ABSTRACT
Aims@#This study was designed to examine the enzyme activity of selected virulent isolates of Ganoderma boninense against oil palm. In a separate in vitro assessment, the effect of macronutrients on the mycelial growth of four selected Ganoderma spp. was also tested.@*Methodology and results@#The study involved a comparison of ligninolytic enzymes; lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (Lac) profiling of eight isolates of G. boninense, categorized into three levels of aggressiveness, with two control isolates (G. boninense PER71 and G. tornatum NPG1) using solid-state fermentation (SSF). The Principal Component Analysis (PCA) revealed that the isolates had a significant production of ligninolytic enzymes on day 80. The most aggressive isolate, ET61 had the highest Lac production. As for the macronutrient test, mycelial growth for all the Ganoderma spp. was highly affected by potassium (K).@*Conclusion, significance and impact of study@#The findings of this study elucidated the characteristics of G. boninense in relation to enzyme production for the degradation of oil palm lignin and the identification of essential nutrients involved in the survival and growth of Ganoderma spp. The study provides vital information on the pathogenic characteristics of G. boninense isolates involved in biomass degradation along with the role of nutrient on the growth of Ganoderma spp. that may influence basal stem rot (BSR) management in the field.
Subject(s)
Enzymes , Ganoderma , Palm OilABSTRACT
Aims@#The basal stem rot disease in oil palm is caused by the pathogenic Ganoderma boninense, which is infectious after mating and forming dikaryotic hyphae. This study was aimed to generate a mating-type biomarker for the detection of pathogenic Ganoderma species.@*Methodology and results@#Mating-type region of Ganoderma was amplified using polymerase chain reaction (PCR) and primers flanking the mating-type region of other basidiomycetes. Amplified fragments were sequenced and were identified as the Ganoderma pheromone receptor gene of matB locus called the gprb2 gene. Using this biomarker, the pheromone receptor gene was detected in a total of 107 pathogenic Ganoderma spp. while the gene was not detected in the non-pathogenic Ganoderma lucidum. Phylogenetic tree analyses of the gene fragment encoding the partial amino acid sequence of gprb2 showed clades of close evolutionary relationship among the 107 pathogenic Ganoderma spp. Phylogenetic analyses using deduced amino acid sequences of the Ganoderma pheromone receptor b2 gene, gprb2 with homologous pheromone receptors of other basidiomycetous fungi revealed high conservation of this pheromone receptor within their respective taxonomy.@*Conclusion, significance and impact of study@#A potential mating-type biomarker was successfully identified that could detect pathogenic Ganoderma spp. The research findings will be helpful in oil palm screening to detect pathogenic Ganoderma spp. and gain further insight into the role of the mating-type loci of Ganoderma towards its pathogenesis in causing the basal stem rot disease of oil palm.
Subject(s)
Genes, Mating Type, Fungal , GanodermaABSTRACT
Aims@#The development of an effective biocontrol formulation for inhibition of Ganoderma boninense, a well-known destructive pathogen in oil palm plantation is important to prolong the palm’s lifespan and reduce the losses due to this disease. In this paper, we present some new bioformulations with combination of different types of biocontrol agents in managing basal stem rot (BSR) disease. @*Methodology@#The effectiveness of the treatments designed as T1 (Trichoderma harzianum + Lecanicillium spp. + Streptomyces sundarbansensis + Pseudomonas aeruginosa), T2 (Penicillium simplicissimum + Lecanicillium sp. + S. sundarbansensis + P. aeruginosa), T3 (P. simplicissimum + P. aeruginosa) and T4 (LEStani®) was evaluated through treatment on the oil palm seedlings artificial infected by G. boninense and the results were expressed in disease severity index (DSI), bole severity index (BSI) and ergosterol content.@*Conclusion, significance and impact of study@#All tested treatments (T1-T4) managed to control the severity of the Ganoderma infection from continuously increasing when the treatments were applied either one month before or after artificial inoculation. The disease severity of infected seedlings without treatments had increased for almost 2-fold at the end of the trial. Moreover, T1 had the greatest inhibition of G. boninense with the lowest ergosterol content (a bioindicator of Ganoderma colonization) detected (676.67 g/mL), which is about 1.9-fold lower than control (1273.33 ug/mL) without treatments and a BSI score of 1. Based on the effectiveness among the four tested biocontrol formulations, T1 is the most promising formulation to be further evaluated in the field for control of BSR disease. However, more research is needed in the future to estimate the effective amount for application in open environment.
Subject(s)
Palm Oil , Biological Control Agents , GanodermaABSTRACT
A model to estimate the damage caused by white mold to soybean yield from experimental field data gathered during the summer season of 2009-10 was generated. Six soybean cultivars were grown on six sites of the Savana (Cerrados) region, resulting in a total of nine separate experiments. The gradient of disease intensity (plant stem incidence) and yield was generated through the application of different fungicides and rates three times over the course of the season. The disease incidence in plant stems was evaluated at the R1, R5.2 and R5.5 growing stages. Manual harvest at the physiological ripening stage was followed by grain drying, threshing, and cleaning. Finally, grain yield was estimated in kg/ha, and regression analysis was performed. Nine linear equations representing the damage function were generated. The mean damage function was y = - 6.7 x + 1,000, where y represents grain yield normalized to 1,000 kg/haand x represents WM incidence in plants. To appraise the damage caused by various disease intensities, these models should first be validated. Damage coefficients may be used to determine the level of economic damage.
Desenvolveu-se um modelo para estimar os danos causados pelo mofo-branco (MB) (Sclerotinia sclerotiorum) na cultura da soja, com dados gerados em experimentos de campo conduzidos na safra de soja de 2009/10. Seis cultivares de soja foram cultivados em seis locais perfazendo um total de nove experimentos em distintas regiões edafoclimáticas na região do Cerrado. O gradiente da intensidade da doença, avaliada em função de incidência de sintomas/sinais em hastes, foi gerado pela aplicação de diferentes fungicidas em momentos e doses distintas. A intensidade da doença foi avaliada, nos estádios fenológicos de R1, R5.2 e R5.5. A colheita foi realizada na maturação fisiológica e o rendimento de grãos expresso em kg/ha. As análises de regressão entre o rendimento de grãos e a incidência da doença foram realizadas para todas as combinações obtidas e geraram nove equações lineares da função de dano. Função de dano média de nove experimentos foi R = 1.000 - 6,7 I (onde R = rendimento de grãos normalizado para 1.000 kg/ha e I incidênciaa do MB em plantas). Para estimar o dano causado por intensidades diferentes da doença, esses modelos devem ser previamente validado. Os coeficientes de dano podem ser usados para determinar o limiar de dano econômico
Subject(s)
Ascomycota , Glycine maxABSTRACT
Aims@#The objective of this study is to investigate the potential of fungi isolated from forest soil as biocontrol against Ganoderma boninense, the causal pathogen of basal stem rot disease in Elaeis guineensis Jacq. (oil palm). @*Methodology and results@#Total 195 isolates were isolated from 20 soil samples collected from Crocker Range of Sabah and 54 fungal isolates were identified with 14 of them showed Percentage Inhibition of Radial Growth (PIRG) greater than 50%. A potential fungi (F15) with PIRG of 84.85% was later identified as Penicillium simplicissimum using molecular technique. Microscopy examination on P. simplicissimum and G. boninense interaction showed the evidence on the damage of pathogen hyphae when challenged by P. simplicissimum. The secondary metabolites of P. simplicissimum which may possibly contribute to this observation were later extracted using hexane, ethyl acetate and acetone and the extracts were tested in agar dilution bioassay (0.2 mg/mL to 1.0 mg/mL) against the pathogen. Ethyl acetate extract gave the highest inhibition to G. boninense (14.12 % in 0.4 mg/mL of ethyl acetate extract). @*Conclusion, significance and impact of study@#This is the first report, on the bioactivity of P. simplicissimum isolated from Crocker Range of Sabah against Ganoderma boninense, the causal pathogen of basal stem rot disease. Overall, our results indicated that P. simplicissimum has the potential to be further investigated as a biocontrol agent against G. boninense.
ABSTRACT
Objective To analyze the bacterial diversity in stem rot and healthy plants of Paris polyphylla var. chinensis. Methods Bacterial strains were isolated from rhizomes, stems and leaves of the diseased and healthy plants of P. polyphylla var. chinensis using beef extract-peptone medium. Using 16 S rRNA universal primers 27F/1492R for PCR amplification, combined with DNA sequencing technology to preliminary identification the bacterial strains. Results The bacteria could be divided into 23 microbial species, belonging to 11 genera, isolated from healthy and diseased plants of P. polyphylla var. chinensis. Eleven endophytic bacteria, belonging to 4 genera were contained from healthy plants, in which there were 9, 10, and 5 species isolated from rhizomes, stems and leaves, respectively. Fourteen endophytic bacteria, belonging to 10 genera were contained from diseased plant, in which there were 11, 8, and 3 species isolated from rhizomes, stems, and leaves, respectively. The content of endophytic bacteria in rhizome of healthy plant was the highest, reached up to 2.999 × 105 cfu/g, while that in leaf was the lowest with 7.32 × 104 cfu/g. The quantities of Bacillus species in rhizome (73.3%), stem (67.1%), and leaf (81.8%) of healthy plant were the highest groups, Pseudomonas species in rhizome (35.6%), stem (50.3%) and leaf (60.5%) of diseased plants were the highest groups. Shannon-Wiener index and evenness index of healthy plant of P. polyphylla var. chinensis were higher than that of diseased plants. Conclusion The dominant group in the healthy plant of P. polyphylla var. chinensis was Bacillus, while the dominant groups in the diseased plant of P. polyphylla var. chinensis was Pseudomonas. The population diversity of the cultivable bacteria in healthy plant of P. polyphylla var. chinensis was more abundant than that of diseased plant.
ABSTRACT
In 2010, symptoms of leaf and stem rot were observed on potted plants (Peperomia quadrangularis) in a greenhouse in Yongin, Korea. The causative pathogen was identified as Myrothecium roridum based on morphological data, internal transcribed spacer sequence analysis, and pathogenicity test. To our knowledge, this is the first report of M. roridum causing leaf and stem rot disease on P. quadrangularis in Korea and elsewhere worldwide.
Subject(s)
Korea , Peperomia , Sequence Analysis , VirulenceABSTRACT
In March 2014, a kohlrabi stem rot sample was collected from the cold storage room of Daegwallyong Horticultural Cooperative, Korea. White and fuzzy mycelial growth was observed on the stem, symptomatic of stem rot disease. The pathogen was isolated from the infected stem and cultured on potato dextrose agar for further fungal morphological observation and to confirm its pathogenicity, according to Koch's postulates. Morphological data, pathogenicity test results, and rDNA sequences of internal transcribed spacer regions (ITS 1 and 4) showed that the postharvest stem rot of kohlrabi was caused by Sclerotinia sclerotiorum. This is the first report of postharvest stem rot of kohlrabi in Korea.
Subject(s)
Agar , Ascomycota , DNA, Ribosomal , Glucose , Korea , Solanum tuberosum , VirulenceABSTRACT
In June 2012, leaf spot and stem rot were observed on Wilford Swallowwort plants grown in Cheonan, Korea. Three fungal isolates obtained from the diseased leaves and stems were identified as Stemphylium lycopersici, based on morphological, cultural, and molecular characteristics and pathogenicity. This is the first report of leaf spot and stem rot on Wilford Swallowwort caused by S. lycopersici.
Subject(s)
KoreaABSTRACT
Stem rot was found for the first time on the Asiatic dayflower plant (Commelina communis L.) in Korea. A detailed description of this Korean specimen is given, along with its rDNA internal transcribed spacer sequence. The fungus was identified as Sclerotium rolfsii Saccardo based on mycological characteristics and molecular data.
Subject(s)
Commelina , DNA, Ribosomal , Fungi , Korea , PlantsABSTRACT
Basal stem rot symptoms were found on blueberry seedlings imported from the United States of America in 2008. The fungus obtained from the diseased seedlings was identified as Calonectria colhounii based on morphological and molecular characteristics. The consignments of the blueberry seedlings infected with C. colhounii were destroyed to prevent introduction of the fungus to Korea.
Subject(s)
Americas , Blueberry Plants , Fungi , Korea , Seedlings , United StatesABSTRACT
Stem rot disease was found in garlic (Allium sativum L.) cultivated from 2008 to 2010 in the vegetable gardens of some farmers in Geumsan-myon, Jinju City, Gyeongnam province in Korea. The initial symptoms of the disease were typical water-soaked spots, which progressed to rotting, wilting, blighting, and eventually death. White mycelial mats had spread over the lesions near the soil line, and sclerotia had formed over the mycelial mats on the stem. The sclerotia were globoid in shape, 1~3 mm in size, and tan to brown in color. The optimum temperature for growth and sclerotia formation on potato dextrose agar (PDA) medium was 30degrees C. The diameter of the hyphae ranged from approximately 4 to 8 microm. Typical clamp connection structures were observed in the hyphae of the fungus, which was grown on PDA medium for 4 days. On the basis of the mycological characteristics and pathogenicity of the fungus on the host plants, the causal agent was identified as Sclerotium rolfsii Saccardo. This is the first report of stem rot disease in garlic caused by S. rolfsii in Korea.
Subject(s)
Humans , Agar , Allyl Compounds , Fungi , Garlic , Glucose , Hyphae , Korea , Soil , Solanum tuberosum , Sulfides , Triacetoneamine-N-Oxyl , VegetablesABSTRACT
A fungal isolate collected from infected paprika (Capsicum annuum var. grossum) was characterized as Sclerotinia sclerotiorum based on its ability of sclerotium formation, physiological and molecular properties. When the isolate was grown on potato dextrose agar, oatmeal agar, and malt extract agar, it grew most well on PDA. Optimal temperature and pH for its growth were 25degrees C and pH 7, respectively. The fungal isolate produced sclerotia on PDA within 10 days, and the color and shape of the sclerotia were similar to those of S. sclerotiorum . The ITS rDNA regions including ITS1 and ITS2 and 5.8S sequences were amplified using ITS1F and ITS4 primers from the genomic DNAs of the paprika isolate and other known pathogenic S. sclerotiorum isolated from different crops in Korea, and their nucleotide sequences were determined. Sequence comparison analysis showed the ITS rDNA of the paprika isolate shares 100% sequence identity with those of S. sclerotiorum isolated from red pepper, lettuce and a S. sclerotiorum isolate registered in GenBank DNA database. Neighbor joining analysis based on the ITS rDNA sequence revealed the paprika isolate has very close phylogenetic relationships with known Sclerotinia sclerotiorum isolates. This is the first report that S. sclerotiorum has been found associated with paprika rot in paprika growing countries.
Subject(s)
Agar , Ascomycota , Base Sequence , Capsicum , Databases, Nucleic Acid , DNA , DNA, Ribosomal , Glucose , Hydrogen-Ion Concentration , Korea , Lactuca , Solanum tuberosumABSTRACT
In July 2002, a destructive stem rot of tawny daylily(Hemerocallis fulva) was occurred sporadically in exhibition farm of Gyeongsangnam-do Agricultural Research and Extension Services located in Hamyang-gun, Korea. The fungus also caused collar and crown rot, and systemic wilt or blight of whole plant. White mycelium spread over stems and petioles of infected plants and sclerotia were formed on the old lesions and near the soil surface. The optimum temperature for mycelial growth and scierotial formations was 30degrees C on PDA. The mycelial width ranged 4.2~10.4microm and the color was white, usually many narrow mycelial strand grew in the aerial mycelium and formed clamp connection. The shape of sclerotia was spherical and 1.0~3.2 mm in diameter. The fungus was isolated repeatedly from the infected tissues and confirmed its pathogenicity to Hemerocallis fulva and identified as Sclerotium rolfsii. This is the first report on the stem rot of H. fulva caused by S. rolfsii in Korea.
Subject(s)
Crowns , Fungi , Hemerocallis , Korea , Mycelium , Plants , Soil , VirulenceABSTRACT
A destructive stem rot of tomato (Lycopersicon esculentum) occurred sporadically some farmers' fields in Jinju City, Gyeongnam province in Korea. The infected plants also showed stem, crown rot or whole plant blight. White mycelium spread over stems of infected plants and formed sclerotia on the old lesions nearby soil surface. The fungus showed maximum mycelial growth around 30degrees C. The fungus formed white colony on PDA, usually with many narrow mycelial strands in the aerial mycelium and the width were 4.0~9.8 microm. The typical clamp connections were formed on the mycelium. Numerous sclerotia was formed on PDA at 30degrees C. The shape of sclerotia was globoid and 1.0~3.0 mm in size. The fungus was isolated repeatedly from the infected tissues and the pathogenicity was confirmed to tomato and identified as Sclerotium rolfsii. This is the first report on the stem rot of tomato caused by S. rolfsii in Korea.
Subject(s)
Crowns , Fungi , Korea , Solanum lycopersicum , Mycelium , Plants , Soil , VirulenceABSTRACT
In July 2001, a destructive stem rot of tatarian aster (Aster tataricus) was occurred sporadically in exhibition farm of Gyeongsangnam-do Agricultural Research and Extension Services, in Hamyang, Korea. The fungus also caused collar and crown rot and systemic wilt or blight of whole plant. White mycelium spread over stems and petioles of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth was obtained around 30degrees C but did not grow below 5degrees C or above 45degrees C. The mycelial width ranges 4.2~10.4 microm. and the color is white, usually many narrow mycelial stand grow in the aerial mycelium and formed clamp connection. Numerous sclerotia were formed in artificial media like PDA at 30degrees C. The shape of sclerotia were sphere and 1.0~3.2microm in diameter. The fungus was isolated repeatedly from the infected tissues and confirmed its pathogenecity to aster and identified as Sclerotium rolfsii. This is the first report that Sclerotium rolfsii causes stem rot of tatarian aster in Korea.
Subject(s)
Crowns , Fungi , Korea , Mycelium , Plants , SoilABSTRACT
A destructive stem rot of wild aster (Aster koraiensis) occurred sporadically some farmers' fields in Guman-myon, Kosong-gun, Kyongsangnam-do in 2000. One of the most severely infected field in Kosong showed 28.6 percent of infection rate. The fungus also caused stem or crown rot and systemic wilt or blight of the plants. White mycelium spread over stems and petioles of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth around 30degrees C and did not grow under 5degrees C and over 45degrees C and mycelial width were 4.3~10.2 microm. Colony was white, usually many narrow mycelial stand in the aerial mycelium and formed clamp connection. Numerous sclerotia were formed on PDA at 30degrees C. The shape sclerotia were globoid and 0.8~3.0x0.9~3.4 mm in size. The fungus was isolated repeatedly from the infected tissues and confirmed its pathogenecity to wild aster and identified as Sclerotium rolfsii. This is the first report on the stem rot of wild aster caused by S. rolfsii in Korea.
Subject(s)
Crowns , Fungi , Korea , Mycelium , SoilABSTRACT
In order to find an environment-friendly method to suppress astragal stem rot caused by the isolates of Rhizoctonia solani AG 1 and AG 4, we tested an antagonistic fungus Gliocladium virens G1 was evaluated as a biocontrol agent and estimated inorganic compounds and organic materials were tested for their effect of the disease suppression. G. virens G1 effectively inhibited mycelial growth in a dual culture and caused mycelial lysis in the culture filtrate. No adverse effect was observed when examined for seed germination and seedling growth. Promoted seedling growth was observed with the seed treatment. Seeds of astragal plant were germinated higher in the sterile soil than the natural soil. Of 14 inorganics tested, alum, aluminum sulfate and calcium oxide significantly suppressed the mycelial growth and sclerotial germination. Milled pine bark and oak sawdust also suppressed the mycelial growth. Soil amended with 1% of G. virens G1 composted with pine bark (w/v) significantly controlled astragal stem rot in the glasshouse experiments.