scholarly journals Origin of agricultural plant pathogens: Diversity and pathogenicity of Rhizoctonia fungi associated with native prairie grasses in the Sandhills of Nebraska

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249335
Author(s):  
Srikanth Kodati ◽  
Anthony O. Adesemoye ◽  
Gary Y. Yuen ◽  
Jerry D. Volesky ◽  
Sydney E. Everhart
Keyword(s):  
Disease Severity ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Native Grasses ◽  
Agricultural Plant ◽  
Native Prairie ◽  
Little Bluestem ◽  
Complex Ecosystem ◽  
Greenhouse Assay ◽  
Sand Bluestem

The Sandhills of Nebraska is a complex ecosystem, covering 50,000 km2 in central and western Nebraska and predominantly of virgin grassland. Grasslands are the most widespread vegetation in the U.S. and once dominated regions are currently cultivated croplands, so it stands to reason that some of the current plant pathogens of cultivated crops originated from grasslands, particularly soilborne plant pathogens. The anamorphic genus Rhizoctonia includes genetically diverse organisms that are known to be necrotrophic fungal pathogens, saprophytes, mycorrhiza of orchids, and biocontrol agents. This study aimed to evaluate the diversity of Rhizoctonia spp. on four native grasses in the Sandhills of Nebraska and determine pathogenicity to native grasses and soybean. In 2016 and 2017, a total of 84 samples were collected from 11 sites in the Sandhills, located in eight counties of Nebraska. The samples included soil and symptomatic roots from the four dominant native grasses: sand bluestem, little bluestem, prairie sandreed, and needle-and-thread. Obtained were 17 Rhizoctonia-like isolates identified, including five isolates of binucleate Rhizoctonia AG-F; two isolates each from binucleate Rhizoctonia AG-B, AG-C, and AG-K, Rhizoctonia solani AGs: AG-3, and AG-4; one isolate of binucleate Rhizoctonia AG-L, and one isolate of R. zeae. Disease severity was assessed for representative isolates of each AG in a greenhouse assay using sand bluestem, needle-and-thread, and soybean; prairie sandreed and little bluestem were unable to germinate under artificial conditions. On native grasses, all but two isolates were either mildly aggressive (causing 5–21% disease severity) or aggressive (21–35% disease severity). Among those, three isolates were cross-pathogenic on soybean, with R. solani AG-4 shown to be highly aggressive (86% disease severity). Thus, it is presumed that Rhizoctonia spp. are native to the sandhills grasslands and an emerging pathogen of crops cultivated may have survived in the soil and originate from grasslands.

scholarly journals Susceptibility of Schlumbergera truncata Cultivars to Four Plant Pathogens

1993 ◽  
Vol 11 (1) ◽  
pp. 14-16 ◽  
Author(s):  
A.R. Chase ◽  
Jeanne M.F. Yuen
Keyword(s):  
Fusarium Oxysporum ◽  
Disease Severity ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Bacterial Pathogen ◽  
Erwinia Carotovora ◽  
Phytophthora Parasitica ◽  
Low Levels

Abstract Susceptibility of 20 cultivars of holiday cacti (Schlumbergera truncata) to three fungal pathogens (Drechslera cactivora, Fusarium oxysporum, and Phytophthora parasitica) and one bacterial pathogen (Erwinia carotovora subsp. carotovora) was evaluated. Significant differences in disease severity among cultivars occurred in 11 of the 12 tests with some cultivars responding consistently to one or more pathogens. ‘Gold Charm’ was highly susceptible to all four pathogens tested. ‘White Christmas’ developed low levels of disease when inoculated with either D. cactivora or E. carotovora subsp. carotovora but intermediate levels when inoculated with F. oxysporum or P. parasitica. ‘Peach Parfait’ showed one of the lowest levels of resistance to D. cactivora but one of the highest levels of resistance to F. oxysporum. Other cultivars showed intermediate disease responses; however, results were not consistent.

Identifying Native Prairie Grass Seedlings

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 450e-451
Author(s):  
Virginia A. Gaynor ◽  
Mary Hockenberry Meyer
Keyword(s):  
Panicum Virgatum ◽  
Schizachyrium Scoparium ◽  
Sorghastrum Nutans ◽  
Native Prairie ◽  
Switch Grass ◽  
Little Bluestem ◽  
Prairie Grass ◽  
Central United States ◽  
Prairie Restorations ◽  
Sideoats Grama

There is great interest in prairie gardens and prairie restorations in the central United States. Small prairie gardens are often established with plugs, but most restorationists and landscape contractors use seed for large plantings. If initial establishment is poor, restorations are often interseeded the second or third season. However, to evaluate early establishment and determine if interseeding is necessary, contractors must be able to identify native grasses in the seedling and juvenile stages. In this study we investigated vegetative characteristics of native prairie grass seedlings. Seven species of native prairie grass were grown in the greenhouse: Andropogon gerardii (big bluestem), Sorghastrum nutans (Indian grass), Panicum virgatum (switch grass), Schizachyrium scoparium (little bluestem), Bouteloua curtipendula (sideoats grama), Elymus canadensis (Canada wildrye), and Bromus kalmii (Kalmís brome). Every 2 to 3 weeks after germination, seedlings were photographed, pressed, and mounted. Additional photographs were taken through the dissecting scope at key stages of development. Ligules and auricles were found to be useful in distinguishing species, and our close-up photographs highlight these structures. Hairiness and color were variable within a species and could not be used reliably in identification. A seedling identification key will be presented for the species studied.

scholarly journals The Potential of Rhizoctonia-Like Fungi for the Biological Protection of Cereals against Fungal Pathogens

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 349
Author(s):  
Dominik Bleša ◽  
Pavel Matušinský ◽  
Romana Sedmíková ◽  
Milan Baláž
Keyword(s):  
Biological Control ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Higher Plants ◽  
Fusarium Culmorum ◽  
Suppressive Effect ◽  
Plant Production ◽  
Shoot Biomass ◽  
Organic Substrates

The use of biological control is becoming a common practice in plant production. One overlooked group of organisms potentially suitable for biological control are Rhizoctonia-like (Rh-like) fungi. Some of them are capable of forming endophytic associations with a large group of higher plants as well as mycorrhizal symbioses. Various benefits of endophytic associations were proved, including amelioration of devastating effects of pathogens such as Fusarium culmorum. The advantage of Rh-like endophytes over strictly biotrophic mycorrhizal organisms is the possibility of their cultivation on organic substrates, which makes their use more suitable for production. We focused on abilities of five Rh-like fungi isolated from orchid mycorrhizas, endophytic fungi Serendipita indica, Microdochium bolleyi and pathogenic Ceratobasidium cereale to inhibit the growth of pathogenic F. culmorum or Pyrenophora teres in vitro. We also analysed their suppressive effect on wheat infection by F. culmorum in a growth chamber, as well as an effect on barley under field conditions. Some of the Rh-like fungi affected the growth of plant pathogens in vitro, then the interaction with plants was tested. Beneficial effect was especially noted in the pot experiments, where wheat plants were negatively influenced by F. culmorum. Inoculation with S. indica caused higher dry shoot biomass in comparison to plants treated with fungicide. Prospective for future work are the effects of these endophytes on plant signalling pathways, factors affecting the level of colonization and surviving of infectious particles.

scholarly journals The Ustilago hordei–Barley Interaction is a Versatile System for Characterization of Fungal Effectors

2021 ◽  
Vol 7 (2) ◽  
pp. 86
Author(s):  
Bilal Ökmen ◽  
Daniela Schwammbach ◽  
Guus Bakkeren ◽  
Ulla Neumann ◽  
Gunther Doehlemann
Keyword(s):  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Expression System ◽  
Pathogenic Fungi ◽  
Effector Proteins ◽  
Mating Partner ◽  
Fungal Virulence ◽  
Functional Studies ◽  
Infection Structures ◽  
Ustilago Hordei

Obligate biotrophic fungal pathogens, such as Blumeria graminis and Puccinia graminis, are amongst the most devastating plant pathogens, causing dramatic yield losses in many economically important crops worldwide. However, a lack of reliable tools for the efficient genetic transformation has hampered studies into the molecular basis of their virulence or pathogenicity. In this study, we present the Ustilago hordei–barley pathosystem as a model to characterize effectors from different plant pathogenic fungi. We generate U. hordei solopathogenic strains, which form infectious filaments without the presence of a compatible mating partner. Solopathogenic strains are suitable for heterologous expression system for fungal virulence factors. A highly efficient Crispr/Cas9 gene editing system is made available for U. hordei. In addition, U. hordei infection structures during barley colonization are analyzed using transmission electron microscopy, showing that U. hordei forms intracellular infection structures sharing high similarity to haustoria formed by obligate rust and powdery mildew fungi. Thus, U. hordei has high potential as a fungal expression platform for functional studies of heterologous effector proteins in barley.

Potential New Herbicides – Phytotoxins from Plant Pathogens

1988 ◽  
Vol 2 (4) ◽  
pp. 519-524 ◽  
Author(s):  
Doug Kenfield ◽  
Greg Bunkers ◽  
Gary A. Strobel ◽  
Fumio Sugawara
Keyword(s):  
Organic Synthesis ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Biological Activities ◽  
Biological Data

A rationale for the study of phytotoxins from fungal pathogens of plants is presented. Structural chemistries and biological data are given for numerous, recently discovered phytotoxins in such diverse chemical classes as polyketides, terpenoids, diketopiperazines, and isocoumarins. The biological activities of these compounds range from broadly toxic (curvulin) to host specific (maculosin-1). Phytotoxicology offers a viable supplement to organic synthesis as a means of developing and implementing new, biorational, and economical herbicides.

Efficacy of Different Level of Systemic Fungicides on Management of Rice Blast at Baitadi, Nepal

2020 ◽  
Vol 7 ◽  
pp. 33-42
Author(s):  
Ashok Acharya ◽  
Prabin Ghimire ◽  
Dhurba Raj Joshi ◽  
Kishor Shrestha ◽  
Govinda Sijapati ◽  
...  
Keyword(s):  
Disease Severity ◽  
Rice Blast ◽  
Fungal Pathogens ◽  
Block Design ◽  
Rice Variety ◽  
Disease Suppression ◽  
Systemic Fungicide ◽  
Disease Development ◽  
Systemic Fungicides ◽  
Different Levels

Rice blast (Pyriculariaoryzae Cavara) is one of the most devastating diseases affecting the rice crop in across the world. Systemic fungicides are used for the suppression of blast diseases caused by fungal pathogens. Propiconazole and Carbendazim are commercial chemical control products available in markets for the control of the fungal pathogen. An experiment was conducted to examine the effectiveness of systemic fungicide on suppression of rice blast incidence in farmers' field during wet seasons in 2016. The treatments consisted of the use of different levels of propiconazole and Carbendazim on ‘Rato Basmati’ a landrace rice variety. The experiments were arranged in a randomized complete block design with three replications. The disease was scored according to the standard scale developed by the International Rice Research Institute (IRRI). Disease severity and Area under Disease Progressive curve (AUDPC) was computed based on that scale score. Propiconazole and Carbendazim at different levels reduce disease development than no treatment (control). But its efficacy was not consistent. The magnitude of disease suppression by Propiconazole was high as compared to Carbendazim. The application of propiconazole at the rate of 1.5 ml effectively reduced disease severity and AUDPC at different dates. So propiconazole at the rate of 1.5 ml thrice at weekly intervals is effective to reduce the disease development

scholarly journals The emergence of cereal fungal diseases and the incidence of leaf spot diseases in Finland

2008 ◽  
Vol 20 (1) ◽  
pp. 62 ◽  
Author(s):  
M. JALLI ◽  
P. LAITINEN ◽  
S. LATVALA
Keyword(s):  
Spring Wheat ◽  
Leaf Spot ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Field Survey ◽  
Fungal Diseases ◽  
Cochliobolus Sativus ◽  
Pyrenophora Tritici Repentis ◽  
Fungal Plant Pathogens ◽  
First Time

Fungal plant pathogens causing cereal diseases in Finland have been studied by a literature survey, and a field survey of cereal leaf spot diseases conducted in 2009. Fifty-seven cereal fungal diseases have been identified in Finland. The first available references on different cereal fungal pathogens were published in 1868 and the most recent reports are on the emergence of Ramularia collo-cygni and Fusarium langsethiae in 2001. The incidence of cereal leaf spot diseases has increased during the last 40 years. Based on the field survey done in 2009 in Finland, Pyrenophora teres was present in 86%, Cochliobolus sativus in 90% and Rhynchosporium secalis in 52% of the investigated barley fields. Mycosphaerella graminicola was identified for the first time in Finnish spring wheat fields, being present in 6% of the studied fields. Stagonospora nodorum was present in 98% and Pyrenophora tritici-repentis in 94% of spring wheat fields. Oat fields had the fewest fungal diseases. Pyrenophora chaetomioides was present in 63% and Cochliobolus sativus in 25% of the oat fields studied.;

scholarly journals The Potential Use of Isothermal Amplification Assays for In-Field Diagnostics of Plant Pathogens

Plants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2424
Author(s):  
Aleksandr V. Ivanov ◽  
Irina V. Safenkova ◽  
Anatoly V. Zherdev ◽  
Boris B. Dzantiev
Keyword(s):  
Molecular Diagnostics ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Isothermal Amplification ◽  
Detection Methods ◽  
Nucleic Acid Detection ◽  
Advantages And Disadvantages ◽  
Fungal Phytopathogens ◽  
Highly Sensitive Detection ◽  
And Control

Rapid, sensitive, and timely diagnostics are essential for protecting plants from pathogens. Commonly, PCR techniques are used in laboratories for highly sensitive detection of DNA/RNA from viral, viroid, bacterial, and fungal pathogens of plants. However, using PCR-based methods for in-field diagnostics is a challenge and sometimes nearly impossible. With the advent of isothermal amplification methods, which provide amplification of nucleic acids at a certain temperature and do not require thermocyclic equipment, going beyond the laboratory has become a reality for molecular diagnostics. The amplification stage ceases to be limited by time and instruments. Challenges to solve involve finding suitable approaches for rapid and user-friendly plant preparation and detection of amplicons after amplification. Here, we summarize approaches for in-field diagnostics of phytopathogens based on different types of isothermal amplification and discuss their advantages and disadvantages. In this review, we consider a combination of isothermal amplification methods with extraction and detection methods compatible with in-field phytodiagnostics. Molecular diagnostics in out-of-lab conditions are of particular importance for protecting against viral, bacterial, and fungal phytopathogens in order to quickly prevent and control the spread of disease. We believe that the development of rapid, sensitive, and equipment-free nucleic acid detection methods is the future of phytodiagnostics, and its benefits are already visible.

scholarly journals RNAi of a Putative Grapevine Susceptibility Gene as a Possible Downy Mildew Control Strategy

2021 ◽  
Vol 12 ◽  
Author(s):  
Demetrio Marcianò ◽  
Valentina Ricciardi ◽  
Elena Marone Fassolo ◽  
Alessandro Passera ◽  
Piero Attilio Bianco ◽  
...  
Keyword(s):  
Gene Expression ◽  
Downy Mildew ◽  
Disease Severity ◽  
Fungal Pathogens ◽  
Management Strategies ◽  
Susceptibility Gene ◽  
Plasmopara Viticola ◽  
Pinot Noir ◽  
Economic Losses ◽  
Reproductive Structures

Downy mildew, caused by the oomycete Plasmopara viticola, is one of the diseases causing the most severe economic losses to grapevine (Vitis vinifera) production. To date, the application of fungicides is the most efficient method to control the pathogen and the implementation of novel and sustainable disease control methods is a major challenge. RNA interference (RNAi) represents a novel biotechnological tool with a great potential for controlling fungal pathogens. Recently, a candidate susceptibility gene (VviLBDIf7) to downy mildew has been identified in V. vinifera. In this work, the efficacy of RNAi triggered by exogenous double-stranded RNA (dsRNA) in controlling P. viticola infections has been assessed in a highly susceptible grapevine cultivar (Pinot noir) by knocking down VviLBDIf7 gene. The effects of dsRNA treatment on this target gene were assessed by evaluating gene expression, disease severity, and development of vegetative and reproductive structures of P. viticola in the leaf tissues. Furthermore, the effects of dsRNA treatment on off-target (EF1α, GAPDH, PEPC, and PEPCK) and jasmonic acid metabolism (COI1) genes have been evaluated. Exogenous application of dsRNA led to significant reductions both in VviLBDIf7 gene expression, 5 days after the treatment, and in the disease severity when artificial inoculation was carried out 7 days after dsRNA treatments. The pathogen showed clear alterations to both vegetative (hyphae and haustoria) and reproductive structures (sporangiophores) that resulted in stunted growth and reduced sporulation. Treatment with dsRNA showed signatures of systemic activity and no deleterious off-target effects. These results demonstrated the potential of RNAi for silencing susceptibility factors in grapevine as a sustainable strategy for pathogen control, underlying the possibility to adopt this promising biotechnological tool in disease management strategies.

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