Diseases Of Groundnut Research Articles

Genetic analysis of resistance to late leaf spot in interspecific groundnuts

Late leaf spot (LLS), caused by Phaeoisariopsis personata, is an important foliar fungal disease of groundnut (Arachis hypogaea L.), which causes significant economic losses globally to the crop. Inheritance of resistance to LLS disease was studied in three crosses and their reciprocals involving two resistant interspecific derivatives and a susceptible cultivar to refine strategy for LLS resistance breeding. The traits associated with LLS resistance, measured both in the field and under controlled conditions were studied following generation mean analysis. Results suggested that resistance to LLS is controlled by a combination of both, nuclear and maternal gene effects. Among nuclear gene effects, additive effect controlled majority of the variation. In JL 24 × ICG 11337 cross and its reciprocal only additive effects were important, while in JL 24 × ICG 13919 cross and its reciprocal, both additive and dominance effects contributed to the variation. Among digenic epistatic effects, additive × dominance interactions were significant. Additive–maternal effects were significant in both the crosses, while dominance–maternal effects also contributed to the variation in the crosses between the parents, JL 24 and ICG 13919. Due to significant contribution of additive effects of both nuclear and maternal inheritance to resistance to LLS, the parent, ICG 11337 would be a good donor in breeding programs. It would be worthwhile to use the resistance donor as female parent to tap maternal effects of resistance to LLS. Disease score is the best selection criterion in the field for use in breeding programs because of its high heritability and ease in measurement.

Advances in genetics and molecular breeding of three legume crops of semi-arid tropics using next-generation sequencing and high-throughput genotyping technologies

Molecular markers are the most powerful genomic tools to increase the efficiency and precision of breeding practices for crop improvement. Progress in the development of genomic resources in the leading legume crops of the semi-arid tropics (SAT), namely, chickpea (Cicer arietinum), pigeonpea (Cajanus cajan) and groundnut (Arachis hypogaea), as compared to other crop species like cereals, has been very slow. With the advances in next-generation sequencing (NGS) and high-throughput (HTP) genotyping methods, there is a shift in development of genomic resources including molecular markers in these crops. For instance, 2,000 to 3,000 novel simple sequence repeats (SSR) markers have been developed each for chickpea, pigeonpea and groundnut. Based on Sanger, 454/FLX and Illumina transcript reads, transcriptome assemblies have been developed for chickpea (44,845 transcript assembly contigs, or TACs) and pigeonpea (21,434 TACs). Illumina sequencing of some parental genotypes of mapping populations has resulted in the development of 120 million reads for chickpea and 128.9 million reads for pigeonpea. Alignment of these Illumina reads with respective transcriptome assemblies have provided more than 10,000 SNPs each in chickpea and pigeonpea. A variety of SNP genotyping platforms including GoldenGate, VeraCode and Competitive Allele Specific PCR (KASPar) assays have been developed in chickpea and pigeonpea. By using above resources, the first-generation or comprehensive genetic maps have been developed in the three legume speciesmentioned above. Analysis of phenotyping data together with genotyping data has provided candidate markers for drought-tolerance-related root traits in chickpea, resistance to foliar diseases in groundnut and sterility mosaic disease (SMD) and fertility restoration in pigeonpea. Together with these traitassociated markers along with those already available, molecular breeding programmes have been initiated for enhancing drought tolerance, resistance to fusarium wilt and ascochyta blight in chickpea and resistance to foliar diseases in groundnut. These trait-associated robust markers along with other genomic resources including genetic maps and genomic resources will certainly accelerate crop improvement programmes in the SAT legumes.

Management of root rot disease of groundnut (Arachis hypogeae L.) by plant extracts

A field experiment was conducted during 2009 to 2010 crop season in district Chakwal to evaluate the efficiency of aqueous extracts of five plant species, namely Allium cepa L. (onion), Allium sativum L. (garlic), Boerhaavia diffusa auct. Plur., Calotropis procera (Aiton) W.T. Aiton., Cannabis sativa L., and two fungicide antracol and ridomil and both fungicides in mixture form, to manage the root rot disease of groundnut (Arachis hypogeae L.) caused by a fungal pathogen Fusarium solani (Mart) Sacc. Fusarium inoculation showed 98% disease incidence with 22% mortality. Recommended dose of the chemical fungicides antracol and ridomil significantly reduced the disease incidence to 17 and 18%, respectively and mortality to 10% each separately. Fungicides in mixture form reduced the disease and mortality to 10 and 7%, respectively. Plant extract treatments exhibited variable effects on the incidence of the disease and mortality of plants. In general, all the test plant extracts managed the root rot disease to varying degrees. Aqueous bulb extracts of A. sativum andA. cepa and the leaf extract of C. procera showed better disease management potential than that of the recommended doses of antracol and ridomil. Fusarium inoculation significantly declined plant growth. In general, antracol and ridomil, as well as aqueous extracts, enhanced plant growth to variable degrees as compared to the Fusarium control. Key words: Root rot, Fusarium solani, groundnut, plant extracts.

Survey of root rot of groundnut in rainfed areas of Punjab, Pakistan

To monitor root rot disease of groundnut, a survey was carried in the groundnut growing areas of Attock, Chakwal, Khushab, Mianwali and Rawalpindi districts of Punjab during September and October, 2008. To assess prevalence, incidence and severity of root rot, soil and plant samples were collected from 52 locations of the earlier-mentioned districts of Punjab. The highest mean root rot incidence (63%) was observed in Attock, whereas the lowest (0%) was observed in Khushab. The highest mean severity was 2.5 in Attock, while the lowest (1.3) was in Chakwal. Aspergillus spp., Alternaria sp., Curvularia sp., Fusarium spp., Phoma sp., Rhizopus spp. and Penicillium spp., were isolated from soil and root, stem and foliar samples of plants showing root rot symptoms. During this survey, it was concluded that root rot causes significant losses in the groundnut crop.

Epidemiology of the Groundnut (<i>Arachis hypogaea</i> L.) Leaf Spot Disease: Genetic Analysis and Developmental Cycles

Groundnut leaf spot is one of the important factors limiting groundnut productivity in Africa particularly in the Democratic Republic of Congo (DR Congo). Early and late leaf spot disease of groundnut caused by Cercospora arachidicola Hori and Cercosporidium personatum (Berk & Curt.) Deighton, respectively, can cause considerable yield losses without fungicide management. The main objectives of this research were to analyze plant and disease developmental cycles. Significant differences were observed among the groundnut varieties evaluated for resistance to the leaf spot disease. The results show that plant development cycle can be divided into three developmental stages. A first stage characterized by a low production of leaves, a second stage with a significant leaf development and finally a third stage with a reduction of leaves. Interestingly, the leaf spot disease cycle was also divided in three stages. The disease stage characterized by the highest level of symptom expression was not associated with the plant phase with the highest emerged leaves. Disease symptoms reached the highest pick only after the phase of intense leaf development. The molecular analysis revealed that all the groundnut varieties analyzed were genetically closely related even though they showed different reactions to the leaf spot disease.

Involvement of phenazines and lipopeptides in interactions between Pseudomonas species and Sclerotium rolfsii, causal agent of stem rot disease on groundnut

To determine the role of phenazines (PHZ) and lipopeptide surfactants (LPs) produced by Pseudomonas in suppression of stem rot disease of groundnut, caused by the fungal pathogen Sclerotium rolfsii. In vitro assays showed that PHZ-producing Pseudomonas chlororaphis strain Phz24 significantly inhibited hyphal growth of S. rolfsii and suppressed stem rot disease of groundnut under field conditions. Biosynthesis and regulatory mutants of Phz24 deficient in PHZ production were less effective in pathogen suppression. Pseudomonas strains SS101, SBW25 and 267, producing viscosin or putisolvin-like LPs, only marginally inhibited hyphal growth of S. rolfsii and did not suppress stem rot disease. In contrast, Pseudomonas strain SH-C52, producing the chlorinated LP thanamycin, inhibited hyphal growth of S. rolfsii and significantly reduced stem rot disease of groundnut in nethouse and field experiments, whereas its thanamycin-deficient mutant was less effective. Phenazines and specific lipopeptides play an important role in suppression of stem rot disease of groundnut by root-colonizing Pseudomonas strains. Pseudomonas strains Phz24 and SH-C52 showed significant control of stem rot disease. Treatment of seeds or soil with these strains provides a promising supplementary strategy to control stem rot disease of groundnut.

Efficacy of Trichoderma harzianum and Verticillium lecanii against stem rot, collar rot and foliar fungal diseases of groundnut

A field experiment was conducted to find the efficacy of Trichoderma harzianum isolate DGR T-170 and V. lecanii isolate DGR V-1 for the management of soil borne diseases (stem rot, collar rot and afla rot) and foliar diseases (early leaf spot, late leaf rot and rust) of groundnut during Kharif season for two consecutive years (2009 to 2010). Per cent incidence of soil borne diseases was found highly suppressed in the treatment that included foliar spray of T. harzianum spore suspension @ 1.5 × 10 6 cfu/ml as 3 sprays starting from 1st appearance of disease and subsequent spray at 15 days interval (1.75, 2.59 and 1.03 respectively) and in another treatment that included foliar application of T. harzianum culture filtrate diluted as 50% (2.63, 2.50 and 0.66 respectively) compared to control (5.12, 5.03 and 5.38, respectively). The disease severity of foliar diseases was recorded lowest in the treatment that included foliar application of Trichoderma culture filtrate diluted as 50% (5.33, 4.22 and 3.56 respectively), and in another treatment that included foliar application of culture filtrate of V. lecanii diluted as 50% in two sprays at 15 days interval, 1 st spray at appearance of diseases and 2 nd spray after 15 days of 1 st spray (5.44, 3.89 and 3.67 respectively) followed by the treatment that included soil application of castor cake @ 500kg/ha + foliar application of culture filtrate of V. lecanii at 50% dilution (5.44, 4.00 and 3.22 respectively) compared to control (8.00, 7.49 and 6.56 respectively).

Effects of Variety and Fungicidal Rate on <i>Cercospora</i> Leaf Spots Disease of Groundnut in the Sudan Savanna

A field study was carried out at the University of Maiduguri Teaching and Research Farm during the 2006, 2007 and 2008 cropping seasons to evaluate the effects of variety and fungicidal rate on Cercospora leaf spot disease of groundnut. The experimental design used was Randomized Complete Block Design (RCBD) with twelve treatment combinations of three varieties of groundnut (Ex-Dakar, RRB and ICGV-86024) and four levels of fungicidal rate (0, 1, 2 and 4 kgha¡¥1 of fungicide mancozeb) replicated three times. Disease incidence and disease severity were significantly higher in Ex-Dakar and 0 kgha¡¥1, thus had lower yields. Higher seed and haulm yield were recorded by RRB, ICGV-86024, as well as 2 and 4 kgha¡¥1 as a result of lower disease incidence and severity.

Web Blotch Disease of Groundnut (<i>Arachis hypogaea</i>) in Nsukka

Web blotch diseases of groundnut were observed in groundnut farms in Nsukka on the Spanish groundnut cultivars. The disease was characterized by tan-coloured web like blotches on infected leaves. Blotches have grayish irregular margins and lower leaves were affected while new leaves were rarely attacked. The fungus in culture showed a creamy white mycelial growth that became black or dark brown within two weeks when it produced abundant chlamydospores in chains. Pycnidia of the fungus were observed on leave tissues when the leaves were maintained in moist environment within four weeks. The organism is called Phoma sorghina and confirmed by International Mycological Society in Kew, England (IMI number 368112). The best type of inoculum of the organism was a two weeks old culture since it produces the best lesion than other sources of inoculum (9.5 ± 0.94). It also induces the highest leaf abscission (5.1 ± 1.9).The more the inoculum the higher the disease incidence (9.6 ± 0.94) at 105spores. Two weeks old inoculum was also the best at inducing lesions (11.30 ± .80) as well as inducing defoliation (5.5 ± 0.92). Keywords: Web blotch diseases, Groundnut, Chlamydospores, Phoma sorghina inoculum

Molecular tagging of a rust resistance gene in cultivated groundnut (Arachis hypogaea L.) introgressed from Arachis cardenasii

Rust is a serious and the most prevalent groundnut disease in tropical and subtropical growing regions of the world. A total of 164 recombinant inbred lines derived from resistant (VG 9514) and susceptible (TAG 24) cultivated groundnut parents were screened for rust resistance in five environments. Subsequent genotyping of these lines with 109 simple sequence repeat (SSR) markers generated a genetic linkage map with 24 linkage groups. The total length of the linkage map was 882.9 cM with an average of 9.0 cM between neighbouring markers. The markers pPGPseq4A05 and gi56931710 flanked the rust resistance gene at map distances of 4.7 cM and 4.3 cM, respectively, in linkage group 2. The significant association of these two markers with the rust reaction was also confirmed by discriminant analysis. The informative SSR markers classified rust-resistant and susceptible groups with 99.97% correctness. The SSR markers pPGPseq4A05 and gi56931710 were able to identify all the susceptible genotypes from a set of 20 cultivated genotypes differing in rust reaction. Tagging of the rust resistance locus with linked SSR markers will be useful in selecting the rust resistant genotypes from segregating populations and in introgressing the rust resistance genes from diploid wild species.

A QTL study on late leaf spot and rust revealed one major QTL for molecular breeding for rust resistance in groundnut (Arachis hypogaea L.)

Late leaf spot (LLS) and rust are two major foliar diseases of groundnut (Arachis hypogaea L.) that often occur together leading to 50–70% yield loss in the crop. A total of 268 recombinant inbred lines of a mapping population TAG 24 × GPBD 4 segregating for LLS and rust were used to undertake quantitative trait locus (QTL) analysis. Phenotyping of the population was carried out under artificial disease epiphytotics. Positive correlations between different stages, high to very high heritability and independent nature of inheritance between both the diseases were observed. Parental genotypes were screened with 1,089 simple sequence repeat (SSR) markers, of which 67 (6.15%) were found polymorphic. Segregation data obtained for these markers facilitated development of partial linkage map (14 linkage groups) with 56 SSR loci. Composite interval mapping (CIM) undertaken on genotyping and phenotyping data yielded 11 QTLs for LLS (explaining 1.70–6.50% phenotypic variation) in three environments and 12 QTLs for rust (explaining 1.70–55.20% phenotypic variation). Interestingly a major QTL associated with rust (QTLrust01), contributing 6.90–55.20% variation, was identified by both CIM and single marker analysis (SMA). A candidate SSR marker (IPAHM 103) linked with this QTL was validated using a wide range of resistant/susceptible breeding lines as well as progeny lines of another mapping population (TG 26 × GPBD 4). Therefore, this marker should be useful for introgressing the major QTL for rust in desired lines/varieties of groundnut through marker-assisted backcrossing.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-010-1366-x) contains supplementary material, which is available to authorized users.

Varietal Differences on Incidence and Severity of Leafspot Disease of Groundnut

Groundnut (Arachis hypogaea) is a well known oil-seed crop grown mostly in the savannah areas of Nigeria, andwith little cultivation in the forest south. Groundnut comprise of two widely used varieties. The spreading type ismore modulated than the erect. Groundnut is affected by diseases such as fungal, viruses and bacterial diseases.The two principal species of fungal leafspot diseases being the Cercospora arichidicola which cause early leafspot andCercosporidum personatum which cause late leafspot. These are distinguished by the size and shape of the conidiaand the number of Septa. Analysis shows a significant difference in leafspot disease severity at 8 weeks of plantage, leaf area production at 6 and 10 weeks of plant age, Biomass, Pod length, Pod size index and 10-pods weightalthough there is no significant difference on plant depth in the two varieties. Plant densities recorded a significantdifference on the severity of leafspot diseases at 4, 8 and 12 weeks on early maturing variety but the leaf maturingonly showed a significant difference of 12 weeks of plant age. Interaction of plant depth and density are significantin the two varieties but early maturing is significant, in plant height at 4 and 10 weeks. Erect type recorded lowerdisease severity and percentage defoliation of 0.8 and 76.3% while spreading type (late maturing) 0.82 and 89.6%were high.

Prophylactic effect of paw-paw and better leave extracts on the severity of foliar fungal disease of groundnut (<i>Arachis hypogaea </i> L.) in Ishiagu, Southeast Nigeria

Prophylactic effect of paw-paw and better leave extracts on the severity of foliar fungal disease of groundnut (<i>Arachis hypogaea </i> L.) in Ishiagu, Southeast Nigeria

Levels of variability in groundnut (Arachis hypogaea L.) to cercospora leaf spot disease implication for selection

Groundnut (Arachis hypogaea L.) is an important crop both in subsistence and commercial agriculture in arid and semi-arid regions of the world. Leaf spot diseases caused by fungus have been a major destructive disease of groundnut and could cause a yield loss of up to 50 % or more. A two-year experiment was conducted during the cropping seasons of 2002 and 2003 at the Faculty of Agriculture Research Farm, University of Maiduguri, Nigeria. The objective of the study was to determine the reaction of different groundnut varieties to cercospora leaf spot disease to create basis for selection for cercospora leaf spot disease tolerance. The experiment consisted of twenty-four groundnut varieties, laid out in a randomized complete block design (RCBD) with three replications. The analysis of variance (ANOVA) indicated highly significant difference among the groundnut varieties in all the characters studied. The results indicated that ICGV-SM-93531, ICGV-IS-96802, ICGV-IS-96827 and ICGV-IS-96808 had the lowest cercospora leaf spot incidence. The variety ICGV-IS-96808 that produced the highest kernel yield also had the lowest days to 50% flowering and incidentally is among varieties that recorded the lowest leaf spot incidence. The study found tremendous level of variability existing among the groundnut varieties that is essential in crop improvement. This study recommends that development or selection of tolerant varieties to leaf spot should be based on their level of incidence. This will be the only effective measure in decreasing production costs and protect the environment from pollution. Potential therefore exist for selection among the groundnut varieties evaluated for cercospora leaf spot disease tolerance. There is however, a need to undertake further studies in order to determine the type and the number of genes controlling cercospora leaf spot disease tolerance in groundnuts for enhanced breeding strategies.

Effects of Maize Intercropping on Incidence and Severity of Leafspot Disease (Cercospora arachidicola Hori) and Nodulation of Groundnut

A two seasons experiment conducted in 1999 and 2000 planting seasons, respectively to determine the effects of maize intercropping and plant density on the incidence and severity of Cercosporo arachidicola Hori and nodulation of groundnut. Investigation revealed that groundnut intercropped with maize was highly significant on incidence and severity of Cercospora arachidicola Hori leafspot disease of groundnut at 0.05 probability level. Intercropping showed a significantly lower leaspot disease severity 0.6.4 and 0.76 and a lower nodulation of 86.4 and 87.0% in 1999 and 2000, respectively in comparison with sole groundnut 0.77 and 0.86 leafspot disease severity and 88.5 and 98% defoliation in 1999 and 2000, respectively. Plant density 250,000 plants ha-1 recorded 0.00 incidence of leafspot disease at 4 weeks of plant age in both seasons, as well as least severity of leafspot disease 0.30 and 0.35 but high nodulation of 14.75 and 13.95 in 1999 and 2000, respectively while 1,000,000 plants ha-1 had highest severity 1.15 and 1.24 but low nodulation 12.63 and 11.05 in 1999 and 2000, respectively. There is also a direct relation on severity of leafspot disease with age of groundnut planted in both seasons. Groundnut intercropped with maize had significantly high nodulation 12.44 and 13.05 when sole groundnut 11.31 and 11.55 in 1999 and 2000, respectively were low

Effects of Plant Extracts and Plant Density on the Severity of Leafspot Disease of Groundnut (Cercospora arachidicola. Hori) in Imo State

Effects of Plant Extracts and Plant Density on the Severity of Leafspot Disease of Groundnut (Cercospora arachidicola. Hori) in Imo State

Role of Fluorescent Pseudomonads in Plant Growth Promotion and Biological Control of Late Leaf Spot of Groundnut

Twenty strains of Pseudomonas fluorescens were evaluated for their potential in promoting plant growth and in the control of late leaf spot caused by Cercosporidium personatum in groundnut under greenhouse conditions. Seed treatment with P. fluorescens strain Pf1 recorded the highest germination percentage and the maximum plant height. Seed treatment with P. fluorescens Pf1 significantly controlled late leaf spot disease of groundnut and increased the pod yield. When the treated seeds were sown in soil, the antagonist colonized well in the groundnut rhizosphere. P. fluorescens Pf1 showed the maximum production of indole acetic acid in in vitro.

Influence of variety and intra-row spacing on <i>Cercospora</i> leafspot disease of groundnut in Bauchi, Nigeria

Cercospora leafspot infection was analyzed for ten diverse groundnut varieties sown at two intra-row spacings during 1998 and 1999 rainy seasons at Bauchi, Nigeria. Significantly (P Cercospora leafspot were obtained at 50x30cm intra-row spacing. Spacing of 50x20cm however encouraged development of the disease. Late maturing and spreading types were resistant to Cercospora leafspot,compared to erect and early maturing types which are susceptible. Progress of Cercospora leafspot on groundnut was influenced by higher rainfall, relative humidity and low temperatures. Global Journal of Agricultural Sciences Vol. 4(2) 2005: 177-182

Integrated management of late leaf spot and rust diseases of groundnut (Arachis hypogaea L.) with Prosopis juliflora leaf extract and chlorothalonil

Late leaf spot (LLS, Phaeoisariopsis personata) and rust (Puccinia arachidis) are the two major biotic constraints of groundnut (Arachis hypogaea L.) of global importance. To identify economic and eco-friendly disease management options, we evaluated extracts of 38 plant spp. of 23 families, for their antifungal activity. Aqueous leaf extracts (20%, w/v) of Prosopis juliflora and Lycopersicon esculentum completely inhibited the in vitro germination of P. personata and P. arachidis, and extracts of Achras sapota, Cyamposis tetragonolobus, Piper betle and Tagetus patula were inhibitory by >95%. In the greenhouse, the severity of LLS and rust corresponded with the time interval between the foliar application of leaf extract and fungal inoculum. Extract of P. juliflora (2%, w/v) in simultaneous application reduced the lesion frequency of LLS and rust by ∼75%, and 35.7% and 50.7% in a prophylactic spray of 96 h before the pathogen inoculation. The extract had no effect on the phenolic content of groundnut leaves both during LLS and rust infections. In the field, P. juliflora extract applied four times at 15-day intervals, was effective against LLS and rust up to 95 days after sowing (d.a.s.). Foliar application of P. juliflora extract at 45, 75 and 90 d.a.s. and chlorothalonil at 60 d.a.s. effectively reduced foliar diseases severity and increased the pod yields by 81–98%. This study identified P. juliflora extract as a significant component for the integrated management of groundnut foliar diseases.

Biological Control of Late Leaf Spot of Peanut (Arachis hypogaea) with Chitinolytic Bacteria

ABSTRACT Late leaf spot (LLS), caused by Phaeoisariopsis personata, is a foliar disease of groundnut or peanut (Arachis hypogaea) with high economic and global importance. Antifungal and chitinolytic Bacillus circulans GRS 243 and Serratia marcescens GPS 5, selected among a collection of 393 peanut-associated bacteria, were applied as a prophylactic foliar spray and tested for control of LLS. Chitin-supplemented application of B. circulans GRS 243 and S. marcescens GPS 5 resulted in improved biological control of LLS disease. Supplementation of bacterial cells with 1% (wt/vol) colloidal chitin reduced lesion frequency by 60% compared with application of bacterial cells alone, in the greenhouse. Chitinsupplemented application of GRS 243 and GPS 5 also resulted in improved and stable control of LLS in a repeated field experiment and increased the pod yields by 62 and 75%, respectively, compared with the control. Chitin-supplemented application of GPS 5 was tested in six onfarm trials, and the increase in pod yields was up to 48% in kharif (rainy season). A 55-kDa chitinase was purified from the cell-free culture filtrate of GPS 5 by affinity chromatography and gel filtration. Purified chitinase of S. marcescens GPS 5 (specific activity 120 units) inhibited the in vitro germination of P. personata conidia, lysed the conidia, and effectively controlled LLS in greenhouse tests, indicating the importance of chitinolysis in biological control of LLS disease by GPS 5.