 0302 was performed as paired end 150 bp NovaSeq 6000 and de novo assembled. Clean reads were mapped to the reference genome for this species NRRL 64463 and the genetic variants on highly conserved genes and throughout the genome were analyzed. Sequencing data were submitted to NCBI GenBank Bioproject PRJNA948451, accession number SRR23957761. Additional Fasta files are available from Harvard Dataverse (https://doi.org/10.7910/DVN/9AGPMG and https://doi.org/10.7910/DVN/YDO3V6). The data reported here will be the basis for the analysis of genetic diversity of the LLS pathogen of peanut in Argentina, information that is critical to make decisions on management strategies.

Limestone and yellow gypsum can reduce cadmium accumulation in groundnut (Arachis hypogaea): A study from a three-decade old landfill site

Cadmium (Cd) toxicity has cropped up as an important menace in the soil-plant system. The use of industrial by-products to immobilise Cd in situ in polluted soils is an interesting remediation strategy. In the current investigation, two immobilizing amendments of Cd viz., Limestone (traditionally used) and Yellow gypsum (industrial by-product) have been used through a green-house pot culture experiment. Soil samples were collected from four locations based on four graded levels of DTPA extractable Cd as Site 1 (0.43 mg kg-1), Site 2 (0.92 mg kg-1), Site 3 (1.77 mg kg-1) and Site 4 (4.48 mg kg-1). The experiment was laid out in a thrice replicated Factorial Complete Randomized Design, with one factor as limestone (0, 250, 500 mg kg-1) and the other being yellow gypsum (0, 250, 500 mg kg-1) on the collected soils and groundnut was grown as a test crop. Results revealed that the DTPA-extractable Cd content in soil and Cd concentration in plants decreased significantly with the increasing doses of amendments irrespective of initial soil available Cd and types of amendment used. The effect of amendment was soil specific and in case of Site 1 (low initial Cd) the effect was more prominent. The reduction in DTPA-extractable Cd in combined application of limestone and yellow gypsum @500 mg kg-1 over the absolute control in soil under groundnut for the sites was by far the highest with the values of 83.72%, 77.17%, 48.59% and 40.63% respectively. With the combined application, Target Cancer Risk (TCR) of Cd was also reduced. Hence, combined application of limestone and yellow gypsum can be beneficial in the long run for mitigating Cd pollution.

CRISPR/Cas9-mediated mutagenesis of phytoene desaturase in pigeonpea and groundnut

The CRISPR/Cas9 technology, renowned for its ability to induce precise genetic alterations in various crop species, has encountered challenges in its application to grain legume crops such as pigeonpea and groundnut. Despite attempts at gene editing in groundnut, the low rates of transformation and editing have impeded its widespread adoption in producing genetically modified plants. This study seeks to establish an effective CRISPR/Cas9 system in pigeonpea and groundnut through Agrobacterium-mediated transformation, with a focus on targeting the phytoene desaturase (PDS) gene. The PDS gene is pivotal in carotenoid biosynthesis, and its disruption leads to albino phenotypes and dwarfism. Two constructs (one each for pigeonpea and groundnut) were developed for the PDS gene, and transformation was carried out using different explants (leaf petiolar tissue for pigeonpea and cotyledonary nodes for groundnut). By adjusting the composition of the growth media and refining Agrobacterium infection techniques, transformation efficiencies of 15.2% in pigeonpea and 20% in groundnut were achieved. Mutation in PDS resulted in albino phenotype, with editing efficiencies ranging from 4 to 6%. Sequence analysis uncovered a nucleotide deletion (A) in pigeonpea and an A insertion in groundnut, leading to a premature stop codon and, thereby, an albino phenotype. This research offers a significant foundation for the swift assessment and enhancement of CRISPR/Cas9-based genome editing technologies in legume crops.

Groundnut harbours non-nodulating non-rhizobial plant growth-promoting bacterial endophytes

The present study was carried out to assess the growth-promoting ability of non-rhizobial endophytes in groundnut (Arachis hypogaea). Thirteen endophytic bacteria with different morphologies were isolated from the root and nodules of groundnut. These isolates significantly enhanced the growth of groundnut in sterilised vermiculite, though the isolates were unable to nodulate the host plant. The endophytic nature of these isolates was confirmed by their re-isolation from the sterilised and macerated roots of the plants. The isolates exhibited in vitro tricalcium phosphate and zinc solubilization, production of siderophores, auxins and ammonia as well as growth on different nitrogen-free media. The phosphate solubilization and auxin production varied from 50 to 196 and 17 to 71 µg/ml, respectively by the isolates. Based on phenotypic tests and 16S rRNA gene sequencing, four potential strains were identified as Klebsiella sp. R3, Pseudomonas putida R6, Klebsiella oxytoca GRE5 and Pseudomonas proteolytica GRE6. A significant increase in plant growth, chlorophyll content, nodule count and shoot nutrient content of groundnut was observed with these bacterial inoculations over the uninoculated control in greenhouse. The bacterial treatments resulted in increased N, P and K content in the shoot up to 87, 96 and 44%, respectively, over the control. Physico-chemical properties and available nutrient content of soil were also improved on bacterial inoculations. The results indicated that groundnut harbours beneficial non-rhizobial bacterial endophytes with the potential to be used as microbial inoculants in groundnut. Klebsiella oxytoca as a non-nodulating nodule endophyte of groundnut is reported for the first time.

Assessment of early harvest in the prevention of aflatoxins in peanuts during drought stress conditions

The present study aimed to evaluate the effectiveness of early harvest in preventing aflatoxins in peanuts under drought-stress conditions. A field experiment was conducted on the 2018-2019 and 2019-2020 growing seasons in a greenhouse with an irrigation system to induce three drought stress conditions: no stress, mild, and severe stress. In addition, three harvest dates were proposed: two weeks earlier, one week earlier, and ideal harvest time. The mean peanut yield was 2634 kg/ha, considering the two growing seasons, and the drought stress conditions and harvest dates did not influence significantly. The shelling percentage was significantly higher in samples harvested at ideal harvest (77.7 %) than two weeks earlier (76.2 %) and was not influenced by drought stress conditions. Although a low mean percentage of grains with insect damage was identified, this percentage was statistically higher under severe stress (0.4 %) compared to no-stress conditions (0.2 %). The soil contamination ranged from 2.52 × 103 to 1.64 × 104 CFU/g of Aspergillus section Flavi, and the drought stress resulted in significantly higher concentrations in mild and severe stressed samples. A. section Flavi was found to infect all the peanut kernel samples. The drought stress resulted in higher percentages of A. section Flavi infections in samples from mild and severe stress conditions. The harvest date did not influence the soil and peanut kernel occurrence of A. section Flavi. A total of 435 and 796 strains of A. section Flavi were isolated from soil and peanut kernels, respectively. The potential of aflatoxin production by soil isolates was 31, 44, and 25 % for aflatoxin non-producers, aflatoxin B producers, and aflatoxin B and G producers, respectively, while in peanut kernel isolates were 44, 44, and 12 %. Three different A. section Flavi species were identified from peanut kernels: A. flavus, A. parasiticus, and A. pseudocaelatus. The mean aflatoxin concentration in peanut kernels was 42, 316, and 695.5 μg/kg in samples under no stress, mild stress, and severe stress conditions, respectively. Considering the harvest time, the mean aflatoxin concentration was 9.9, 334.3, and 614.2 μg/kg in samples harvested two weeks earlier, one week earlier, and in ideal harvest, respectively. In conclusion, the early harvest proved to be a viable, cost-free alternative for controlling aflatoxin in the peanut pre-harvest, resulting in a safer product and a better quality for sale and economic gain.

Ethrel-induced release of fresh seed dormancy causes remodelling of amylase activity, proteomics, phytohormone and fatty acid profile of groundnut (Arachis hypogaea L.)

It is important to have a short period of fresh seed dormancy in some of the groundnut species to counter pre-harvest sprouting (PHS). One of the main causes of PHS is the activation of ethylene-mediated pathways. To determine the effect of ethylene, the study was conducted and alterations in amylase, proteins and fatty acids were observed at the 0, 6, 12, and 24 h stages after ethrel administration. The result showed an increase in amylase activity, and the fatty acids profile showed a unique alteration pattern at different germination stages. Two-dimensional gel electrophoresis (2DGE) revealed differential expression of proteins at each stage. The trypsin digestion following spectral development through UPLC-MS/MS enabled identification of number of differentially expressed proteins. A total of 49 proteins were identified from 2DGE excised spots. The majority were belonged to seed storage-related proteins like Arah1, Arah2, AAI- domain containing protein, conglutin, Arah3/4, arachin, glycinin. Expression of lipoxygenase1, lipoxygenase9 and Arah2 genes were further confirmed by qRT-PCR which showed its involvement at transcript level. Up-regulation of lipoxygenase9 is correlated with decreased content of fatty acids during germination. Phytohormone detection revealed decrease in ABA, SA and JA content which are generally inhibitor of seed germination while GA, IAA and kinetin concentration increased revealing positive regulation of seed germination. We present an integrated view of proteomics, phytohormone profile, carbohydrate and lipid metabolism to unravel mechanism of fresh seed dormancy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01332-6.

First draft genome of Thecaphora frezii, causal agent of peanut smut disease

OBJECTIVES

The fungal pathogen Thecaphora frezii Carranza & Lindquist causes peanut smut, a severe disease currently endemic in Argentina. To study the ecology of T. frezii and to understand the mechanisms of smut resistance in peanut plants, it is crucial to know the genetics of this pathogen. The objective of this work was to isolate the pathogen and generate the first draft genome of T. frezii that will be the basis for analyzing its potential genetic diversity and its interaction with peanut cultivars. Our research group is working to identify peanut germplasm with smut resistance and to understand the genetics of the pathogen. Knowing the genome of T. frezii will help analyze potential variants of this pathogen and contribute to develop enhanced peanut germplasm with broader and long-lasting resistance.

DATA DESCRIPTION

Thecaphora frezii isolate IPAVE 0401 (here referred as T.f.B7) was obtained from a single hyphal-tip culture, its DNA was sequenced using Pacific Biosciences Sequel II (PacBio) and Illumina NovaSeq6000 (Nova). Data from both sequencing platforms were combined and the de novo assembling estimated a 29.3 Mb genome size. Completeness of the genome examined using Benchmarking Universal Single-Copy Orthologs (BUSCO) showed the assembly had 84.6% of the 758 genes in fungi_odb10.

An expedient ion chromatography based method for high-throughput analysis of phytic acid in groundnut kernels

A study was made to expedite ion chromatography method using IonPac analytical column and self-regenerating anion suppressor for phytic acid determination in groundnut seeds and compared with a widely adopted spectrophotometric method based on enzymatic hydrolysis. The Ion Chromatography method equipped with AG11 guard and AS11 analytical columns in isocratic mode using 65 mM NaOH mobile phase at 1 mL min-1 flow rate showed a sharp peak for phytic acid with a retention time of 2.42 ± 0.2 min. The peak area was plotted v/s concentration showed linearity with an R2 value of 0.997, detection limit of 0.028 mg L-1 and recovery of 98% as against R2 value of 0.988 and detection limit of 0.065 mg L-1 in the spectrophotometric method. The study demonstrates that Ion Chromatography method was more accurate with a better detection limit than spectrophotometry. Also, this method provides robust handling with lesser reagent requirements due to combined eluent generation and self-regenerating suppression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05527-9.

Participatory variety selection of groundnut (Arachis hypogaea L.) in Taricha Zuriya district of Dawuro Zone, southern Ethiopia

Groundnut is a leguminous seed that contains a lot of oil and protein with high energy content. However, improved varieties were hardly evaluated based on farmers' preference criteria and their participation. Therefore, a participatory variety selection was carried out in Taricha Zuriya district in Dawuro Zone on the mother-baby approach on farmers' fields in the 2019 and 2020 main cropping seasons, aiming at evaluating the performance of groundnut varieties through farmers' participation and assessing their preference criteria. Six released groundnut varieties were tested using a randomized complete block design with four replicates at farmers' fields. The mother trial was done at one model farmer field (all four replications on one field), whereas the baby trials were done at four farmers' fields by considering farmers as replication per village. Combined analysis of variance for two years showed a highly significant (P < 0.001) to significant (P < 0.01) differences among groundnut varieties for grain yield, days to 50 % flowering, days to maturity, seeds per pod, pods per plant, 100 seed weight, except for both stand count at emergence and harvest. Among the tested varieties, BaHajidu (1805.84 kg ha^-1) was identified as the best yielding groundnut variety, followed by Bulki-01 (1805.50 kg ha^-1) and Werer-963 (1780.0 kg ha^-1), respectively, while Werer-962 variety has a lower yield (1536.30 kg ha^-1). Bulki-01 (96), BaHajidu (90), and Werer- 963 (76) obtained higher score values as preferred by farmers, whereas lower score values were observed for Manipinter variety (45). The aforementioned varieties Bulki-01, BaHajidu and Werer-963 were also preferred using selection criteria set by farmers as 1^st, 2^nd, and 3^rd in rank order respectively. Hence, based on farmers' preference values and biological data, these three groundnut varieties were recommended for pre-extension demonstration and large-scale production in Dawuro Zone and areas with similar agro-ecologies.

Mycobiota profile, phenology, and potential toxicogenic and pathogenic species associated with stored groundnuts (Arachis hypogaea L.) from the Volta Region, Ghana

This study updates the mycobiota resident in groundnut seeds, their phenology during storage with the view to ascertain their occurrence, potential toxigenic species, and pathologically important species in the stored samples. The moisture content of the seeds ranged from 5.7% to 6.5% within the stipulated safe moisture content of 8% for extension of shelf life. Culturing the seeds on mycological media (Sabouraud's Dextrose Agar SDA; Oxytetracycline Glucose Yeast Extract OGYE, Potato Dextrose Agar, PDA) caused a de novo growth of the quiescent spores at 28-30°C for 7-14 days. Fungal population counts on the three media ranged from 2.01 to 2.16 log₁₀ CFU/g samples to a final 6-month count of 1.67-2.60 log₁₀ CFU/g. Eighteen different fungal species belonging to ten genera were encountered on the media, namely Aspergillus, Cladosporium, Curvularia, Fusarium, Penicillium, Trichoderma, Rhizopus, Rhodotorula, Sporendonema, and Paecilomyces. Aspergillus spp. (A. niger, A. flavus, A. fumigatus, and A. terreus) were the most frequently isolated, followed by Fusarium species (F. oxysporum, F. solani, and F. verticillioides), Trichoderma (T. harzianum and T. viride), Rhizopus spp (R. oligosporus and R. stolonifer), and Penicillium verrucosum. The species which were seed borne (A. niger, A. flavus, A. terreus, A. fumigatus, F. solani, F. verticillioides, T. viride, C. herbarum, and Curvularia lunata) were isolated on both surface sterilized and non-surface sterilized seeds. The phenology of the encountered fungal species generally followed five patterns. The most frequently isolated Aspergillus niger, A. flavus, and A. fumigatus predominated throughout the 6 months sampling period, while A. ustus and A. terreus appeared sporadically and disappeared. The early colonizers (R. oligosporus, R. stolonifer, and Paecilomyces) could not be isolated after 2-3 months owing presumably to stronger antibiosis competition from the Aspergillus species. The most predominant Aspergillus species initially constituted 36%-48% of the total population but declined to 10%-36% in 6 months. Mycobiota encountered with mycotoxigenic potential and human health importance were A. niger, A. flavus, A. fumigatus, F. verticillioides, and Penicillium verrucosum. Other species of pathological importance to plants were Curvularia lunata and Fusarium oxysporum. The practical implications of these findings are discussed.

Genetic mapping and QTL analysis for peanut smut resistance

BACKGROUND

Peanut smut is a disease caused by the fungus Thecaphora frezii Carranza & Lindquist to which most commercial cultivars in South America are highly susceptible. It is responsible for severely decreased yield and no effective chemical treatment is available to date. However, smut resistance has been identified in wild Arachis species and further transferred to peanut elite cultivars. To identify the genome regions conferring smut resistance within a tetraploid genetic background, this study evaluated a RIL population {susceptible Arachis hypogaea subsp. hypogaea (JS17304-7-B) × resistant synthetic amphidiploid (JS1806) [A. correntina (K 11905) × A. cardenasii (KSSc 36015)] × A. batizocoi (K 9484)^4×} segregating for the trait.

RESULTS

A SNP based genetic map arranged into 21 linkage groups belonging to the 20 peanut chromosomes was constructed with 1819 markers, spanning a genetic distance of 2531.81 cM. Two consistent quantitative trait loci (QTLs) were identified qSmIA08 and qSmIA02/B02, located on chromosome A08 and A02/B02, respectively. The QTL qSmIA08 at 15.20 cM/5.03 Mbp explained 17.53% of the phenotypic variance, while qSmIA02/B02 at 4.0 cM/3.56 Mbp explained 9.06% of the phenotypic variance. The combined genotypic effects of both QTLs reduced smut incidence by 57% and were stable over the 3 years of evaluation. The genome regions containing the QTLs are rich in genes encoding proteins involved in plant defense, providing new insights into the genetic architecture of peanut smut resistance.

CONCLUSIONS

A major QTL and a minor QTL identified in this study provide new insights into the genetic architecture of peanut smut resistance that may aid in breeding new varieties resistant to peanut smut.

Metabolic profiling for dissection of late leaf spot disease resistance mechanism in groundnut

Late leaf spot (LLS) caused by fungi Passalora personata is generally more destructive and difficult to control than early leaf spot. The aim of this study was to decipher biochemical defense mechanism in groundnut genotypes against P. personata by identifying resistance specific biomarkers and metabolic pathways induced during host-pathogen interaction. Metabolomics of non-infected and infected leaves of moderately resistant (GPBD4 and ICGV86590), resistant (KDG128 and RHRG06083) and susceptible (GG20, JL24 and TMV2) genotypes was carried out at 5 days after infection (65 days after sowing). Non-targeted metabolite analysis using GC-MS revealed total 77 metabolites including carbohydrates, sugar alcohols, amino acids, fatty acids, polyamines, phenolics, terpenes and sterols. Variable importance in projection (VIP) measure of partial least squares-discriminant analysis (PLS-DA) showed that resistant and moderately resistant genotypes possessed higher intensities of ribonic acid, cinnamic acid, malic acid, squalene, xylulose, galactose, fructose, glucose, β-amyrin and hydroquinone while susceptible genotypes had higher amount of gluconic acid 2-methoxime, ribo-hexose-3-ulose and gluconic acid. Heat map analysis showed that resistant genotypes had higher intensities of β-amyrin, hydroquinone in non-infected and malic acid, squalene, putrescine and 2,3,4-trihydroxybutyric acid in infected leaves. Dendrogram analysis further separated resistant genotypes in the same cluster along with infected moderately resistant genotypes. The most significant pathways identified are: linoleic acid metabolism, flavone and flavonol biosynthesis, cutin, suberin and wax biosynthesis, pentose and glucuronate interconversions, starch and sucrose metabolism, stilbenoid biosynthesis and ascorbate and aldarate metabolism. Targeted metabolite analysis further confirmed that resistant genotypes possessed higher content of primary metabolites sucrose, glucose, fructose, malic acid and citric acid. Moreover, resistant genotypes possessed higher content of salicylic, coumaric, ferulic, cinnamic, gallic acid (phenolic acids) and kaempferol, quercetin and catechin (flavonols). Thus metabolites having higher accumulation in resistant genotypes can be used as biomarkers for screening of LSS resistant germplasm. These results unravel that higher amount of primary metabolites leads to stimulate the accumulation of more amounts of secondary metabolites such as phenolic acid, flavanols, stilbenes and terpenoids (squalene and β-amyrin) biosynthesis which are ultimately involved in defense mechanism against LLS pathogen.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-021-00985-5.

Comprehensive analysis and identification of drought-responsive candidate NAC genes in three semi-arid tropics (SAT) legume crops

Background

Chickpea, pigeonpea, and groundnut are the primary legume crops of semi-arid tropics (SAT) and their global productivity is severely affected by drought stress. The plant-specific NAC (NAM - no apical meristem, ATAF - Arabidopsis transcription activation factor, and CUC - cup-shaped cotyledon) transcription factor family is known to be involved in majority of abiotic stresses, especially in the drought stress tolerance mechanism. Despite the knowledge available regarding NAC function, not much information is available on NAC genes in SAT legume crops.

Results

In this study, genome-wide NAC proteins – 72, 96, and 166 have been identified from the genomes of chickpea, pigeonpea, and groundnut, respectively, and later grouped into 10 clusters in chickpea and pigeonpea, while 12 clusters in groundnut. Phylogeny with well-known stress-responsive NACs in Arabidopsis thaliana, Oryza sativa (rice), Medicago truncatula, and Glycine max (soybean) enabled prediction of putative stress-responsive NACs in chickpea (22), pigeonpea (31), and groundnut (33). Transcriptome data revealed putative stress-responsive NACs at various developmental stages that showed differential expression patterns in the different tissues studied. Quantitative real-time PCR (qRT-PCR) was performed to validate the expression patterns of selected stress-responsive, Ca_NAC (Cicer arietinum - 14), Cc_NAC (Cajanus cajan - 15), and Ah_NAC (Arachis hypogaea - 14) genes using drought-stressed and well-watered root tissues from two contrasting drought-responsive genotypes of each of the three legumes. Based on expression analysis, Ca_06899, Ca_18090, Ca_22941, Ca_04337, Ca_04069, Ca_04233, Ca_12660, Ca_16379, Ca_16946, and Ca_21186; Cc_26125, Cc_43030, Cc_43785, Cc_43786, Cc_22429, and Cc_22430; Ah_ann1.G1V3KR.2, Ah_ann1.MI72XM.2, Ah_ann1.V0X4SV.1, Ah_ann1.FU1JML.2, and Ah_ann1.8AKD3R.1 were identified as potential drought stress-responsive candidate genes.

Conclusion

As NAC genes are known to play role in several physiological and biological activities, a more comprehensive study on genome-wide identification and expression analyses of the NAC proteins have been carried out in chickpea, pigeonpea and groundnut. We have identified a total of 21 potential drought-responsive NAC genes in these legumes. These genes displayed correlation between gene expression, transcriptional regulation, and better tolerance against drought. The identified candidate genes, after validation, may serve as a useful resource for molecular breeding for drought tolerance in the SAT legume crops.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07602-5.

Genomics assisted functional characterization of Paenibacillus polymyxa HK4 as a biocontrol and plant growth promoting bacterium

The diseases caused by phytopathogens account for huge economic losses in the agricultural sector. Paenibacillus polymyxa is one of the agriculturally important biocontrol agents and plant growth promoting bacterium. This study describes the antifungal potential of P. polymyxa HK4 against an array of fungal phytopathogens and its ability to stimulate seed germination of cumin and groundnut under in vitro conditions. The cumin and groundnut seeds bacterized with HK4 exhibited enhanced germination efficiency in comparison to controls. The use of HK4 as a soil inoculant significantly promoted the shoot length and fresh weight of groundnut plants in pot studies. The draft genome analysis of HK4 revealed the genetic attributes for motility, root colonization, antagonism, phosphate solubilization, siderophore production and production of volatile organic compounds. The bacterium HK4 harnessed several hydrolytic enzymes that may assist its competence in the rhizosphere. The PCR amplification and sequence analysis of the conserved region of the fusA gene amplicon revealed the ability of HK4 to produce fusaricidin. Furthermore, the LC-ESI-MS/MS of crude cell pellet extract of HK4 confirmed the presence of fusaricidin as a major antifungal metabolite. This study demonstrated the potential of HK4 as a biocontrol agent and a plant growth promoter.

Factors affecting groundnut market supply in Western Oromia, Ethiopia

Groundnut production is important for consumption, income generation and improves food security of smallholder farmers in Western Oromia. Unlike its importance its production has less concern and it's marketing is challenged by the amount produced. The study aimed to analyze determinants of groundnut market supply in western Oromia region, Ethiopia. In order to do this, both primary and secondary data were used to collect qualitative and quantitative data. A multi-stage sampling technique was used to select samples of groundnut producers from the study area. Primary data were collected from randomly select 400 sampled groundnut producers through a semi-structured questionnaire. The multiple linear regression models was used to analyze determinants of groundnut market supply. The results of the model indicated that age, sex, educational level, access to credit services, number of livestock owned, land allocated for groundnut production and distance from the nearest market statistically and significantly affected market supply of the groundnut. Therefore, the study forward that government, non-governmental organization and financial institutions should give attention to grant credit, train farmers to properly utilize their land, develop and strengthening infrastructural service like road to improve groundnut production and sales thereby to increase benefits of farmers from the groundnut production in Western Oromia.

South India projected to be susceptible to high future groundnut failure rates for future climate change and geo-engineered scenarios

With an increase in global mean temperature predicted for this century accompanied by more frequent extremes, will farming communities need to brace for increased crop failures and hardship? Solar dimming climate geoengineering has been proposed as a possible solution to combat rising global temperature but what effect will it or other climate related adaptation have on crop failures? We performed a crop modelling study using future climate and geoengineering projections to investigate these questions. Our results indicate that groundnut crop failure rates in Southern India are very sensitive to climate change, and project an increase of approximately a factor of two on average over this century, affecting one out of every two to three years instead of one in every five years. We also project that solar dimming geoengineering will have little impact on reducing these failure rates. In contrast, the projections for the rest of Indian regions show decreasing failure rates of 20-30%. In this research, we indicate why south India is more susceptible than the rest of the country and show that neither Solar dimming geoengineering nor reducing heat or water stress are able to fully counteract the increase in failure rates for this region. Thus our modelling projections indicate the potential for a grountnut crop failure crisis for the South India.

Low-cost grain sorting technologies to reduce mycotoxin contamination in maize and groundnut

The widespread contamination of foods by mycotoxins continues to be a public health hazard in sub-Saharan Africa, with maize and groundnut being major sources of contamination. This study was undertaken to assess the hypothesis that grain sorting can be used to reduce mycotoxin contamination in grain lots by removing toxic kernels. We tested a set of sorting principles and methods for reducing mycotoxin levels in maize and groundnut from a variety of genotypes and environments. We found that kernel bulk density (KBD) and 100-kernel weight (HKW) were associated with the levels of aflatoxins (AF) and fumonisins (FUM) in maize grain. A low-cost sorter prototype (the ‘DropSort’ device) that separated maize grain based on KBD and HKW was more effective in reducing FUM than AF. We then evaluated the effectiveness of DropSorting when combined with either size or visual sorting. Size sorting followed by DropSorting was the fastest method for reducing FUM to under 2 ppm, but was not effective in reducing AF levels in maize grain to under 20 ppb, especially for heavily AF-contaminated grain. Analysis of individual kernels showed that high -AF maize kernels had lower weight, volume, density, length, and width and higher sphericity than those with low AF. Single kernel weight was the most significant predictor of AF concentration. The DropSort excluded kernels with lower single kernel weight, volume, width, depth, and sphericity. We also found that visual sorting and bright greenish-yellow fluorescence sorting of maize single kernels were successful in separating kernels based on AF levels. For groundnut, the DropSort grouped grain based on HKW and did not significantly reduce AF concentrations, whereas size sorting and visual sorting were much more effective.

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The DropSort prototype was more effective in reducing fumonisins than aflatoxins.

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DropSorting following size sorting was effective in reducing fumonisins below 2 ppm.

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Visual sorting was more effective in reducing fumonisins than aflatoxins in maize.

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Size and visual sorting separated groundnut grain based on aflatoxin levels.

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Single kernel mass is the most significant determinant of AF levels.

Field efficacy of two atoxigenic biocontrol products for mitigation of aflatoxin contamination in maize and groundnut in Ghana

Biological control is one of the recommended methods for aflatoxin mitigation. Biocontrol products must be developed, and their efficacy demonstrated before widespread use. Efficacy of two aflatoxin biocontrol products, Aflasafe GH01 and Aflasafe GH02, were evaluated in 800 maize and groundnut farmers' fields during 2015 and 2016 in the Ashanti, Brong Ahafo, Northern, Upper East, and Upper West regions of Ghana. Both products were developed after an extensive examination of fungi associated with maize and groundnut in Ghana. Each product contains as active ingredient fungi four Aspergillus flavus isolates belonging to atoxigenic African Aspergillus Vegetative Compatibility Groups (AAVs) widely distributed across Ghana. An untreated field was maintained for each treated field to determine product efficacy. Proportions of atoxigenic AAVs composing each product were assessed in soils before product application, and soils and grains at harvest. Significant (P < 0.05) displacement of toxigenic fungi occurred in both crops during both years, in all five regions. Biocontrol-treated crops consistently had significantly (P < 0.05) less aflatoxins (range = 76% to 100% less; average = 99% less) than untreated crops. Results indicate that both biocontrol products are highly efficient, cost-effective, environmentally safe tools for aflatoxin mitigation. Most crops from treated fields could have been sold in both local and international food and feed premium markets. Adoption and use of biocontrol products have the potential to improve the health of Ghanaians, and both income and trade opportunities of farmers, aggregators, distributors, and traders.

Identification of novel QTLs for late leaf spot resistance and validation of a major rust QTL in peanut (Arachis hypogaea L.)

Co-occurrence of two devastating foliar-fungal diseases of peanut, viz., late leaf spot (LLS), and rust may cause heavy yield loss besides adversely affecting the quality of kernel and fodder. This study reports the mapping of seven novel stress-related candidate EST-SSRs in a region having major QTLs for LLS and rust diseases using an F₂ mapping population (GJG17 × GPBD4) consisting of 328 individuals. The parental polymorphism using 1311 SSRs revealed 84 SSRs (6.4%) as polymorphic and of these 70 SSRs could be mapped on 14 linkage groups (LG). QTL analysis has identified a common QTL (LLS_QTL1/Rust_QTL) for LLS and rust diseases in the map interval of 1.41 cM on A03 chromosome, explaining 47.45% and 70.52% phenotypic variations, respectively. Another major QTL for LLS (LLS_QTL1), explaining a 29.06% phenotypic variation was also found on LG_A03. A major rust QTL has been validated which was found harboring R-gene and resistance-related genes having a role in inducing hypersensitive response (HR). Further, 23 linked SSRs including seven novel EST-SSRs were also validated in 177 diverse Indian groundnut genotypes. Twelve genotypes resistant to both LLS and rust were found carrying the common (rust and LLS) QTL region, LLS QTL region, and surrounding regions. These identified and validated candidate EST-SSR markers would be of great use for the peanut breeding groups working for the improvement of foliar-fungal disease resistance.

Effect of starter nitrogen and phosphorus fertilizer rates on yield and yield components, grain protein content of groundnut (Arachis Hypogaea L.) and residual soil nitrogen content in a semiarid north Ethiopia

Increasing costs of chemical fertilizers, environmental concerns of their application and demand for protein foods, placed an extensive interest in growing of legume crops for human nutrition, and soil fertility replenishment. This study was conducted to investigate the effects of nitrogen (N) and phosphorus (P) fertilizers on parameters of phenology, growth performance, grain yield, yield components, grain protein content of groundnut, and residual soil nitrogen content in the northern Ethiopia during the growing season of 2017. Three levels of N (0, 15 and 30 kg ha^-1) and four levels of P₂O₅ (0, 23, 46 and 69 kg ha^-1) were set in factorial combinations of randomized complete block design with three replications. Results showed that an average total biomass yield increased by 22.5% for separate individual application of 15 kg N ha^-1 and by 16.6% for 46 kg P₂O₅ ha^-1 compared to control plots. Haulm yield increased by 29.17% for plots treated with N fertilization compared to control plots. Average pod yield increased by 85.4% for a combined application of 15 kg N ha^-1 and 46 kg P₂O₅ ha^-1 fertilizers compared to the control plots. Plots fertilized with the highest combined rates of N and P have attained lower grain yield compared to the combined application of 15 kg N ha^-1 and 46 kg P₂O₅ ha^-1. The highest grain protein contents were obtained for a combined application of 30 kg N ha^-1 and zero P, and 15 kg N ha^-1 plus 46 kg P₂O₅ ha^-1. The highest N harvest index was obtained for control treatments and for plots treated with combined application of 15 kg N ha^-1 and 46 kg P₂O₅ ha^-1. Residual soil N content increased by 119% on plots with combined application of 15 kg N ha^-1 and 46 P₂O₅ ha^-1 compared to control plots. Based on our results, combined application of 15 kg N ha^-1 and 46 kg P₂O₅ ha^-1 was recommended for increasing grain yield, grain protein content and residual soil nitrogen. The results of this study are crucial to improve groundnut productivity, grain protein content and also to provide implication on soil fertility management in a crop rotation system.

Molecular and phenotypic diversity of groundnut (Arachis hypogaea L.) cultivars in Togo

Diversity assessment of 94 groundnut accessions from Togo and Senegal, using agro-morphological and SNP markers, revealed high variability for many quantitative traits such as late leaf spot (LLS) incidence, number of pods per plant and yield per plant. For qualitative traits, the Simpson Index showed high diversity for primary seed colour (0.75), stem pigmentation (0.60), and Growth habit (0.59). Principal component analysis underscored quantitative traits such as hundred seed weight, days to maturity, and LLS incidence, as the main traits contributing to the divergence. Correlation and path coefficient analysis showed that the number of pods per plant was the main yield-related trait positively affecting yield (r = 0.95, PC = 0.84; p = 0.01). Overall, 990 SNP markers revealed moderate genetic variability in the genotypes and the percentage of heterozygous genotypes varied from 0 to 50% for all loci. Analysis of molecular variance revealed that only 1.1% of the total molecular variance accounted for geographical contribution to the diversity. Co-analysis of phenotypic and SNP data delineated three clusters harbouring useful alleles and interesting phenotypic features such as LLS resistance, large number of pods per plant and early maturity indicating that differences observed at the phenotypic level are underlined by genotypic differences. The phenotypic and genotypic diversity observed could be exploited for the identification of parents with preferred traits for use in the breeding program. However, the low population structure highlights the necessity to improve groundnut diversity in Togo through introduction from various sources.

RNA sequence analysis of diseased groundnut (Arachis hypogaea) reveals the full genome of groundnut rosette assistor virus (GRAV)

The complete genome sequences for two variant isolates of groundnut rosette assistor virus (GRAV) have been determined from symptomatic groundnut plants in western Kenya. The sequences of the two GRAV isolates (sc7.1 and sc7.2) are 84.2% identical at the nucleotide level and 98.5% identical at the coat protein level. The variants sc7.1 and sc7.2 comprise 5850 and 5879 nucleotides respectively, and show similar genome organizations with 7 predicted ORFs (P0, P1, P2, P3a, P3 (coat protein, CP), P4 (movement protein, MP) and P5 (coat protein-readthrough protein, CP-RT). Currently, GRAV is an unassigned virus in the Luteoviridae family, due to the fact that only the sequence of the coat protein was previously obtained. The presence of both ORF0 and ORF 4 within the genome sequence determined in the current work suggest that GRAV should be classified as a member of the genus Polerovirus.

Distinguish metabolic profiles and defense enzymes in Alternaria leaf blight resistant and susceptible genotypes of groundnut

Alternaria leaf blight is major fungal disease of summer groundnut, causes significant loss of haulm and pod yield. Aims of this study were to understand the role of metabolites and phenylpropanoid related enzymes in Alternaria leaf blight resistance and to find out metabolic marker for disease resistance. Alternaria leaf blight resistant (GPBD4 and CS186) and susceptible genotypes (GG2 and TPG41) of groundnut were grown in pots during rabi-summer 2015. Groundnut plants were infected with Alternaria alternata (Fr.) Keissler at 40 days after sowing. 5 days after infection, upper second leaves were collected from both control and infected plants for analysis. A total of 67 metabolites comprising sugars, sugar alcohols, amino acids, organic acids, fatty acids, sterols and phenolic were identified using gas chromatography-mass spectrometry (non-targeted metabolomics). Constitutive levels of alpha-d-galactoside, d-mannitol, d-erythropentitol, glycine, and hexadecanoic acid were observed higher in resistant genotypes compared to susceptible genotypes. Moreover, arabinofuranose, cinnamic acid, 2-butendioic acid, and linoleic acid were observed only in resistant genotypes at both control and infected stage. In susceptible genotypes myo-inositol, glucose and fructose content was increased after infection with pathogen while decreased in resistant genotypes. Resistant genotypes had higher constitutive level of cinnamic and salicylic acid compared to susceptible genotypes. Non-infected leaves of resistant genotypes also had higher activities of phenylalanine ammonia lyase and tyrosine ammonia lyase activities. Our results suggest that metabolites specifically present in resistant genotypes impart defense mechanism against Alternaria pathogen and can be used as bio-marker for screening of germplasm.

Evaluation of cytotoxicity, biochemical profile and yield components of groundnut plants treated with nano-selenium

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Preparation and Characterization of selenium nanoparticles.

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Foliar application of the prepared nano-selenium on 3 different groundnut (Arachis hypogaea L.) cultivars.

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Evaluation of the effect of nanoselenium on Growth parameters, lipid peroxidation, antioxidants enzymes.

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Evaluation of prepared nano-selenium cytotoxicity.

Knowledge about the risks of the nanoparticles application on the plant development and human health is still limited. Different concentrations of nano-selenium (0, 20 and 40 ppm) were applied to three different Egyptian groundnut (Arachis hypogaea l.) cultivars; (NC, Gregory and Giza 6) under sandy soil conditions at vegetative growth stage to investigate their effects on yield components, protein profile, fatty acids composition, total antioxidant content and cytotoxicity of yielded seeds. The results indicate that the tested Nano-Selenium (Nano-Se) concentrations improved yield components and seeds oil. However, Nano-Se altered protein signatures as well as fatty acids composition by increasing unsaturated fatty acids and/or decreasing saturated fatty acids as compared with control, the cytotoxicity assessments proved safety of the yield for human health.

Development of high oleic peanut lines through marker-assisted introgression of mutant ahFAD2 alleles and its fatty acid profiles under open-field and controlled conditions

Peanut is one of the most important oilseed crops grown worldwide. In this study, the mutant ahFAD2 alleles conferring high oleic (HO) content are introgressed into an elite Indian cultivar GPBD4 which is also resistant to the foliar fungal diseases like rust and late leaf spot (LLS). The allele-specific PCR (AS-PCR) and cleaved amplified polymorphic sequences (CAPS) assays were used for the marker-assisted backcross (MABC) approach and 64 HO introgression lines (ILs) were generated. These ILs were tested for the FA compositions under the glasshouse and field conditions. The oleic acid and linoleic acid contents in the ILs were recorded to be between 68.94-82.33% and 1.74-10.87%, respectively, under glasshouse and 67.04-81.71% and 2.00-15.66%, respectively, under field conditions. The increase in the oleic acid content of the ILs over its recurrent parent (RP) was recorded to the tune of 28.78-53.80% and 33.70-62.96% under glasshouse and field conditions, respectively, indicating the stable expression of ahFAD2B gene in two different environments. On the contrary, linoleic acid showed 56.47-93.03% and 40.02-92.34% reduction in the ILs over its RP under glasshouse and field conditions, respectively. These ILs with a healthy FA profile can meet not only the nutritional requirements of a health-conscious society but also the industrial demands for better shelf life of oil and its products.

Groundnut production constraints and farmers' trait preferences: a pre-breeding study in Togo

BACKGROUND

Groundnut is an important legume crop in Togo. However, groundnut yield has been steadily decreasing for decades as a result of lack of organized breeding program to address production constraints. Though, low yielding varieties and late leaf spot have been often reported as the most important constraints, there is no documented evidence. Identifying and documenting the major production constraints is a prerequisite for establishing a good breeding program with clearly defined priority objectives and breeding strategies. Thus, the objectives of this study were to identify groundnut production constraints and assess farmers' preferred traits.

METHODS

A participatory rural appraisal approach was used to collect data on agronomic practices, farmers' preferences, and possible threats to production through individual and group interviews. Three regions and three villages per region were selected based on the representativeness of groundnut production systems. In each village, 20 farmers were randomly selected and interviewed; thus, a total of 180 farmers were interviewed. Content analysis was carried out for qualitative data and for quantitative data generated within and across regions, comparative descriptive statistics were carried out. Differences in perception and preferences were assessed using chi-square tests.

RESULTS

The study has revealed that, though there were some variation across the regions, traits pertaining to yield such as pod yield (66.66%) and pod size (12.12%) were the most important. Leaf spot diseases, rosette and peanut bud necrosis (37.77%) and insects such as pod sucking bug and bruchid (27.77%) were considered to be the most important constraints limiting groundnut production. Among diseases, farmers in all the three regions indicated that late leaf spot is of economic importance which they associated to various causes such as maturity, drought, or insects. No gender differences were observed for the perception of constraints and groundnut traits preferences. Land size is significantly influenced by age and gender. Besides, farmers have pointed the lack of improved varieties and the unavailability of groundnut seeds highlighting the necessity of a sustainable groundnut seed system linked with a strong breeding program.

CONCLUSION

This study has enabled understanding of the farming practices, constraints, and farmers preferred characteristics, thus providing the basis for a participatory breeding program in Togo which should consider that farmers perceive low yielding varieties and diseases as major constraints to production.

Complete genome sequence and phylogenetic relationships of tobacco streak virus causing groundnut stem necrosis disease in India

Tobacco streak virus (TSV, genus Ilarvirus family Bromoviridae) is known to cause stem necrosis disease (SND) in groundnut (Arachis hypogaea) since 2000 in Southern India. The TSV isolate infecting groundnut so far has not been characterized based on the complete genome sequence. In this study, TSV was isolated from a naturally infecting groundnut plant in Kadiri, the hot-spot of the SND in southern India. During the Kharif season of 2014, groundnut plants in an experimental field were affected with chlorosis and necrosis in leaf, stem and buds. The cent percent of the 48 samples with these symptoms collected from the field tested positive for TSV in ELISA samples in this context. One isolate, GN-Kad was established from a single lesion on cowpea cv. C-152 through successive sap inoculation. Cloning and sequencing of coat protein gene (717 nucleotides) of the isolate showed high sequence identity (98-99%) with the TSV isolates reported from different crops in India. The isolate produced local necrotic rings or veinal necrosis following sap inoculation to cowpea (cultivars C-152, Pusa Komal, Pusa Sukomal and Krishi Kanchan), French bean and sunflower; whereas, it produced systemic chlorotic mottling symptoms in Nicotiana benthamiana. The three segments of the virus genome (RNA 1, RNA 2 and RNA 3) contained 3523, 2903 and 2232 nucleotides, respectively. The overall genome sequence (8639 nt) of the present isolate shared 77-99% of nucleotide sequence identity with that of the other seven isolates reported from Australia, India and USA. The GN-Kad shared very close phylogenetic relationship with the okra and pumpkin isolates reported from India. The present report is the first comprehensive study of the molecular characterization of TSV associated with the stem necrosis disease of groundnut.

Genetic imprints of domestication for disease resistance, oil quality, and yield component traits in groundnut (Arachis hypogaea L.)

Ploidy difference between wild Arachis species and cultivated genotypes hinder transfer of useful alleles for agronomically important traits. To overcome this genetic barrier, two synthetic tetraploids, viz., ISATGR 1212 (A. duranensis ICG 8123 × A. ipaensis ICG 8206) and ISATGR 265-5A (A. kempff-mercadoi ICG 8164 × A. hoehnei ICG 8190), were used to generate two advanced backcross (AB) populations. The AB-populations, namely, AB-pop1 (ICGV 91114 × ISATGR 1212) and AB-pop2, (ICGV 87846 × ISATGR 265-5A) were genotyped with DArT and SSR markers. Genetic maps were constructed for AB-pop1 and AB-pop2 populations with 258 loci (1415.7 cM map length and map density of 5.5 cM/loci) and 1043 loci (1500.8 cM map length with map density of 1.4 cM/loci), respectively. Genetic analysis identified large number of wild segments in the population and provided a good source of diversity in these populations. Phenotyping of these two populations identified several introgression lines with good agronomic, oil quality, and disease resistance traits. Quantitative trait locus (QTL) analysis showed that the wild genomic segments contributed favourable alleles for foliar disease resistance while cultivated genomic segments mostly contributed favourable alleles for oil quality and yield component traits. These populations, after achieving higher stability, will be useful resource for genetic mapping and QTL discovery for wild species segments in addition to using population progenies in breeding program for diversifying the gene pool of cultivated groundnut.

N2-fixation and N contribution by grain legumes under different soil fertility status and cropping systems in the Guinea savanna of northern Ghana

Continuous cereal-based cropping has led to a rapid decline in soil fertility in the Guinea savanna agro-ecological zone of northern Ghana with corresponding low crop yields. We evaluated the effects of cropping system and soil fertility status on grain yields and N₂-fixation by grain legumes and net N contribution to soil fertility improvement in contrasting sites in this agro-ecological zone. Maize was intercropped with cowpea, soybean and groundnut within a row, with a maize stand alternated with two equally spaced cowpea or groundnut stands and in the maize-soybean system, four equally spaced soybean stands. These intercrops were compared with sole crops of maize, cowpea, soybean and groundnut in fertile and poorly fertile fields at sites in the southern (SGS) and the northern (NGS) Guinea savanna. The proportion of N derived from N₂-fixation (%Ndfa) was comparable between intercrops and sole crops. However, the amount of N₂-fixed was significantly larger in sole crops due to a greater biomass accumulation. Legumes in poorly fertile fields had significantly smaller shoot δ¹⁵N enrichment (-2.8 to +0.7‰) and a larger %Ndfa (55-94%) than those in fertile fields (-0.8 to +2.2‰; 23-85%). The N₂-fixed however was larger in fertile fields (16-145 kg N ha^-1) than in poorly fertile fields (15-123 kg N ha^-1) due to greater shoot dry matter and N yields. The legumes grown in the NGS obtained more of their N requirements from atmospheric N₂-fixation (73-88%) than legumes grown in the SGS (41-69%). The partial soil N balance (in kg ha^-1) was comparable between intercrops (-14 to 21) and sole legumes (-8 to 23) but smaller than that of sole maize receiving N fertiliser (+7 to +34). With other N inputs (aerial deposition) and outputs (leaching and gaseous losses) unaccounted for, there is uncertainty surrounding the actual amount of soil N balances of the cropping systems, indicating that partial N balances are not reliable indicators of the sustainability of cropping systems. Nevertheless, the systems with legumes seem more attractive due to several non-N benefits. Our results suggest that soybean could be targeted in the SGS and cowpea in the NGS for greater productivity while groundnut is suited to both environments. Grain legumes grown in poorly fertile fields contributed more net N to the soil but growing legumes in fertile fields seems more lucrative due to greater grain and stover yields and non-N benefits.

Diversity of culturable methylotrophic bacteria in different genotypes of groundnut and their potential for plant growth promotion

This study aimed at documenting the culturable methylotrophic bacterial diversity across different groundnut genotypes and evaluating their effect on the growth of groundnut. 80 methylotrophic bacterial isolates were obtained from the phyllosphere of 15 groundnut genotypes collected from Tamil Nadu, India. The bacterial isolates were identified through sequencing of the 16S rDNA and were tested for their plant growth-promoting properties. Groundnut seeds were inoculated with methylotrophic bacteria and their effect on growth was evaluated via in vitro and pot experiments. Molecular identification revealed that the isolates belonged to 30 different species. A higher diversity of methylotrophic bacteria at genus and species level was found in groundnut genotype TMV2. Shannon diversity index was the highest in genotype TMV7, followed by VRI2 and TMV2. Similarly, geographical location also influenced the diversity of methylotrophic bacteria. In vitro seed germination assay revealed that methylotrophic isolates enhanced root growth and improved formation of root hair. The radicle length of treated seeds ranged from 2.7 to 8.4 cm. A higher shoot length was observed in the plants from seeds treated with Methylobacterium radiotolerans VRI8-A4 (27.3 cm), followed by Pseudomonas psychrotolerans TMV13-A1 (26.3 cm) and Bacillus aryabhattai K-CO3-3 (23 cm). The findings of this study strongly suggest that beneficial methylotrophic bacteria associated with the phyllosphere of groundnut play a major role in regulating plant growth.

Trade-offs and synergies between yield, labor, profit, and risk in Malawian maize-based cropping systems

Land degradation, population growth, and chronic poverty in Eastern and Southern Africa challenge the sustainability of livelihoods for smallholder farmers. These farmers often manage soils depleted of nutrients, apply limited amounts of mineral fertilizer, and take decisions about their cropping systems that involve multiple trade-offs. The rotation of cereals with legumes bears agronomic and ecological merit; however, the socio-economic implications of the cereal-legume rotation require a deeper understanding. This study explores the yield, labor, profit, and risk implications of different legume and mineral fertilizer practices in maize-based cropping systems in central Malawi. Our method involves coupling crop modeling and an agricultural household survey with a socio-economic analysis. We use a process-based cropping systems model to simulate the yield effects of integrating legumes into maize monocultures and applying mineral fertilizer over multiple seasons. We combine the simulated yields with socio-economic data from an agricultural household survey to calculate indicators of cropping-system performance. Our results show that a maize-groundnut rotation increases average economic profits by 75% compared with maize monoculture that uses more mineral fertilizer than in the rotation. The maize-groundnut rotation increases the stability of profits, reduces the likelihood of negative profits, and increases risk-adjusted profits. In contrast, the maize-groundnut rotation has a 54% lower average caloric yield and uses more labor than the maize monoculture with mineral fertilization. By comparing labor requirements with labor supply at the household scale, we show for the first time that the additional labor requirements of the maize-groundnut rotation can increase the likelihood of experiencing a labor shortage, if this rotation is undertaken by farm households in central Malawi. We demonstrate that risk and labor factors can be important when examining trade-offs among alternative cropping systems.

SSR markers associated to early leaf spot disease resistance through selective genotyping and single marker analysis in groundnut (Arachis hypogaea L.)

Groundnut (Arachis hypogaea L.) is an important oilseed and food crop of the world. Breeding for disease resistance is one of major objectives in groundnut breeding. Early leaf spot (ELS) is one of the major destructive diseases worldwide and in West Africa, particularly in Burkina Faso causing significant yield losses. Conventional breeding approaches have been employed to develop improved varieties resistant to ELS. Molecular dissection of resistance traits using QTL analysis can improve the efficiency of resistance breeding. In the present study, an ELS susceptible genotype QH243C and an ELS resistant genotype NAMA were crossed and the F2 population genotypic and F3 progenies phenotypic data were used for marker-trait association analysis. Parents were surveyed with 179 simple sequence repeat (SSR) markers out of which 103 SSR markers were found to be polymorphic between the parents. These polymorphic markers were utilized to genotype the F2 population followed by marker-trait analysis through single marker analysis (SMA) and selective genotyping of the population using 23 resistant and 23 susceptible genotypes. The SMA revealed 13 markers while the selective genotyping method identified 8 markers associated with ELS resistance. Four markers (GM1911, GM1883, GM1000 and Seq13E09) were found common between the two trait mapping methods. These four markers could be employed in genomics-assisted breeding for selection of ELS resistant genotypes in groundnut breeding.

Characterization of small RNA populations in non-transgenic and aflatoxin-reducing-transformed peanut

Aflatoxin contamination is a major constraint in food production worldwide. In peanut (Arachis hypogaea L.), these toxic and carcinogenic aflatoxins are mainly produced by Aspergillus flavus Link and A. parasiticus Speare. The use of RNA interference (RNAi) is a promising method to reduce or prevent the accumulation of aflatoxin in peanut seed. In this study, we performed high-throughput sequencing of small RNA populations in a control line and in two transformed peanut lines that expressed an inverted repeat targeting five genes involved in the aflatoxin-biosynthesis pathway and that showed up to 100% less aflatoxin B₁ than the controls. The objective was to determine the putative involvement of the small RNA populations in aflatoxin reduction. In total, 41 known microRNA (miRNA) families and many novel miRNAs were identified. Among those, 89 known and 10 novel miRNAs were differentially expressed in the transformed lines. We furthermore found two small interfering RNAs derived from the inverted repeat, and 39 sRNAs that mapped without mismatches to the genome of A. flavus and were present only in the transformed lines. This information will increase our understanding of the effectiveness of RNAi and enable the possible improvement of the RNAi technology for the control of aflatoxins.

Effect of end of season water deficit on phenolic compounds in peanut genotypes with different levels of resistance to drought

Terminal drought reduces pod yield and affected the phenolic content of leaves, stems and seed of peanut (Arachis hypogaea L.). The aim of this study was to investigate the effects of end of season water deficit on phenolic content in drought tolerant and sensitive genotypes of peanuts. Five peanut genotypes were planted under two water regimes, field capacity and 1/3 available water. Phenolic content was analyzed in seeds, leaves, and stems. The results revealed that terminal drought decreased phenolic content in seeds of both tolerant and sensitive genotypes. Phenolic content in leaves and stems increased under terminal drought stress in both years. This study provides basic information on changes in phenolic content in several parts of peanut plants when subjected to drought stress. Future studies to define the effect of terminal drought stress on specific phenolic compounds and antioxidant properties in peanut are warranted.

Exciting journey of 10 years from genomes to fields and markets: Some success stories of genomics-assisted breeding in chickpea, pigeonpea and groundnut

Legume crops such as chickpea, pigeonpea and groundnut, mostly grown in marginal environments, are the major source of nutrition and protein to the human population in Asia and Sub-Saharan Africa. These crops, however, have a low productivity, mainly due to their exposure to several biotic and abiotic stresses in the marginal environments. Until 2005, these crops had limited genomics resources and molecular breeding was very challenging. During the last decade (2005-2015), ICRISAT led demand-driven innovations in genome science and translated the massive genome information in breeding. For instance, large-scale genomic resources including draft genome assemblies, comprehensive genetic and physical maps, thousands of SSR markers, millions of SNPs, several high-throughput as well as low cost marker genotyping platforms have been developed in these crops. After mapping several breeding related traits, several success stories of translational genomics have become available in these legumes. These include development of superior lines with enhanced drought tolerance in chickpea, enhanced and pyramided resistance to Fusarium wilt and Ascochyta blight in chickpea, enhanced resistance to leaf rust in groundnut, improved oil quality in groundnut and utilization of markers for assessing purity of hybrids/parental lines in pigeonpea. Some of these stories together with future prospects have been discussed.

Agricultural waste as a source for the production of silica nanoparticles

The major interest of the paper deals with the extraction of silica from four natural sources such as rice husk, bamboo leaves, sugarcane bagasse and groundnut shell. These waste materials in large quantities can create a serious environmental problem. Hence, there is a need to adopt proper strategy to reduce the waste. In the present investigation, all the waste materials are subjected to moisture removal in a hot plate and sintered at 900°C for 7 h. The sintered powder was treated with 1 M NaOH to form sodium silicate and then with 6M H2SO4 to precipitate silica. The prepared silica powders were characterized by FT-IR, XRD and SEM-EDAX analysis. The silica recovered from different sources was found to vary between 52% and 78%. Magnesium substituted silica was formed from the groundnut waste and further treatment is required to precipitate silica.

Knowledge of aflatoxin contamination in groundnut and the risk of its ingestion among health workers in Ibadan, Nigeria

OBJECTIVE

To assess the awareness and knowledge of aflatoxin contamination in groundnut and the risk of its ingestion among health workers in Ibadan.

METHODS

The study was a descriptive cross-sectional study. Study instrument was a semi-structured self administered questionnaire. The respondents were health workers from a public health facility.

RESULTS

A total of 417 health workers participated out of which males were 60.2%. The mean age of respondents was (28.0±4.9)years old. Doctors made up 83.0% while others were nurses. 95% of the respondents had previous awareness of aflatoxin and class room lectures was the most common source of information (56%). Occupation and religion both showed a significant association with previous awareness of aflatoxin (P<0.05). Knowledge regarding aflatoxin contamination in groundnut and the risk of its ingestion was obtained showing knowledge score range of 0 to 14. In all, 80.6% had good scores of 11 to 14. None of the respondents had ever told their patients about the risk of aflatoxin ingestion.

CONCLUSIONS

There is a need to explore the possibility of incorporating aflatoxin awareness into routine health talk to increase the level of awareness of patients and their relatives.

Transport via xylem and accumulation of aflatoxin in seeds of groundnut plant

Aflatoxin contamination in groundnut seeds in the absence of any aflatoxigenic fungi leads to a hypothesis that aflatoxins are present naturally in soil and is transferred to seeds through uptake by roots. A survey was conducted on the natural occurrence of aflatoxins in agricultural soils, among nine main groundnut-growing regions of Karnataka state, India. All 71 soil samples collected in this survey were contaminated with aflatoxins esp. AFB1. An in vitro xylem sap experiment proved the ability of groundnut plant roots to absorb AFB1, and transport to aerial plant parts via the xylem. Hydroponics experiment also proved the uptake of AFB1 by the roots and their translocation to shoot. Uptake was affected by the initial concentration of toxin and pH of the medium. Among the 14 varieties screened, GPBD4 and MLT.K.107 (III) recorded highest and least AFB1 uptake, respectively. The above results were validated using a greenhouse experiment. Here, the aflatoxin absorbed by root gradually transferred to shoot that was later found in seeds towards the end of experiment. Thus, the groundnut seeds can also get contaminated with aflatoxin by direct uptake of aflatoxin through conducting tissue in addition to fungal infection. The present study revealed the novel mode of aflatoxin contamination in groundnut seeds without fungal infection.

Ectopic over-expression of peroxisomal ascorbate peroxidase (SbpAPX) gene confers salt stress tolerance in transgenic peanut (Arachis hypogaea)

Peroxisomal ascorbate peroxidase gene (SbpAPX) of an extreme halophyte Salicornia brachiata imparts abiotic stress endurance and plays a key role in the protection against oxidative stress. The cloned SbpAPX gene was transformed to local variety of peanut and about 100 transgenic plants were developed using optimized in vitro regeneration and Agrobacterium mediated genetic transformation method. The T0 transgenic plants were confirmed for the gene integration; grown under controlled condition in containment green house facility; seeds were harvested and T1 plants were raised. Transgenic plants (T1) were further confirmed by PCR using gene specific primers and histochemical GUS assay. About 40 transgenic plants (T1) were selected randomly and subjected for salt stress tolerance study. Transgenic plants remained green however non-transgenic plants showed bleaching and yellowish leaves under salt stress conditions. Under stress condition, transgenic plants continued normal growth and completed their life cycle. Transgenic peanut plants exhibited adequate tolerance under salt stress condition and thus could be explored for the cultivation in salt affected areas for the sustainable agriculture.

(22)Na influx is significantly lower in salt tolerant groundnut (Arachis hypogaea) varieties

Distinct varieties differing in salt tolerance were initially identified from two separate green house experiments using two systems; solution as well as soil culture. The first screening involved a diverse group of 27 cultivars. Several physiological traits; Chlorophyll Stability Index (CSI), Salt Tolerance Index (STI) and ion content were determined to screen the cultivars for differences in salt tolerance using solution culture in the first experiment. A set of six varieties (three tolerant and three susceptible) were selected from this experiment and then subjected again to salt stress adopting a natural soil system in the second experiment which involved a screening approach essentially similar to that of the first experiment. In the third experiment using two distinct cultivars differing in salt tolerance selected from experiment II, (22)Na influx rate was determined in the root and shoot at the end of a 24 h salt imposition in Hoagland's nutrient system containing 180 KBq of (22)Na. The results suggested that there were distinct differences in (22)Na influx rate into root and concurrently in the shoot. The salt tolerant Spanish improved and one of the moderately tolerant Trombay variety TAG 24, showed good regulation of (22)Na influx resulting in low (22)Na concentration. The salt susceptible variety JSP39 had nearly 7-8 fold higher root (22)Na content as compared to the tolerant and moderately tolerant cultivars. The results have highlighted the importance of Na exclusion as an important determinant of salt tolerance in groundnut.

Transgenics in groundnut (Arachis hypogaea L.) expressing cry1AcF gene for resistance to Spodoptera litura (F.)

Large number of primary transgenic events were generated in groundnut by an Agrobacterium mediated, in planta transformation method to assess the efficacy of cry1AcF against the Spodoptera litura. The amplification of required size fragment of 750 bp with npt II primers and 901 bp with cry1AcF gene primers confirmed the integration of the gene. The expression of the cry gene was ascertained by ELISA in T2 generation, and the maximum concentration of cry protein in transgenic plants reached approximately 0.82 μg/g FW. Further, Southern blot analysis of ten T2 transgenic plants proved that transgene had been integrated in the genome of all the plants and Northern analysis of the same plants demonstrated the active expression of cry1AcF gene. The highest mean % larval mortalities 80.0 and 85.0 with an average mean % larval mortalities 16.25 (n = 369) and 26.0 (n = 80) were recorded in T1 and T2 generations, respectively. Segregation analysis of the selected lines in the T3 generation demonstrated homozygous nature. This clearly proved that though there is considerable improvement in average mean % larval mortality in T2 generation, the cry1AcF gene was effective against S. litura only to some extent.

Production of Exo-polysaccharide by Rhizobium sp

Two fold increase in the yield of glucose and maltose containing exo-polysaccharide (EPS) by Rhizobium sp. was observed during its growth in modified YEMB. EPS production, plant growth promotion activity and root colonization of Rhizobium sp. studies showed enhanced EPS synthesis, more seed germination and over all improvement in plant growth over control and R. meliloti treatment. Groundnut seeds bacterized with Rhizobium sp. resulted in 69.75% more root length, 49.51% more shoot height, 13.75% more number of branches and 13.60% more number of pods over the control and R. meliloti treatment. Bacterization of wheat seeds increased the dry matter yield of roots (1.7-fold), and roots adhering soil (RAS) (1.5) and shoot mass (1.9-fold). Rhizobium sp. inoculation also increased the population density of EPS-producing bacteria on the rhizoplane. Roots of plants inoculated with Rhizobium sp. maintained a higher K(+)/Na(+) ratio and K(+)-Na(+) selectivity.

New Experimental Hosts of Tobacco streak virus and Absence of True Seed Transmission in Leguminous Hosts

Of 70 plant species tested, 50 species were susceptible to Tobacco streak virus (TSV) on sap inoculation. Both localized (necrotic and chlorotic spots) and systemic (necrotic spots, axillary shoot proliferation, stunting, total necrosis and wilt) symptoms are observed by majority of plant species. Eleven new experimental hosts were identified viz., Amaranthus blitum var. oleracea (Chaulai sag), Celosia cristata (Cocks comb), Beta vulgaris var. bengalensis (Palak/Indian spinach), Calendula officinalis (Pot marigold), Chrysanthemum indicum, Cosmos sulphurens (Yellow cosmos), Citrullus lunatus (Watermelon), Lagenaria siceraria (Bottle gourd), Coriandrum sativum (Coriander), Hibiscus subderiffa var. subderiffa (Roselle) and Portulaca oleraceae (Little hogweed). Detected groundnut seed infection with TSV for the first time by Direct antigen coated immunosorbent assay (DAC-ELISA) using whole seed. The seed infection ranged from 18.9 to 28.9% among the seeds collected from naturally infected and sap inoculated groundnut varieties (JL 24, TMV 2, Prasuna, Kadiri 6, Kadiri 9, Anantha and Kadiri 7 Bold) belonging to spanish and virginia types. Further, TSV was detected both in pod shell and seed testa and none of the samples showed the presence of TSV either in cotyledon or embryo. Grow-out and bio-assay tests proved the absence of seed transmission in groundnut and other legume crops. Hence, TSV isolate was not a true seed transmission case under Indian conditions in legumes.

In vitro regeneration via caulogenesis and brassin-induced shoot conversion of dormant buds from plumular explants of peanut (Arachis hypogaea L. cv `Okrun')

Shoot buds were induced from plumular explants of peanut (Arachis hypogaea L., cv `Okrun') preconditioned on medium containing 2,4-dichlorophenoxyacetic acid and kinetin and then transferred to regeneration medium containing benzylaminopurine and β-naphthoxyacetic acid. Buds differentiated 25 days following transfer to regeneration medium. Each explant produced 30 to 40 buds, but only 4 shoots. The remaining buds were dormant and did not produce shoots when maintained on regeneration medium. Shoots were regenerated continuously, however, when explants were subsequently transferred to shoot conversion medium containing 1 µM brassin, benzylaminopurine and β-naphthoxyacetic acid, respectively. Approximately 5 shoots were harvested every 30 days after transfer to shoot conversion medium for up to 7 months. No further shoot production was observed from explants maintained on regeneration medium without brassin. Regenerated shoots could be rooted and produced viable seeds. This procedure provides an efficient and reliable system for regeneration and transformation studies using cv `Okrun'.