Sclerotium Rolfsii Sacc Research Articles

Effect of Different Carbon and Nitrogen Sources on Sclerotium rolfsii sacc. Mycelial Growth and Sclerotial Development

In vitro studies were conducted on Potato Dextrose Agar using different carbon (C) and nitrogen (N) sources to evaluate their effects on the mycelial growth, and the sclerotial development of three Tunisian Sclerotium rolfsii Sacc. isolates. Radial growth was optimum on basal medium supplemented with ammonium chloride (0.48 gram of nitrogen per liter (g of N.L-1)) as N source but was restricted on L-Arginine and completely inhibited on ammonium acetate amended media (0.48 g N.L-1). Sclerotial initiation occurred from the 3rd to the 12th day of incubation for all tested isolates. Potassium nitrate was the most suitable N source for sclerotial formation whereas sclerotial development was completely inhibited on ammonium acetate amended medium. Optimal sclerotial germination was recorded using L-Arginine (78-80%) followed by L-Asparagine (46-94%) and ammonium chloride (46-88%) as N sources. Nevertheless, the lowest sclerotial germination rate was noted on sodium nitrate and ammonium acetate amended media. As for C sources (16 gram of carbon per liter (g of C.L-1)), optimal radial growth occurred using D-mannitol for Sr1 and Sr2 isolates and maltose for Sr3, but no mycelial growth was recorded using sodium citrate for all isolates. All C sources tested, except sodium citrate, were suitable for sclerotial formation, production, and germination. Mature sclerotia became brownish after 6 to 12 days of incubation and sclerotial production was highest using D-mannitol, maltose, and D-glucose, depending on isolates used, as C sources. Optimal germination of sclerotia was noted using D-glucose, D-mannitol and maltose for Sr1 isolate, maltose for Sr2 and D-glucose and maltose for Sr3. It was concluded that N and C sources are both important factors for the growth of S. rolfsii and its survival.

Standardization of inoculation technique to identify the sources of resistance against stem and pod rot of groundnut

A technique was standardized to screen for resistance to stem rot ( Sclerotium rolfsii Sacc.) in groundnut ( Arachis hypogaea L.). A total of seven different inoculation techniques were screened by using susceptible genotype TMV-2. The techniques involved inoculation of 10 day old groundnut plants raised in pots by spreading mycelial propagules of S. rolfsii grown on sorghum grain medium (SGM) on soil surface, Inoculum spread on the soil surface and covered with groundnut leaf debris, Inoculum placed around the collar region, Inoculum placed around the collar region and covered with groundnut leaf debris, Inoculum mixed in the soil, Inoculum mixed in the soil and covered with groundnut leaf debris, Agar disc method. Among these techniques inoculum spread on the soil surface and covered with groundnut leaf debris was found to be most efficient in getting highest per cent incidence of stem rot (84.86%) and pod rot (70.48%).

Efficacy of different fungicides and Trichoderma spp. against stem rot of groundnut incited by Sclerotium rolfsii Sacc.

Stem rot caused by Sclerotium rolfsii Sacc. Isone of the major diseases of groundnut causing serious crop losses.Six fungicides and sixteen Trichoderma isolates were screened in vitro against Sclerotium rolfsii. Among fungicides, carboxin 37.5 % + thiram 37.5 %, tebuconazole 2% DS and mancozeb75% WP were effective in inhibiting the growth of the pathogen. Trichoderma isolates viz., T16, Th and Th11 were able to significantly inhibit mycelial growth of S. rolfsii.

Evaluation of plant extracts, fungicides, bio-agent and soil amendments against foot and root rot disease of betelvine caused by Sclerotium rolfsii under field condition

The studies were carried out on the management of foot and root rot disease caused by Sclerotium rolfsii Sacc. of betelvine (Piper betle L.) during April, 2017 to April, 2018 in a betelvine orchard (baroj) in the experimental farm of Sher-e-Bangla Agricultural University, Dhaka. There were 10 treatments, namely Provax 200, Tilt 250 EC, Score 250 EC, Pencozeb 80 WP, Garlic clove extract, Allamanda leaf extract, Poultry waste, Vermi-compost, Trichoderma harzianum and Control. The in-vivo evatuation, plant was inoculated by S. rolfsii after six month of plantation. The evaluation revealed that the lowest disease incidence of 8.33% was found in Provax 200 whereas the highest disease incidence of 91.67 was recorded under the untreated control treatment. The maximum of 90.91% reduction in disease incidence over control was found under Provax 200, which was significantly higher compared to all other treatments. Among the treatments, Provax 200 was noted as the most effective fungicide followed by Score 250 EC. The highest yield (7.57 t/ha) at 120 days after inoculation was found in case of Provax 200 which was 330.1% increased over untreated control. Stem and soil treated with Provax 200 including spraying at 3 days after inoculation, then sprayed at 7 days’ intervals minimized disease incidence and increased yield. Among the eco-friendly approach, Garlic clove extract, Trichoderma harzianum and soil amended with Vermi-compost also showed better performance in controlling foot and root rot disease of betelvine as compared to control.
 Bangladesh J. Agril. Res. 44(4): 669-677, December 2019

The Potential of Arbuscular Mycorrhizal Fungi (AMF) as Biocontrol Agent Against Stem Rot Diseases Caused Sclerotium rolfsii of peanut (Arachis hypogaea L)

This study was conducted to assess the biocontrol efficacy of arbuscular mycorrhizae fungi (AM Fungi) against stem rot disease caused by Sclerotium rolfsii Sacc. in peanut. The AM Fungi can be associated with almost all types of plants. The purpose of this study was to obtain isolates of arbuscular mycorrhiza fungi (AMF) as a potential biofungisida against Sclerotium rolfsii and can characterize the mechanism of the FMA in controlling S.rolfsii (salicylic acid) on peanut plants. The AM Fungi inoculant (40 spores g-1 in concentration) was introduced to peanut seedling (25 g plant-1 ) at planting time where as Sclerotium rolfsii inoculated 30 days after planting time. The experiment was arranged in the completely randomized design (CRD), which is 7 treatment sand repeated 10 times in the greenhouse experiment. The data were analyzed using analysis of variance (ANOVA) using STAT program 8 and the Tukey test at 5% significance level. The AM Fungi treatments showed significantly redused the percentage of disease severity in infected peanut plants around 34.28% - 57.15% and longer incubation period, respectively. They increased root colonization (20,00 - 46.67%) with a middle to high category. The AM Fungi C isolate (isolated from Solok county), and the A isolate (isolated from Payakumbuh city) were the best as a biocontrol against S rolfsii (57.15%), followed by isolate D (isolated from Padang Pariaman county) 54,30 %. They also increased Salicylic acid content 1,4 times (70.72 ppm) compared to control (49,59 ppm). It can be concluded that the application of AM Fungi as a biocontrol agent played an important role in plant resistance and exhibit greater potential to protect peanut plants against S. rolfsii.

Screening of fungicides and bio-control agents against Sclerotium rolfsii (Sacc.) causing collar rot in Lentil

Lentil is an important pulse crop, contributes about 8-9% of the total pulse production in India and is also a major source of protein, minerals and vitamins. Collar rot of lentil is an important seedling disease caused by Sclerotium rolfsii Sacc. In this study, twenty isolates (Th1-Th20) of Trichoderma harzianum, one isolate of Pseudomonas fluorescence and nine commercially available fungicides were tested in vitro for their efficacy in inhibiting the growth of the pathogen. Trichoderma harzianum isolate Th16 and Th14 were found to inhibit maximum mycelial growth of the pathogen. The complete inhibition of mycelial growth of Sclerotium rolfsii was found with Propiconazole, Tabuconazole, Hexaconazole, Ridomil and Carbendazim+ Mancozeb at all (0.03%, 0.05% and 0.1%) concentrations. Other fungicides (Captan, Mancozeb and Carbendazim) also showed significant inhibition of the mycelial growth of the pathogen. No inhibition was recorded in the treatment with copper oxychloride even at 0.2% concentration.

Cost benefit ratio of bio-control agents, botanicals and fungicide in the management of white rot of onion caused by Sclerotium rolfsii Sacc. in Manipur

The research investigation was undertaken to evaluate the economics of the management of white rot of onion by Trichoderma harzianum, Trichoderma viride, garlic (Allium sativum L.), turmeric (Cucurma longa L.), sweet flag (Acorus calamus L.) and Carbendazim (50% WP). Carbendazim recorded highest gross return followed by T. harzianum and T. viride respectively. Carbendazim also recorded highest net return followed by T. harzianum and garlic respectively. Among the treatments, Carbendazim gave the highest net return cost benefit ratio of 1:3.25. Garlic extract gave cost benefit ratio of 1:2.96. T. harzianum gave cost benefit ratio of 1:2.89.

Effectiveness of Extract of Jeringau Rhizome (Acoruscalamus L.) on Mushrooms Sclerotium rolfsii Sacc. Causing Stem Rot on Peanut Plant (Arachis hypogaea L.)

Sclerotium rolfsii Sacc. is one of the important pathogens in peanuts. The controls that have been undertaken by farmers generally use synthetic pesticides. However, the use of synthetic pesticides has various negative impacts on the environment and human health. Therefore a technology is needed to produce environmentally friendly pesticides and effectively control stem rot. This study aims to determine the effectiveness of the Jeringau rhizome extract against S. Rolfsii fungi. The results showed that the crude extract of the Jeringau rhizome was able to inhibit the growth of S. rolfsii fungi in vitro on PDA media. Minimum Inhibitory Concentration (MIC) crude extract of jeringau rhizome was 0.50%. The inhibitory power of the extract with a concentration of 0.10% to 0.50% increased from 48.17% to 100%. The treatment of extract concentration of 0.50% showed fungicidal properties against S. rolfsii.

CIP elicitors on the defense response of A. macrocephala and its related gene expression analysis

Plant-derived elicitor is a new type of plant vaccine developed in the contemporary era, and it has safe and broad application prospects in organic agriculture. Research on defense mechanisms triggered by elicitor has become a hot topic in recent years. The Chrysanthemum indicum polysaccharide (CIP) obtained by separation and purification from Chrysanthemum indicum was used as an elicitor in this work. This elicitor has been shown to be effective in Atractylodes macrocephala Koidz (A. macrocephala) against Sclerotium rolfsii sacc (S. rolfsii) infection and soil-borne diseases. However, the mechanism of induced disease resistance has not been elucidated. In this research, we study the CIP-induced A. macrocephala defense response from the level of signal molecules and the defensive enzyme gene expression. Several defense responses to CIP treatment have been found in A. macrocephala, including early hydrogen peroxide (H2O2) production, accumulation of salicylic acid (SA) and increased phytoalexin (PA) content. In addition, CIP significantly increased the activity of related defense enzymes in A. macrocephala. RT-qPCR analysis showed that defense-related genes such as polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were up-regulated after CIP treatment. To obtain the sequence of the defense enzyme gene, we are the first to provide a public and comprehensive A. macrocephala database by transcriptome sequencing. These results together demonstrate that CIP triggers defense responses in A. macrocephala. Our research not only provides further research on immune mechanism between plant and elicitor, but also sheds new light on strategy for biocontrol in the future.

Use of organic composts to suppress bentgrass diseases in Agrostis stolonifera

Turfgrasses are affected by fungal diseases and their chemical control is currently limited by the legislation and the impact on the environment of fungicides and the possible development of fungicide resistance. This study was carried out during three years to evaluate the antagonistic effect of the microbiota associated with organic composts. Two composts were produced from agro-industrial residues, P1 and P2. Fungi from both composts were isolated and identified and their antagonistic capacity was evaluated, in vivo and in vitro tests, against Sclerotium rolfsii Sacc, Clarireedia gen. nov. (formerly Sclerotinia homoeocarpa (Benn, 1937)) and Rhizoctonia solani (Kühn 1858). In vivo tests were run for Agrostis stolonifera L., seeded in P1, P2 and a commercial peat (T) based substrate (Hansa Torf Floragard, Germany), in 100 mL pots. A part of each substrate was submitted to a thermic treatment, obtained Pt, P1t and P2t substrates. Antagonistic properties of the P, P1 and P2 were compared with substrates with thermic treatment. In the in vitro tests Trichoderma atroviride and Trichoderma asperellum showed higher growth than the tested pathogenic agents. T. atroviride showed the best antagonistic capacity, with inhibition percentages of 67.5%, 63.8% and 62.5% against Clarireedia spp., S. rolfsii and R. solani, respectively. In the in vivo tests, the efficacy and biological control index (BCI) were higher in P1 and P2 than in P. BCI ranged from 1.66 (Pt) to 39.03 (P2) on S. rolfsii control, from 1.38 (Pt) to 14.66 (P1) on Clarireedia spp. control, and from 1.87 (Pt) to 21.45 (P1) for R. solani control. Compost P2 showed the highest suppressive effect on the studied soil diseases in turfgrass, which did not occur when its microbiota was eliminated by thermic treatment.

English

English

Phenotypic and genotypic screening of common bean (Phaseolus vulgaris L.) landraces for resistance to collar rot fungus (Sclerotium rolfsii Sacc.) in North of Iran

Collar rot or southern blight is a serious soil-borne disease in common bean (Phaseolus vulgaris L.) at the North of Iran caused by the fungus Sclerotium rolfsii Sacc. which leads to intense yield reduction in a dwarf bean that is cultivated in Guilan Province. Thirty improved landraces of Guilan dwarf bean were exposed to the infectious disease with the most pathogenic isolate of S. rolfsii, to identify the resistant landraces. Disease Severity Index and some traits were evaluated in greenhouse experiments. Phenotypic screening of the genotypes after scoring and multivariate analysis showed one resistant (Pach-08), 21 tolerant or semi-susceptible and eight completely susceptible genotypes. Also, eight specific SCAR markers linked with resistance to collar rot disease were studied. It was shown that although all SCAR markers were able to identify the resistant genotype (Pach-08), only SMe1Em5 marker could separate susceptible and tolerant genotypes. There were significant relation between the trait “total damage per pot, 21 day” and three SCAR markers (Phs, SAU5, SF6EM3). Overall, indirect selection for resistance to collar rot disease in the Guilan dwarf bean can be achieved through the three SCAR markers.

Mycelial compatibility groups, pathogenic diversity and biological control of Sclerotium rolfsii on turfgrass

Sclerotium rolfsii Sacc. (the sclerotial state of Athelia rolfsii (Cruzi) Tu and Kimbrough), the soil-borne pathogen on several plants all over the world, has been previously reported from Turkey on certain plants. In this study, turfgrass areas in 9 provinces of Turkey were firstly surveyed for S. rolfsii, and samples showing chlorotic, reddish-brown, and frog-eye shaped circular patches were collected. Totally, 32 Sclerotium rolfsii isolates were obtained from these areas. One mycelial compatibility group (MCG) was identified among S. rolfsii isolates. Disease severity in pathogenicity tests carried out in the greenhouse ranged from 83.74 to 92.87%. Identification of fungal and bacterial isolates used in the study was performed by DNA sequencing analysis. Five antagonistic bacterial strains, previously found as effective on controlling some fungal pathogens, were tested to determine their antifungal effects against the southern blight by using seed coating method in greenhouse conditions. In consequence of the biological control studies, Bacillus cereus 44bac and Stenotrophomonas rhizophila 88bfp were found more effective than the other strains with the ratio of 91.00 and 90.11%, respectively.

Effect of variability and edaphological characteristics on growth of Sclerotium rolfsii (Sacc) causing collar rot disease of sunflower in coastal region of West Bengal, India

Sunflower is an important oilseed crop in India. One of the major diseases is collar rot caused by Sclerotium rolfsii (Sacc). This study was conducted during 2014–15 and 2015–16 under in-vitro condition. To see the effect of soil temperature and soil moisture, the S. rolfsii (Sacc). was grow at different temperature and at different moisture level. Results showed that among the different soil pH tested, pH5.7 was the best for colonization on wheat seeds 61.67% followed by 6.1(58.33%). In case of soil temperature most preferable temperature for mycelial grow of the pathogen was 30°C. The pathogen grown best in 30% soil moisture content followed by 25%. Variations were observed in colony morphology, mycelial growth, sclerotial size, colour and number of sclerotia. The number of sclerotia in different isolates varied from 352 (WBSR4) to 411 (WBSR9). Twenty five combinations showed compatible reaction out of 36 pairings in mycelial compatibility studies.

Molecular insights into development of Trichoderma interfusants for multistress tolerance enhancing antagonism against Sclerotium rolfsii Sacc.

The current study aimed at developing diverse Trichoderma fusants for fungicides, drought, and salt tolerance with enhanced antagonistic activity against Sclerotium rolfsii Sacc. Trichoderma virens NBAII Tvs12 (mycoparasitic) and Trichoderma koningii MTCC796 (multistress tolerant) were used as parental strains for development of interspecific protoplast fusants. A total of 36 stable fusants were used for mycoparasitism, fungicides, and abiotic stresses (drought and salt) tolerance. The results revealed 20 homozygous progenies showing characteristics of either one parental strain and 14 heterozygous mutants depicting traits of both parental strains. A novel concept of inhibition coefficient was established using growth-related key parameters that represent the pathogen biology and the biocontrol-related biophysics of Trichoderma fusants. The results indicated a differential inhibition coefficient of the test pathogen and the highest (92.88%) inhibition coefficient of S. rolfsii was observed by interstable fusant Fu21. It also grew better under fungicides and abiotic stress (drought and salt) conditions. The molecular characterization and heterozygosity analysis evidenced the highest observed heterozygosity (0.5441) and gene flow (0.3872) in stable heterozygous Fu21. Principal coordinates analysis exhibited 62.7% of total variability. The ecofriendly heterozygous Trichoderma fusant (Fu21) might be useful for biocontrol ofstem rot disease under adverse conditions or as a part of integrated disease management.

Molecular heterozygosity and genetic exploitations of Trichoderma inter-fusants enhancing tolerance to fungicides and mycoparasitism against Sclerotium rolfsii Sacc.

Protoplast fusion is an imperative tool to develop Trichoderma inter-fusants having desire traits through genetic manipulation. Study designed to develop diverse Trichoderma fusants for fungicide tolerance (Mancozeb, Thiram, Tebuconazole, and Carbendazim) and enhanced mycoparasitic activity against Sclerotium rolfsii sacc. The mycoparasitic T. virens NBAII Tvs12 and fungicide tolerant T. koningii MTCC 796 were utilized for protoplast fusion. The derived inter-fusants were subjected to diploidization using d-camphor in minimal media followed by successive three sub culturing onto potato dextrose agar to obtain 36 stable fusants. The stable fusants were employed for conidial size, fungicide tolerance, mycoparasitism, gene specific SSR amplification and molecular heterozygosity analysis. The results explained that 22 homozygous mutants illustrated characteristic of either one parental strain and 14 heterozygous recombinants depicted traits of both parental strains. The antagonistic activity of fusants against S. rolfsii depicted highest growth inhibition (87.91%) by potent inter-fusant (Fu 21) with improved fungicide tolerance capacity. The molecular study revealed highest observed heterozygocity (0.544), coefficient of gene differentiation (0.526) and gene flow (0.387) by Fu 21 indicating better genetic exploitation of parental strains into that fusant with good genetic purity. Principal coordinate analysis of fusants and parental strains exhibited 65.07% total variation and confirmed the scattering pattern matched with UPGMA clustering pattern. The stable heterozygous Fu 21 derived from inter-fusion between Tvs 12 and MTCC 796 might be useful to practice eco-friendly bioformulation tolerance to fungicides for effective integrated stem rot disease management in groundnut.

Exploring Combined Effect of Abiotic (Soil Moisture) and Biotic (Sclerotium rolfsii Sacc.) Stress on Collar Rot Development in Chickpea.

Plants being sessile are under constant threat of multiple abiotic and biotic stresses within its natural habitat. A combined stress involving an abiotic and a biotic factor reportedly increases susceptibility of the plants to pathogens. The emerging threat, collar rot disease of chickpea (caused by Sclerotium rolfsii Sacc.) is reported to be influenced by soil moisture condition (SMC). Hence, we studied the influence of differential SMC viz. upper optimum (100%), optimum (80%), lower optimum (60%), and limiting (40%) soil moisture conditions on colonization and collar rot development over the course of infection in two chickpea cultivars, Annigeri (susceptible to collar rot) and ICCV 05530 (moderately resistant to collar rot). Disease incidence was found to be directly proportional to increase in soil moisture (R2 = 0.794). Maximum incidence was observed at 80% SMC, followed by 100 and 60% SMC. Expression of genes (qPCR analysis) associated with host cell wall binding (lectin) and degradation viz. endopolygalacturonase-2, endoglucosidase, and cellobiohydrolase during collar rot development in chickpea were relatively less at limiting soil moisture condition (40%) as compared to optimum soil moisture condition (80%). As compared to individual stress, the expression of defense response genes in chickpea seedlings were highly up-regulated in seedlings challenged with combined stress. Our qPCR results indicated that the expression of defense-related genes in chickpea during interaction with S. rolfsii at low SMC was primarily responsible for delayed disease reaction. Involvement of moisture and biotic stress-related genes in combined stress showed a tailored defense mechanism.

Assessing fungicides for seedling protection of cucumber to collar rot disease caused by Sclerotium rolfsii

Sclerotium rolfsii Sacc. is known to be a serious pathogen on many crops of economic importance including cucurbits. Due to proliferic growth and ability to forming sclerotia, this pathogen is the major constraint in successful cultivation of cucumber. The present investigation was thus carried out to evaluate the potential of nine different fungicides i.e. carbendazim, thiophenate methyl, vinclozoline, captan, copper oxychloride, mancozeb, hexaconazole, mycobutanil and propiconazole at different concentrations of 10, 50, 100 and 150 ppm, on the growth inhibition of S. rolfsii . The primary assessment was made on in vitro screening of fungicides and its concentration whereby hexaconazole at lowest concentration (10 ppm) rendered the most vital effect (P≤0.0001) on growth reduction ability followed by propiconazole and mycobutanil. No growth of S. rolfsii observed on plates amended with hexaconazole when the concentration was further increased. Similar effect was traced in an experiment conducted on root trainer. The percent infected plant also provided the same impact of fungicides received in toxic-assay experiment. Maximum seedlings protection of cucumber was achieved through seed application of hexaconazole even at lowest concentration (P≤0.01); similarly, no mortality was detected on higher concentration of this fungicide. Although our result directly claiming the best effect of hexaconazole but we propose to use a combination of fungicides from different groups in order to avoid resistance development in S. rolfsii against a particular fungicide. A combination of carbendazim and hexaconazole is hereby proposed for seedling protection of cucumber to S. rolfsii .

Streptomyces sp. RP1A-12 mediated control of peanut stem rot caused by Sclerotium rolfsii

Sclerotium rolfsii Sacc. is a destructive soilborne fungal pathogen with a wide host range that includes peanuts. Biological control offers an interesting alternative to fungicides for sustainable management of soilborne diseases. The current investigation is aimed at evaluating one potential biocontrol agent Streptomyces sp. RP1A-12 for growth promotion and the management of peanut stem rot disease caused by S. rolfsii under field conditions. Preliminary studies conducted under in vitro and the greenhouse conditions showed promising results against the stem rot pathogen. Further in vitro and pot experiments conducted to assess Streptomyces sp. RP1A-12 for its growth promoting abilities using whole organisms have shown an increase in seed germination, root and shoot length. Other parameters like nodule number and plant biomass were also significantly increased over control treatments indicating that the test bioagent possesses growth promoting abilities along with disease suppression capabilities. Subsequently field studies were carried out for two consecutive rainy seasons. The bioagent was applied as whole organism and partially purified crude metabolites. Results indicate the bioagent reduced stem rot disease incidence by 64–67% and 22–49% respectively in two field trials conducted with notable increase in yield. Partially purified Streptomyces sp. RP1A-12 metabolites exhibited an even greater effect in reducing the incidence and severity of stem rot compared to the pathogen inoculated control.

English

English