Morphological and Molecular Analysis of Fungal Species Associated with Blast and Brown Spot Diseases of Oryzae sativa

Fungal diseases; blast, and brown spot in rice incur severe yield losses worldwide. Blast is caused by Magnaporthe oryzae, while Bipolaris oryzae is reported as the main causal organism of brown spot. Both diseases cause leaf lesions which are difficult to be differentiated by symptomatology until the late stages. Early detection and differentiation of the lesions would help the adoption of disease management strategies specific to the pathogen and will prevent the native impact on the quality and quantity of rice yields. This study was conducted in the Northern Province of Sri Lanka over five consecutive rice cultivating seasons to characterize the causal fungi of rice blast and brown spot diseases by morphological and molecular means and to develop a visual guide to differentiate the two diseases. Disease incidence was recorded in 114 fields from 2017 to 2019, and fungal isolates associated with lesions of both the diseases were cultured and subjected to morphological and molecular characterization. Competitive growth interaction between M. oryzae and the more common individual fungal isolates of the brown spot lesions, was evaluated. Fungal metagenomics analysis was conducted for the fungal spp. isolated from brown spot lesions. A suppression of blast accompanied by an increased incidence of brown spot disease was observed during the study period. M. oryzae was confirmed to be the causal organism of the blast while over 20 species of fungi were identified to be associated with brown spot lesions through morphological, molecular studies, and metagenomics analyses. Fungal ITS region sequencing revealed considerable genetic variation in the highly conserved region of DNA sequences of blast and brown spot fungal isolates. B. oryzae, Curvularia, and Microdochium species were commonly isolated from brown spot lesions. In vitro competitive growth interaction among the fungal isolates revealed growth suppression of M. oryzae by the fungal isolates associated with the brown spot lesions. Similarly, it can be speculated that the abundance and severity of blast in the field may have an influence on brown spot associated fungi. A simple visual guide was developed to differentiate blast and brown spot lesions. The findings would be highly useful in the timely management of these major fungal diseases affecting rice.

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Application of Wood Vinegar for Fungal Disease Controls in Paddy Rice

Applied Environmental Research ◽

10.35762/aer.2016.38.3.7 ◽

2016 ◽

pp. 77-85 ◽

Cited By ~ 2

Author(s):

Wilawan Chuaboon ◽

Nattapone Ponghirantanachoke ◽

Dusit Athinuwat

Keyword(s):

Disease Incidence ◽

Rice Variety ◽

Fungal Diseases ◽

Brown Spot ◽

Curvularia Lunata ◽

Bipolaris Oryzae ◽

Promising Alternative ◽

Shoot Height ◽

Wood Vinegar ◽

Brown Leaf

A survey of an outbreak of fungal diseases of rice variety Phitsanulok2 (PLS91014-16-1-5-1) was conducted in Thailand during June 2014 to January 2015 using aW-random sampling pat-tern. The study revealed the incidence of several diseases including brown spot (Bipolaris oryzae), narrow brown leaf streak (Cercospora oryzae), and dirty panicle (Alternaria padwickii, C. oryzae, Curvularia lunata, Fusarium semitectum, and B. oryzae). This study evaluated the ef-ficacy of wood vinegar for control of these fungal diseases. A compleel randomized design was used, using the above variety in 3 replications. In the laboratory we found wood vinegar to be effective in inhibiting growth of representative pathogens such as C. lunata,B. oryzae,F. semi-tectum, and A. padwickii, the causal agent of dirty panicle disease. The field results confirmed the efficacy of wood vinegar under greenhouse conditions, with significantly reduced disease incidence of brown spot and dirty panicle, and significantly enhanced germination, seedling vigor,shoot height, root length, and fresh weight, when compared with the untreated control. However, seed treatment and 6 foliar sprays of wood vinegar under field conditions at Ang Thong showed no significant differences from the conventional treatment in suppression of brown spot, narrow brown leaf streak, and dirty panicle. The result demonstrates a promising alternative approach to control of key rice diseases.

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Using Commercial Compost as Control Measures against Cucumber Root-Rot Disease

Journal of Mycology ◽

10.1155/2013/324570 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 7

Author(s):

Kamel Kamal Sabet ◽

Magdy Mohamed Saber ◽

Mohamed Adel-Aziz El-Naggar ◽

Nehal Samy El-Mougy ◽

Hatem Mohamed El-Deeb ◽

...

Keyword(s):

Root Rot ◽

Control Measure ◽

Disease Incidence ◽

Pathogenic Fungi ◽

Pythium Ultimum ◽

Control Measures ◽

Infested Soil ◽

Fungal Isolates ◽

Cucumber Root

Five commercial composts were evaluated to suppress the root-rot pathogens (Fusarium solani (Mart.) App. and Wr, Pythium ultimum Trow, Rhizoctonia solani Kuhn, and Sclerotium rolfsii Sacc.) of cucumber plants under in vitro and greenhouse conditions. In vitro tests showed that all tested unautoclaved and unfiltrated composts water extracts (CWEs) had inhibitor effect against pathogenic fungi, compared to autoclaved and filtrated ones. Also, the inhibitor effects of 40 bacteria and 15 fungi isolated from composts were tested against the mycelial growth of cucumber root-rot pathogens. Twenty two bacteria and twelve fungal isolates had antagonistic effect against root-rot pathogens. The antagonistic fungal isolates were identified as 6 isolates belong to the genus Aspergillus spp., 5 isolates belong to the genus Penicillium spp. and one isolate belong to the genus Chaetomium spp. Under greenhouse conditions, the obtained results in pot experiment using artificial infested soil with cucumber root-rot pathogens showed that the compost amended soil reduced the percentage of disease incidence, pathogenic fungi population, and improved the cucumber vegetative parameters as shoot length, root length, fresh weight, and dry weight. These results suggested that composts are consequently considered as control measure against cucumber root-rot pathogens.

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Effective Management of Cucumber Powdery Mildew with Essential Oils

Agriculture ◽

10.3390/agriculture11111177 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1177

Author(s):

Yasser S. Mostafa ◽

Mohamed Hashem ◽

Ali M. Alshehri ◽

Saad Alamri ◽

Ebrahem M. Eid ◽

...

Keyword(s):

Powdery Mildew ◽

Essential Oils ◽

Disease Incidence ◽

Its Region ◽

Dry Weight ◽

Positive Control ◽

Powdery Mildew Fungus ◽

Membrane Injury ◽

Cucumber Powdery Mildew

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.

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Inhibitory Effect of Trichoderma asperellum Isolate against Ralstonia solanacearum Causing Brinjal Wilt

Annals of Bangladesh Agriculture ◽

10.3329/aba.v24i2.55788 ◽

2021 ◽

Vol 24 (2) ◽

pp. 107-120

Author(s):

SMN Islam ◽

SS Siddique ◽

MZH Chowdhury ◽

NJ Mishu

Keyword(s):

Ralstonia Solanacearum ◽

Disease Incidence ◽

Its Region ◽

Inhibitory Effect ◽

Dual Culture ◽

Trichoderma Asperellum ◽

In Planta ◽

Quantitative Test ◽

Trichoderma Isolate

A native Trichoderma isolate was collected from the agricultural soil of Gazipur. This isolate was identified as a Trichoderma asperellum through morphology and analysis of internal transcribed spacer (ITS) region of ribosomal RNA gene sequence and reconstruction of the phylogenetic tree. The antagonistic effects of the newly identified T. asperellum isolate were assessed against brinjal bacterial wilt caused by Ralstonia solanacearum both in vitro and in planta. Both qualitative and quantitative bioassays were conducted in vitro. For qualitative tests, dual culture and antibacterial activity were carried out, and pathogen growth was observed visually. The antagonism of T. asperellum cell free culture filtrate on the growth of R. solanacearum was conducted in a quantitative test. Successful antagonism was recorded after both in vitro qualitative tests. In addition, the lowest colony forming unit was recorded in 100% of CFC (2.4±0.51 ×103 cfu/ml) in quantitative test. The T. asperellum inoculated plant showed low disease incidence (13.33%) when seedlings were challenged with R. solanacearum in planta experiment. Disease incidence was 100% for seedlings when treated with only R. solanacearum. The results showed that the isolated and identified T. asperellum isolate suppressed R. solanacearum growth in vitro and protected the seedling from wilting in planta. Therefore, this isolate could be considered as a potential isolate. Ann. Bangladesh Agric. (2020) 24(2) : 107-120

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Studies on the behaviour of some fungal diseases of rice in the mangrove swamp ecology at Warri, south eastern Nigeria

Acta Agronomica Hungarica ◽

10.1556/aagr.51.2003.4.8 ◽

2003 ◽

Vol 51 (4) ◽

pp. 429-436

Author(s):

E. A. Maji ◽

E. D: Imolehin

Keyword(s):

Disease Incidence ◽

Block Design ◽

Rice Variety ◽

N Fertilization ◽

Brown Spot ◽

Bipolaris Oryzae ◽

Southeastern Nigeria ◽

Mangrove Swamp ◽

Main Plot ◽

Cropping Seasons

Studies on the ecological behaviour of Cochliobolus miyabeanus (Ito et Kurib.) Drechsl. ex Dast., syn. Bipolaris oryzae (Breda de Haan Shoem.), the causal agent of brown spot in rice (Oryza sativa L.), were carried out in the tidal mangrove swamp at Warri Experimental Farm, Southeastern Nigeria. A split randomised complete block design with four replications was used. Monthly transplantings from July to September formed the main plot, which was subdivided into control and N-treated subplots. Disease incidence increased when transplanting was delayed. This was probably due to the fact that flowering coincided with environmental conditions favourable for disease development from November to February. Nitrogen fertilization at 40 kg N/ha significantly (P=0.05) reduced C. miyabeanus incidence in 1997/1998, but not in the 1998/1999 and 1999/2000 cropping seasons at the same site. The grain yields of ROK 5, a medium-duration improved rice variety (approx. 150 days), were significantly (P=0.05) reduced in late-transplanted crops (September to November) in spite of adequate N fertilization. Mangrove mud was not an important source of C. miyabeanus propagules. The incidence of leaf scald caused by Monographella albescens (Thum) Parkinson, Sivanesan and Booth syn. Microdochium oryzae (Hashioka and Yokogi) Samuels and Hallet, and of leaf smut caused by Etyloma oryzae Miyake was generally stimulated by N application.

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Sensitivity of Bipolaris oryzae Isolates Pathogenic on Cultivated Wild Rice to the Quinone Outside Inhibitor Azoxystrobin

Plant Disease ◽

10.1094/pdis-12-18-2267-re ◽

2019 ◽

Vol 103 (8) ◽

pp. 1910-1917 ◽

Cited By ~ 2

Author(s):

Claudia V. Castell-Miller ◽

Deborah A. Samac

Keyword(s):

Cytochrome B ◽

Fungicide Resistance ◽

Wild Rice ◽

Brown Spot ◽

Bipolaris Oryzae ◽

Qoi Fungicides ◽

Quinone Outside Inhibitor ◽

Group I ◽

Mitochondrial Cytochrome B

The occurrence of fungal brown spot, caused by Bipolaris oryzae, has increased in cultivated wild rice (Zizania palustris) paddies in spite of the use of azoxystrobin-based fungicides. The active ingredient blocks electron transfer at the quinone outside inhibitor (QoI) site in the mitochondrial cytochrome b within the bc1 complex, thus obstructing respiration. The in vitro averaged EC50 of baseline isolates collected in 2007 before widespread fungicide use was estimated to be 0.394 µg/ml with PROBIT and 0.427 µg/ml with linear regression analyses. Isolates collected during 2008, 2015, and 2016 had a range of sensitivity as measured by relative spore germination (RG) at a discriminatory dose of 0.4 µg/ml azoxystrobin. Isolates with a higher (≥80%) and lower RG (≤40%) had the wild type nucleotides at amino acid positions F129, G137, and G143 of cytochrome b, sites known to be associated with QoI fungicide resistance. Two Group I introns were found in the QoI target area. The splicing site for the second intron was found immediately after the codon for G143. A mutation for fungicide resistance at this location would hinder splicing and severely reduce fitness. B. oryzae expresses an alternative oxidase in vitro, which allows the fungus to survive inhibition of respiration by azoxystrobin. This research indicates that B. oryzae has not developed resistance to QoI fungicides, although monitoring for changes in sensitivity should be continued. Judicious use of QoI fungicides within an integrated disease management system will promote an effective and environmentally sound control of the pathogen in wild rice paddies.

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First Report of Postharvest Blue Mold decay caused by Penicillium expansum on Lemon (Citrus limon) fruit in China

Plant Disease ◽

10.1094/pdis-10-20-2239-pdn ◽

2021 ◽

Author(s):

Ibatsam Khokhar ◽

Jianming Chen ◽

Junhuan Wang ◽

Yang Jia ◽

Yanchun Yan ◽

...

Keyword(s):

Morphological Characteristics ◽

Its Region ◽

Penicillium Expansum ◽

Citrus Limon ◽

Conidial Suspension ◽

Blue Mold ◽

Causal Organism ◽

Lemon Fruit ◽

First Report ◽

Fungal Isolates

Lemon (Citrus limon) is one of the most important commercial (both dried and fresh) citrus fruits in China. In the spring of 2019, postharvest blue mold decay was observed at an incidence of 3-5% on lemon fruit at the local markets in Beijing, China. Fruit lesions were circular, brown, soft, and watery, and rapidly expanded at 25°C. To isolate the causal organism, small pieces (2 mm3) were cut from the lesions, surface-sterilized for 1 min in 1.5% NaOCl, rinsed three times with sterilized water, dried with sterile filter paper, placed onto potato dextrose agar (PDA) medium, and incubated at 25°C for 6 days. Eight morphologically similar single-colony fungal isolates were recovered from six lemon fruit. Colony surfaces were bluish-green on the upper surface and cream to yellow-brown one the reverse. Hyphae on colony margins were entirely subsurface and cream in color. Mycelium was highly branched, septate, and colorless, and conidiophores were 250 to 450 × 3.0 to 4.0 µm in size. Stipe of conidiophores were smooth-walled, bearing terminal penicilli, typically terverticillate or less commonly birverticillate, rami occurring singly, 16 to 23 × 3.0 to 4.0 µm, metulae in 3 to 6, measuring 12 to 15 × 3.0 to 4.0 µm. Phialides were ampulliform to almost cylindrical, in verticils of 5 to 8, measuring 8 to 11 × 2.5 to 3.2 µm with collula. Conidia were smooth-walled, ellipsoidal, measuring 3.0 to 3.5 × 2.5 to 3.0 µm. According to morphological characteristics, the fungus was identified as Penicillium expansum (Visagie et al. 2014). For molecular identification, genomic DNA of eight fungal isolates was extracted, regions of the beta-tubulin (TUB), and calmodulin (CAL) genes and ITS region, were amplified using Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 primers respectively. Obtained sequences of all isolates were identical to sequences of the representative isolate YC-IK12, which was submitted in the GenBank. BLAST results of YC-IK12 sequences (ITS; MT856700: TUB; MT856958: CAL; MT856959) showed 98 to 100% similarity with P. expansum accessions (NR-077154, LN896428, JX141581). For pathogenicity tests, 10 μl of conidial suspension (10 × 105 conidia/ml) from seven-day-old YC-IK12 culture was inoculated using a sterilized needle into the surface of each five asymptomatic disinfected lemons. As a control, three lemons were inoculated using sterile distilled water. All inoculated lemons were placed in plastic containers and incubated at 25°C for 7 days. Decay lesions, identical to the original observations, developed on all inoculated lemons, while control lemons remained asymptomatic. Fungus re-isolated from the inoculated lemon was identified as P. expansum on the basis morphology and Bt2a/Bt2b, CAL-228F/ CAL-737, and ITS1/ITS4 sequences. Previously, Penicillium spp. including P. expansum have been reported as post-harvest pathogens on various Citrus spp. (Louw & Korsten 2015). However, P. digitatum has been reported on lemons and P. expansum has been reported on stored Kiwifruit (Actinidia arguta), Malus, and Pyrus species in China (Tai, 1979; Wang et al. 2015). To our knowledge, this is the first report of blue mold caused by P. expansum on lemons in China. References Louw, J. P., Korsten, L. 2015. Plant Dis. 99:21-30. Tai, F.L. 1979. Sylloge Fungorum Sinicorum. Sci. Press, Acad. Sin., Peking, 1527 pages. 8097 Visagie, C.M. et al. 2014. Studies. Mycol.78: 343. Wang, C. W. et al. 2015. Plant Dis. 99:1037.

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Potential Application of Propolis Extracts to Control the Growth of Stemphylium vesicarium in “Rocha” Pear

Applied Sciences ◽

10.3390/app10061990 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1990 ◽

Cited By ~ 1

Author(s):

Marcella Loebler ◽

Claudia Sánchez ◽

Elisabete Muchagato Maurício ◽

Eugénio Diogo ◽

Mário Santos ◽

...

Keyword(s):

Disease Incidence ◽

Brown Spot ◽

In Vitro Assays ◽

Economic Losses ◽

Yield Reduction ◽

Stemphylium Vesicarium ◽

Spot Disease ◽

Brown Spot Disease

Stemphylium vesicarium (Wallr.) E. G. Simmons is the pathogen responsible of brown spot disease in pear and has become one of the main concerns for European pear producers. In Portugal, S. vesicarium is responsible for significant yield reduction and economic losses in “Rocha” pear (Pyrus communis L. cv Rocha) production. Considering the antimicrobial potential of propolis, the high incidence of brown spot in pears and the emergence of fungicides resistance in S. vesicarium, this study aimed to evaluate the potential of Portuguese propolis as an alternative strategy to control brown spot disease in “Rocha” pear. In vitro assays showed that propolis extracts were able to inhibit up to 90% the S. vesicarium mycelial growth. In vivo assays in artificially wounded and inoculated “Rocha” pears showed that, compared to the control, the disease incidence decreased up to 25% and the lesions diameter up to 57%, in fruits treated with propolis. Moreover, propolis seems to be more efficient in reducing the disease incidence when applied after pathogen inoculation (curative assay) than when applied before pathogen inoculation (prophylactic assay). Thus, the results suggest that propolis extracts have potential to be applied as part of an integrated approach for the control of brown spot of pear.

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Use ofMetarhizium anisopliaeChitinase Genes for Genotyping and Virulence Characterization

BioMed Research International ◽

10.1155/2013/465213 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Saliou Niassy ◽

Sevgan Subramanian ◽

Sunday Ekesi ◽

Joel L. Bargul ◽

Jandouwe Villinger ◽

...

Keyword(s):

Dna Sequences ◽

Critical Role ◽

Fungal Virulence ◽

Fungal Isolates ◽

Genetic Mechanisms ◽

Chitinase Production ◽

Chitinase Genes ◽

Selection Of

Virulence is the primary factor used for selection of entomopathogenic fungi (EPF) for development as biopesticides. To understand the genetic mechanisms underlying differences in virulence of fungal isolates on various arthropod pests, we compared the chitinase genes,chi2andchi4, of 8 isolates ofMetarhizium anisopliae. The clustering of the isolates showed various groups depending on their virulence. However, the analysis of their chitinase DNA sequenceschi2andchi4did not reveal major divergences. Although their protein translates have been implicated in fungal virulence, the predicted protein structure ofchi2was identical for all isolates. Despite the critical role of chitin digestion in fungal infection, we conclude thatchi2andchi4genes cannot serve as molecular markers to characterize observed variations in virulence amongM. anisopliaeisolates as previously suggested. Nevertheless, processes controlling the efficient upregulation of chitinase expression might be responsible for different virulence characteristics. Further studies using comparative “in vitro” chitin digestion techniques would be more appropriate to compare the quality and the quantity of chitinase production between fungal isolates.

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Isolation of native entomopathogenic fungi with potential for control of the pepper weevil, Anthonomus eugenii Cano, in Puerto Rico

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v101i1.14296 ◽

2021 ◽

Vol 101 (1) ◽

pp. 91-106

Author(s):

Miguel A. García-Carrucini ◽

Víctor Cartín Leyva ◽

Consuelo Estévez de Jensen

Keyword(s):

Puerto Rico ◽

Entomopathogenic Fungi ◽

Dna Sequences ◽

Integrated Management ◽

Management Program ◽

Mortality Data ◽

Anthonomus Eugenii ◽

Fungal Isolates ◽

Pepper Weevil

Entomopathogenic fungi were isolated parasitizing coffee borer beetle (Hypothenemus hampei Ferrari) and banana weevils (Cosmopolites sordidus Germar) in different parts of the island of Puerto Rico to be identified and examined for their pathogenicity on pepper weevil (Anthonomus eugenii Cano). Fungi were isolated and purified in acidulated potato dextroseagar (PDA) in the laboratory of the Plant Disease Clinic at the Agricultural Experiment Station, Juana Díaz. Seven fungal isolates were obtained from the municipality of Comerío, and one from the municipality of Adjuntas. Morphology, DNA sequences of different genetic regions of interest, and microsatellites were used for identification of fungal isolates. Two of the eight isolates were identified as Beauveria bassiana, three as Beauveria caledonica, two as Paecilomyces fumosorosea and one as Paecilomyces lilacinum. Pathogenicity tests were conducted in vitro using conidia suspension (1 x 106 conidia/mL). Insects were inoculated by immersion (10 sec) in the conidia suspension. Daily mortality data was taken (TL50, TL90) and the mean of the treatments were determined. All the fungal species were pathogenic to A. eugenii. The most effective treatments were: P. fumosorosea (Pae1) and B. bassiana (Bb1 & Bb3) with TL50 of 2.39, 2.53 and 2.56 days, respectively, while TL50 for the control was 6.56. A 100% mortality for treatments occurred between the fourth and sixth day compared to control, which reached it in 12 days. These isolates have the potential to be used on an integrated management program for the control of the pepper weevil.

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