Puccinia Arachidis Research Articles

Evaluation of Biocontrol-based Formulations against Late Leaf Spot and Rust in Groundnut

This study investigated the efficacy of various biocontrol-based formulations against late leaf spot (LLS) (Phaeoisariopsis personata) and rust (Puccinia arachidis) in groundnut. Pot culture and field experiments were conducted during the Kharif season (June-September) of 2022. Disease incidence of both late leaf spot and rust was significantly lower in groundnut plants treated with a combination of biocontrol-based formulations compared to control. The most effective eco-friendly treatment included a combination of Trichoderma asperellum, Pseudomonas fluorescens, fortified lignite fly ash and Annamalai mixture. This combination significantly reduced lesion frequency and Percent Disease Index (PDI) for both diseases at 50, 70 and 90 DAS, compared to other treatments. The combination of biocontrol-based formulations also significantly increased the pod yield. Furthermore, the same treatment increased the induction of defense enzymes peroxidase (2.22 fold), polyphenol oxidase (1.28 fold) and phenylalanine ammonia-lyase (6.25 fold). While Carbendazim effectively reduced disease incidence, it was surpassed by the biocontrol-based module in terms of both disease control and yield. These findings suggest that biocontrol-based formulations can be a sustainable approach for managing LLS and rust diseases in groundnut cultivation.

Sensor-Based Quantification of Peanut Disease Defoliation Using an Unmanned Aircraft System and Multispectral Imagery.

Early leaf spot (Passalora arachidicola) and late leaf spot (Nothopassalora personata) are two of the most economically important foliar fungal diseases of peanut, often requiring seven to eight fungicide applications to protect against defoliation and yield loss. Rust (Puccinia arachidis) may also cause significant defoliation depending on season and location. Sensor technologies are increasingly being utilized to objectively monitor plant disease epidemics for research and supporting integrated management decisions. This study aimed to develop an algorithm to quantify peanut disease defoliation using multispectral imagery captured by an unmanned aircraft system. The algorithm combined the Green Normalized Difference Vegetation Index and the Modified Soil-Adjusted Vegetation Index and included calibration to site-specific peak canopy growth. Beta regression was used to train a model for percent net defoliation with observed visual estimations of the variety 'GA-06G' (0 to 95%) as the target and imagery as the predictor (train: pseudo-R2 = 0.71, test k-fold cross-validation: R2 = 0.84 and RMSE = 4.0%). The model performed well on new data from two field trials not included in model training that compared 25 (R2 = 0.79, RMSE = 3.7%) and seven (R2 = 0.87, RMSE = 9.4%) fungicide programs. This objective method of assessing mid-to-late season disease severity can be used to assist growers with harvest decisions and researchers with reproducible assessment of field experiments. This model will be integrated into future work with proximal ground sensors for pathogen identification and early season disease detection.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Effects of Peanut Rust Disease (Puccinia arachidis Speg.) on Agricultural Production: Current Control Strategies and Progress in Breeding for Resistance.

Peanuts play a pivotal role as an economic crop on a global scale, serving as a primary source of both edible oil and protein. Peanut rust (Puccinia arachidis Speg.) disease constitutes a significant global biotic stress, representing a substantial economic threat to the peanut industry by inducing noteworthy reductions in seed yields and compromising oil quality. This comprehensive review delves into the distinctive characteristics and detrimental symptoms associated with peanut rust, scrutinizing its epidemiology and the control strategies that are currently implemented. Notably, host resistance emerges as the most favored strategy due to its potential to surmount the limitations inherent in other approaches. The review further considers the recent advancements in peanut rust resistance breeding, integrating the use of molecular marker technology and the identification of rust resistance genes. Our findings indicate that the ongoing refinement of control strategies, especially through the development and application of immune or highly resistant peanut varieties, will have a profound impact on the global peanut industry.

Metabolic profiles of peanut (Arachis hypogaea L.) in response to Puccinia arachidis fungal infection

Background Puccinia arachidis fungus causes rust disease in the peanut plants (Arachis hypogaea L.), which leads to high yield loss. Metabolomic profiling of Arachis hypogaea was performed to identify the pathogen-induced production of metabolites involved in the defense mechanism of peanut plants. In this study, two peanut genotypes, one susceptible (JL-24) and one resistant (GPBD-4) were inoculated with Puccinia arachidis fungal pathogen. The metabolic response was assessed at the control stage (0 day without inoculation), 2 DAI (Day after inoculation), 4 DAI and 6 DAI by Gas Chromatography-Mass Spectrometry (GC-MS). Results About 61 metabolites were identified by NIST library, comprising sugars, phenols, fatty acids, carboxylic acids and sugar alcohols. Sugars and fatty acids were predominant in leaf extracts compared to other metabolites. Concentration of different metabolites such as salicylic acid, mannitol, flavonoid, 9,12-octadecadienoic acid, linolenic acid and glucopyranoside were higher in resistant genotype than in susceptible genotype during infection. Systemic acquired resistance (SAR) and hypersensitive reaction (HR) components such as oxalic acid was elevated in resistant genotype during pathogen infection. Partial least square-discriminant analysis (PLS-DA) was applied to GC-MS data for revealing metabolites profile between resistant and susceptible genotype during infection. Conclusion The phenol content and oxidative enzyme activity i.e. catalase, peroxidase and polyphenol oxidase were found to be very high at 4 DAI in resistant genotype (p-value < 0.01). This metabolic approach provides information about bioactive plant metabolites and their application in crop protection and marker-assisted plant breeding.

BIOCONTROL OF RUST AND LEAF SPOTS DISEASES OF PEANUT USING CULTURE FILTRATES OF AKANTHOMYCESLECANIIIN NATURALCONDITIONS IN BURKINA FASO

Leaf spots and rust are the most destructive diseases of peanut in Tropical Africa, but it has shown that Akanthomyceslecanii isknown ashyperparasiteof rustandleaf spots fungi. Previous studies have investigated on the use of conidia of A.lecaniiin biocontrol of these diseases. However, the conidia are influenced by temperature and relative humidity, which could result in low efficiency of biocontrol agents in natural conditions. The use of secondary metabolites could help to fight against the plant diseases in natural conditions. Thus, we sprayed peanut plants with culture filtrates from 21-day-old cultures of two strains of A. lecanii grown in potato dextrose broth, to assess their efficiency against leaf spots and rust diseases innatural conditions. A susceptible variety SH470P and a moderately susceptible varietyPC79-79 of peanut to rust and leaf spots diseases were used. Our findings revealed that A. lecanii culture filtrates have significantly reduced the severity of rust and leaf spots diseases in SH470P only. In SH470P, the lowest severity of leaf spots in 2020 (59.26%) and 2021 (48.10%) were recorded in plots sprayed with culture filtrates of A. lecanii. The lowestseverity of rust (29.60%) was recorded in the plots sprayed with the A. lecanii culture filtrates in 2021 in SH470P. From our findings, the use of A. lecanii culture filtrates is a promising alternative in the control of peanut rust and leaf spots. But, further studies are required to determine the effective doses and active secondary metabolites against these diseases.

Mechanisms of action of Akanthomyces lecanii on peanut rust: Ultrastructural investigations

Mechanisms of action of Akanthomyces lecanii on peanut rust: Ultrastructural investigations

Early Interactions of Rust Pathogen Puccinia arachidis (Speg.) with Groundnut Genotypes Varying in Resistance

The study was conducted in the Department of Plant Pathology, College of Agriculture, Rajendranagar, Professor Jayashankar Telangana State Agricultural University, Hyderabad, India to understand the histopathological mechanisms of initial interaction of Puccinia arachidis with six groundnut genotypes. Fully expanded quadrifoliate leaves were inoculated with P. arachidis using the detached leaf assay. Five-mm leaf discs were cut at 6 hours after inoculation (hai) and each day until 5 days after inoculation (dai) and examined for histopathological interactions. Germination of urediniospores was detected during 6–8 hai and continued until 24 hai. There were no differences in pre-penetration and penetration among all the six genotypes. Differences in post-penetration were observed among the genotypes during 3–5 dai. In genotypes TMV 2 and K 6, extensive hyphal colonization was observed in the intercellular spaces of mesophyll cells by 4–5 dai indicating compatible interaction and susceptibility to rust disease. Sparse hyphal growth and corresponding mesophyll cell death at 3–5 dai in genotypes ICGV 171015 and ICGV 13229 indicated defense response by the host and moderate resistance. In genotypes ICG 11426 and GPBD 4, complete arrest of hyphal growth by 4–5 dai due to extensive mesophyll necrosis suggested incompatible interaction and resistance to rust. This is the first documentation of the histopathological description of the initial infection strategies of P. arachidis in the selected groundnut genotypes.

First report of peanut rust caused by Puccinia arachidis on Arachis hypogaea in New Caledonia

In July 2021, Arachis hypogaea (peanut) plants exhibiting typical brown rust pustules were observed in a small organic farming plot in the municipality of Païta (La Tamoa) in the Southern Province on the west coast of Grande Terre, New Caledonia (Figures 1-3). The disease affected all of the foliage, accelerating the senescence of the plants and shortening the cultivation cycle by three to four weeks. This reduced the size of the harvested peanuts by about 20–30%. Symptomatic leaves with numerous rust sori on the underside were collected and examined. The urediniospores were mostly brown, ellipsoidal, finely echinulate, variable in size (20.6–26.2 × 19.3–21.8 μm), with brown walls (1.2–1.9 μm thick) and often with two equatorial germ pores (Figure 4). No teliospores were found. Based on urediniospore morphology, the pathogen was identified tentatively as Puccinia arachidis (Mondal & Badigannavar, 2015). Puccinia arachidis is known almost exclusively by its uredinial stage. The telial stage has only been reported from Central America, Florida, and Brazil on leaves of wild peanut (Hennen et al., 1976) and more recently from cultivated peanut in India (Tashildar et al., 2012). For molecular identification, urediniospores were carefully scraped and transferred into 2 ml microtubes containing 1 mm silica beads. DNA was extracted using a commercial plant DNA extraction kit (DNeasy Plant Mini Kit, Qiagen, USA). Total DNA was diluted 10-fold and the ITS2-LSU region of the rDNA was amplified by PCR using the Rust2inv (Aime, 2006) and LR6 (Vilgalys & Hester, 1990) primers. The PCR product was sequenced and deposited in GenBank (Accession No. OM516766). BLAST analysis of the 1319 bp sequence against the whole genome sequence of P. arachidis (LBLN01000600.1) showed 100% identity, confirming the morphological identification. To our knowledge, this is the first report of Puccinia arachidis in New Caledonia. On this island, groundnuts are rarely cultivated and not extensively monitored. Nevertheless, the presence of Puccinia arachidis could have an economic impact regarding the potential development of this crop in New Caledonia since it can lead to major yield losses and may significantly reduce the pod and oil quality (Mondal & Badigannavar, 2015). Puccinia arachidis remains a quarantine pathogen in New Caledonia.

Image processing system for identifying groundnut plant disease

Groundnuts (Arachis hypogaea), also known as peanuts are the edible seeds of a legume plant that grow to maturity in the ground. Diseases and its diagnosis methodology are the main challenges to groundnut production. Manual means of identifying plant disease is the most difficult activity with a high rate of mistake and time taking procedures. Therefore, the main aim of this research was to design an image processing system to identify groundnut plant disease. In general, the major significance of the study is to provide effective and simple groundnut plant disease diagnosis system that supports disease controlling mechanism and experts in the domain area. While the process of developing the system, researchers used purposive sampling techniques for acquiring 320 sample leaves images from four classes of groundnuts plant. Those are Cercospora personatum, Cercospora arachidicola, Puccinia arachidis, and healthy leaf from Bishan-Babile and Gemechu peasant associations in Babile district, and Awdal peasant association in Gursum districts in East Hararghe zone of Oromiya Regional State. Also, the researchers conducted a survey study which helps to identify experts view and deep understanding of the domain area. The design, phase used; adaptive median filtering, K-means clustering, SVM and ANN techniques with MATLAB programming tool. In general, the overall result shows that the developed system achieved a better result with an accuracy of 90.6%.

Puccinia arachidis (groundnut leaf rust)

Puccinia arachidis (groundnut leaf rust)

Enhancing oleic acid content in two commercially released peanut varieties through marker‐assisted backcross breeding

AbstractTwo elite cultivars of peanut (Arachis hypogaea L.), GPBD 4 and G 2–52, with high productivity, oil content, resistance to late leaf spot [Phaeoisariopsis personata (Berk. &amp; Curt) V. Arx.] (LLS) and rust (Puccinia arachidis Speg.) diseases were improved for oleic acid content using marker‐assisted backcrossing. Since both the recurrent parents already possessed the mutant allele at AhFAD2A, only mutant allele at AhFAD2B was transferred from the donor ‘SunOleic 95R’ (oleate of 80.6%). Three rounds of backcrossing with foreground selection using allele‐specific polymerase chain reaction (PCR) and Kompetitive allele‐specific PCR (KASP) assay identified a large number of plants homozygous for the mutant allele at AhFAD2B in BCnF2 generations. Evaluation of the advanced generations could identify six and 10 lines with significantly higher oleate than GPBD 4 and G 2–52, respectively. Considering the yield, shelling percentage, oil, and oleate content, the most promising lines HOBC2GPS_7 and HOBC2G2S_5 were selected with 112 and 142% oleate recovery over GPBD 4 and G 2–52, respectively. Double digest restriction‐site‐associated DNA sequencing of these superior lines showed background genome recovery of 77.5 and 69.0%, respectively. These advanced breeding lines with high oleate (∼80%), resistance to LLS and rust and high productivity are under further trials for possible release as varieties for commercial cultivation.

Antimicrobial effect of crude extracts of fresh and dry leaves of Datura metel L.

Datura metel, is native of southern China is commonly called horn of plenty, devil’s trumpet, angel’s trumpet or thornapple. It is shrubby, sprawling, short-lived, tender perennial. The aim of this work is to investigate antimicrobial activities of different crude extracts from dry and fresh leaves of Datura metel. Different organic solvents including methanol, chloroform, hexane, ethyl acetate and butanol were used to prepare the crude extract from the fresh and dry leaves. Antimicrobial activities of different crude extracts from dry and fresh leaves of Datura metel were determined by DPPH method and agar agar diffusion method with minor modification. In vitro phytochemical screening for all the crude extract from both dry and fresh leaves was tested and found positive results for alkaloid, flavonoid, saponin and tannin compound. However, all the crude extract did not show positive result for steroids and triterpenoid compounds. The antioxidant activity results of both fresh and dry crude extracts show that when gradually increasing the samples concentration, there was an increase in the absorbance. Late leaf spot (LLS) (causal agent Phaeoisariopsis personata) and rust (causal agent Puccinia arachidis) are economically important foliar diseases of groundnut and have global significance. Aqueous leaf extract of Datura metel known for high antifungal activity against P. personata completely inhibited the germination of uredospores. Extracts of Datura metel (25g/L) applied as a prophylactic spray reduce the frequency of LLS lesions and rust pustules by 65-74%. In field studies, a programme of four sprays of D. metel leaf extract at 45, 60, 75 and 90 days after showing (DAS) was partially effective against the foliar diseases (LLS and rust) upto 95 DAS. The increase in pod yield by this treatment was comparable with the sustained application of chlorothalonil. Further validation of integrated applications of D. metel extract and chlorothalonil may reduce the dependency on fungicides in groundnut cultivation.

Expression of Tcchitinase-I gene in transgenic peanut (Arachis hypogaea L.) confers enhanced resistance against leaf spot and rust diseases

The disease-resistant transgenic peanut cv ICG 13942 plants were developed by using Tcchitinase-I gene. Agrobacterium tumefaciens strain LBA4404 harboring the binary vector (pBinAR) contains the chitinase (Tcchitinase-I) gene and neomycin phosphotransferase resistance (nptII) gene. The transformed shoots were developed on selection medium (MMS + 0.5 mg/L IAA + 15 mg/L TDZ + 100 mg/L Kan + 250 mg/L Cefotaxime) from deembryonated cotyledon (DC) explants. Established plantlets were screened for the presence of Tcchitinase-I and nptII genes. Stable integration and expression of the transgenes (T0) were confirmed by using PCR, RT-PCR and Southern blot analyses. The transformation frequency 63.34% was recorded. All the transformed (T0) plants were found normal, flowered and set seeds. After selfing the T0 plants, a Mendelian inheritance pattern (3:1) for the transgene in T1 progeny is revealed. T1 transgenic peanut plants were evaluated for resistance against Cercospora arachidicola, C. personatum and Puccinia arachidis by infection with the microspores using detached leaf assay. These T1 plants have shown longer incubation, latent period and lower infection frequencies in comparison to non-transformed (WT) plants. The Tcchitinase-I gene expression in resistant transgenic plants was compared to that of a susceptible control. A significant negative correlation was recorded between chitinase activity and the frequency of infection to the three tested disease causing agents.

Comparative RNA-Seq profiling of a resistant and susceptible peanut (Arachis hypogaea) genotypes in response to leaf rust infection caused by Puccinia arachidis.

The goal of this study was to identify differentially expressed genes (DEGs) responsible for peanut plant (Arachis hypogaea) defence against Puccinia arachidis (causative agent of rust disease). Genes were identified using a high-throughput RNA-sequencing strategy. In total, 86,380,930 reads were generated from RNA-Seq data of two peanut genotypes, JL-24 (susceptible), and GPBD-4 (resistant). Gene Ontology (GO) and KEGG analysis of DEGs revealed essential genes and their pathways responsible for defence response to P. arachidis. DEGs uniquely upregulated in resistant genotype included pathogenesis-related (PR) proteins, MLO such as protein, ethylene-responsive factor, thaumatin, and F-box, whereas, other genes down-regulated in susceptible genotype were Caffeate O-methyltransferase, beta-glucosidase, and transcription factors (WRKY, bZIP, MYB). Moreover, various genes, such as Chitinase, Cytochrome P450, Glutathione S-transferase, and R genes such as NBS-LRR were highly up-regulated in the resistant genotype, indicating their involvement in the plant defence mechanism. RNA-Seq analysis data were validated by RT-qPCR using 15 primer sets derived from DEGs producing high correlation value (R 2 = 0.82). A total of 4511 EST-SSRs were identified from the unigenes, which can be useful in evaluating genetic diversity among genotypes, QTL mapping, and plant variety improvement through marker-assisted breeding. These findings will help to understand the molecular defence mechanisms of the peanut plant in response to P. arachidis infection.

Evaluation of Improved Valencia Peanut Varieties for Production in Haiti

ABSTRACT Late leaf spot (Cercosporidium personatum) and peanut rust (Puccinia arachidis) are the most important diseases of peanut (Arachis hypogaea L.) in Haiti. Traditional Haitian peanut varieties are not only susceptible to these diseases but are also typically grown without benefit of a fungicide program. Five trials were conducted from 2015 to 2017 to evaluate the performance of six Valencia varieties in Quartier-Morin, Haiti (with an additional trial in 2017 at the Central Plateau) with respect to yield, resistance to rust and leaf spot diseases, and response to a fungicide program. A split-plot design with four or six replications was used in these studies. In each, “variety” was the whole plot and presence or absence of a fungicide program was the subplot. Valencia market types 309 Red, 309 Tan, M2, M3, SGV0801 and a local landrace were compared with and without Muscle ADV (tebuconazole + chlorothalonil, Sipcam) (2.3 L/ha) applied at 45, 60 and 75 days after planting (DAP). Final disease ratings (late leaf spot and peanut rust) were assessed approximately 94 DAP and plots were harvested the day following. In all trials, 309 Tan variety had the least amount of leaf spot and rust, but resulted in the lowest yield in four out of five trials, averaging 1727 kg/ha across fungicide treatments. M3, M2 and 309 Red were generally the numerically highest-yielding varieties, averaging 2906, 2864 and 2541 kg/ha across fungicide treatments, respectively, but were not statistically higher than the local Haitian Valencia, averaging 2374 kg/ha. Three fungicide applications during the season significantly increased yields in most trials for all varieties except 309 Tan. The highest and lowest average increase in yield from fungicide was for 309 Red (1126 kg/ha) and 309 Tan (103 kg/ha), respectively. The results from this study conducted over 2 years and 4 seasons document that while resistance to late leaf spot and rust is available in Valencia varieties, yield potential is not directly associated with that resistance. Also, use of fungicide improves yield potential in more susceptible varieties.

New Mycodiplosis gall midge (Diptera: Cecidomyiidae) feeding on fungal rusts (Fungi: Pucciniomycetes) that are pathogenic on cultured plants.

Larvae of a gall midge were found feeding on the fungal rust Maravalia pterocarpi (Pucciniomycetes: Pucciniales: Chaconiaceae) infesting the economically important sua tree Dalbergia tonkinensis (Fabaceae) on Hainan Island, China. The adults, pupae and larvae were collected, their morphology was studied and a segment of the Cytochrome Oxidase unit I (COI) mitochondrial gene was sequenced. The gall midge proved to be a species new to science that belongs to the genus Mycodiplosis (Diptera: Cecdiomyiidae). Comparison of the sequence to published Cecdiomyiidae sequences revealed that, despite being undescribed and unnamed, it was previously found in east and south-east Asia to feed on several rust species: Puccinia coronata (Pucciniomycetes: Pucciniales: Pucciniaceae) that develops on Lolium multiflorum (Poaceae), Puccinia sp. on Zea mays (Poaceae), Puccinia arachidis on Arachis hypogaea (Fabaceae) and Puccinia allii on Allium fistulosum (Amaryllidaceae). The new species is described and named here Mycodiplosis puccinivora Jiao, Bu Kolesik. It occurs in China, Japan, Thailand, Bangladesh and possibly Malaysia and Australia. In Hainan it has four to five generations per year.

Field evaluation and components of peanut rust resistance of newly developed breeding lines

ABSTRACT Field, greenhouse, and growth chamber experiments were conducted to determine the level of resistance to Puccinia arachidis Speg. in newly developed breeding lines of peanut (Arachis hypogaea L.). These lines were developed in the UF150 project of the Peanut Collaborative Research and Support Program (Peanut CRSP) as part of the United States Agency for International Development (USAID). Field experiments were carried out in Citra, FL and Tifton, GA from 2010 to 2013. Five genotypes Tifrust-10 and Tifrust-13, and CRSP breeding lines PTBOL3-3, 97x36-HO2-1-B2G-3-1-2-2, and BOL3-7 had the lowest standardized area under the disease progress curve and final disease severity score for rust. The CRSP breeding lines 97x36-HO2-1-B2G-3-1-2-2 and BOL3-7 also appeared to be highly resistant to late leaf spot, caused by Cercosporidium personatum (Berk &amp; M. A. Curtis Deighton). In growth chamber studies, genotypes with longer latent periods generally had lower infection frequencies at 7, 11, and 16 d after inoculation, and smaller percent diseased areas. Latent period and percent diseased area were significantly correlated with stAUDPC. CRSP breeding lines 97x36-HO2-1-B2G-3-1-2-2 and BOL3-7, and plant introductions PI562530, PI568164, and PI298115, were among the genotypes with the lower scores for these components. Several genotypes with multiple disease resistance in different environments and under high disease pressure were identified in these studies. These results indicate sources of rust resistance in the CRSP breeding lines, including several genotypes that could be used as parents in peanut germplasm enhancement programs, and indicate that latent period, percent diseased area, and lesion diameter may be used as indicators for rust resistance in growth chamber studies.

Antifungal Activity of Crude Extracts of Ageratum conyzoides, Cyperus rotundus, and Amaranthus spinosus Against Rust Disease

Puccinia arachidis is an obligate pathogen which infects peanut leaves and causes rust disease. Alternative controls of this disease, particularly to limit the frequent use of synthetic fungicide, have been conducted. One of which is by applying botanical fungicides. Crude extracts of Ageratum conyzoides, Amaranthus spinosus, and Cyperus rotundus were used to suppress the rust disease intensity on Bima peanut cultivar. A. conyzoides extracts at 2.5% and 5.0% concentrations were the most effective biofungicide to reduce the disease. The disease intensity (29.8 % and 30.2 %) recorded at 10 weeks after planting (WAP) was significantly lower than the untreated crops (41.4 %). Both weed extract applications reduced about 50 % of pustule number compared to untreated crops at 10 WAP. Applications of 2.5 % and 5.0 % of ageratum extracts saved yield loss of 67.5 % and 63.5 %. Caryophyllene was observed in the roots, stems, leaves, and flowers of ageratum extracts in considerable amounts based on GC-MS analysis and may attribute to its significant antifungal activity. Higher total phenolic and flavonoid contents were observed in ageratum extracts than in amaranthus and cyperus extracts. Ageratum extracts at concentrations of 2.5 % to 5 % could be used to control peanut rust disease.

Efikasi Agensia Hayati Trichoderma sp. Terhadap Karat Daun (Puccinia arachidis) Pada Kacang Tanah

Kacang tanah (Arachis hypogeae) merupakan bahan pangan yang diminati oleh masyarakat. Kontribusi produksi kacang tanah dari Provinsi Jawa Timur terhadap produksi Nasional mengalami penurunan pada tahun 2016. Faktor penyebab rendahnya hasil panen kacang tanah di Indonesia yaitu penyakit karat daun (Puccinia arachidis). Dalam penelitian ini, pengendalian karat daun pada tanaman kacang tanah dengan jamur antagonis Trichoderma sp. Penelitian ini memiliki tujuan untuk mengetahui bagaimana pengaruh agensia hayati Trichoderma sp. terhadap intensitas serangan penyakit karat daun, jumlah polong dan berat basah polong kacang tanah. Penelitian ini dilaksanakan pada bulan Juli 2017 hingga Maret 2018 di Laboratorium Perlindungan Tanaman Politeknik Negeri Jember dan lahan di Desa Antirogo, Kecamatan Sumbersari, Kabupaten Jember. Penelitian ini menggunakan Rancangan Acak Kelompok non faktorial terdiri dari 4 perlakuan di antaranya A0 (Tebukonazol 0,3 ml/l), A1 (Trichoderma sp. 105cfu/ml), A2 (Trichoderma sp. 106cfu/ml), A3 (Trichoderma sp. 107 cfu/ml) dengan 6 ulangan. Uji data menggunakan ANOVA (Analyze of Varians) dan uji lanjut dengan BNT 5%. Hasil dari penelitian adalah bahwa dari 4 perlakuan tersebut tidak berpengaruh nyata terhadap tingkat intensitas serangan karat daun, jumlah polong serta berat polong kacang tanah. Intensitas serangan Puccinia arachidis berkorelasi negatif terhadap jumlah polong dan berat basah polong.

Mapping of a dominant rust resistance gene revealed two R genes around the major Rust_QTL in cultivated peanut (Arachis hypogaea L.)

A consensus rust QTL was identified within a 1.25 cM map interval of A03 chromosome in cultivated peanut. This map interval contains a TIR-NB-LRR R gene and four pathogenesis-related genes. Disease resistance in plants is manifested due to the specific interaction between the R gene product and its cognate avirulence gene product (AVR) in the pathogen. Puccinia arachidis Speg. causes rust disease and inflicts economic damages to peanut. Till now, no experimental evidence is known for the action of R gene in peanut for rust resistance. A fine mapping approach towards the development of closely linked markers for rust resistance gene was undertaken in this study. Phenotyping of an RIL population at five environments for field rust score and subsequent QTL analysis has identified a 1.25cM map interval that harbored a consensus major Rust_QTL in A03 chromosome. This Rust_QTL is flanked by two SSR markers: FRS72 and SSR_GO340445. Both the markers clearly identified strong association of the mapped region with rust reaction in both resistant and susceptible genotypes from a collection of 95 cultivated peanut germplasm. This 1.25cM map interval contained 331.7kb in the physical map of A. duranensis and had a TIR-NB-LRR category R gene (Aradu.Z87JB) and four glucan endo-1,3 β glucosidase genes (Aradu.RKA6M, Aradu.T44NR, Aradu.IWV86 and Aradu.VG51Q). Another resistance gene analog was also found in the vicinity of mapped Rust_QTL. The sequence between SSR markers, FRS72 and FRS49, contains an LRR-PK (Aradu.JG217) which is equivalent to RHG4 in soybean. Probably, the protein kinase domain in AhRHG4 acts as an integrated decoy for the cognate AVR from Puccinia arachidis and helps the TIR-NB-LRR R-protein to initiate a controlled program cell death in resistant peanut plants.