scholarly journals Ecological Dynamics and Microbial Treatments against Oomycete Plant Pathogens

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2697
Author(s):  
Karen E. Sullam ◽  
Tomke Musa

In this review, we explore how ecological concepts may help assist with applying microbial biocontrol agents to oomycete pathogens. Oomycetes cause a variety of agricultural diseases, including potato late blight, apple replant diseases, and downy mildew of grapevine, which also can lead to significant economic damage in their respective crops. The use of microbial biocontrol agents is increasingly gaining interest due to pressure from governments and society to reduce chemical plant protection products. The success of a biocontrol agent is dependent on many ecological processes, including the establishment on the host, persistence in the environment, and expression of traits that may be dependent on the microbiome. This review examines recent literature and trends in research that incorporate ecological aspects, especially microbiome, host, and environmental interactions, into biological control development and applications. We explore ecological factors that may influence microbial biocontrol agents’ efficacy and discuss key research avenues forward.

Author(s):  
Mihaela Ursan ◽  
Oana Alina Boiu-Sicuia ◽  
Cătălina Voaides ◽  
Vasilica Stan ◽  
Corina Bubueanu ◽  
...  

Abstract The excessive use of synthetic pesticides for plant pathogens control could cause possible harmful side-effects to humans and animals, environmental pollution, residual toxicity, affects soil characteristics or induce the development of fungal resistance. Alternative ways for fungal contamination control involve natural products, based on microorganisms, many of them being already available for use. The selection and characterization of new biological agents useful for plant pathogens control are permanent goals for plant protection researches. In the last decade, several studies revealed that Streptomyces species are promising biocontrol agents against a wide range of phytopathogenic fungi, including Fusarium spp., one of the most important wheat pathogens. In our study, 60 strains of Streptomyces spp. were isolated from soil or compost and evaluated for in vitro antifungal abilities by dual confrontation method. At least 30% of the isolates presented inhibitory activity against F. culmorum and F. graminearum. The bacterial strains were also tested for their ability to produce various bioactive compounds, possible involved in fungal inhibition. The capacity of some of the bacterial isolates to produce cellulases, amylases, lipases and volatile metabolites was proved. In addition, a new screening method for chitinases production was developed, based on the use of a combination of Congo red and Lugol solutions, which allowed the detection of chitinases in several Streptomyces spp. strains. Moreover, the reduction of the level of some Fusarium mycotoxins was detected by HPTLC analysis. As a conclusion, antagonistic interactions between Streptomyces isolates and fusaria could involve antibiosis, competition and parasitism and suggested that at least some of the selected isolates could be used in obtaining biological control products.


2019 ◽  
Vol 7 (8) ◽  
pp. 249 ◽  
Author(s):  
Houda Ben Slama ◽  
Mohamed Ali Triki ◽  
Ali Chenari Bouket ◽  
Fedia Ben Mefteh ◽  
Faizah N. Alenezi ◽  
...  

Halophyte Limoniastrum monopetalum, an evergreen shrub inhabiting the Mediterranean region, has well-documented phytoremediation potential for metal removal from polluted sites. It is also considered to be a medicinal halophyte with potent activity against plant pathogens. Therefore, L. monopetalum may be a suitable candidate for isolating endophytic microbiota members that provide plant growth promotion (PGP) and resistance to abiotic stresses. Selected for biocontrol abilities, these endophytes may represent multifaceted and versatile biocontrol agents, combining pathogen biocontrol in addition to PGP and plant protection against abiotic stresses. In this study 117 root culturable bacterial endophytes, including Gram-positive (Bacillus and Brevibacillus), Gram-negative (Proteus, Providencia, Serratia, Pantoea, Klebsiella, Enterobacter and Pectobacterium) and actinomycete Nocardiopsis genera have been recovered from L. monopetalum. The collection exhibited high levels of biocontrol abilities against bacterial (Agrobacterium tumefaciens MAT2 and Pectobacterium carotovorum MAT3) and fungal (Alternaria alternata XSZJY-1, Rhizoctonia bataticola MAT1 and Fusarium oxysporum f. sp. radicis lycopersici FORL) pathogens. Several bacteria also showed PGP capacity and resistance to antibiotics and metals. A highly promising candidate Bacillus licheniformis LMRE 36 with high PGP, biocontrol, metal and antibiotic, resistance was subsequently tested in planta (potato and olive trees) for biocontrol of a collection of 14 highly damaging Fusarium species. LMRE 36 proved very effective against the collection in both species and against an emerging Fusarium sp. threatening olive trees culture in nurseries. These findings provide a demonstration of our pyramiding strategy. Our strategy was effective in combining desirable traits in biocontrol agents towards broad-spectrum resistance against pathogens and protection of crops from abiotic stresses. Stacking multiple desirable traits into a single biocontrol agent is achieved by first, careful selection of a host for endophytic microbiota recovery; second, stringent in vitro selection of candidates from the collection; and third, application of the selected biocontrol agents in planta experiments. That pyramiding strategy could be successfully used to mitigate effects of diverse biotic and abiotic stresses on plant growth and productivity. It is anticipated that the strategy will provide a new generation of biocontrol agents by targeting the microbiota of plants in hostile environments.


Foods ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1418
Author(s):  
Caroline De Clerck ◽  
Simon Dal Maso ◽  
Olivier Parisi ◽  
Frédéric Dresen ◽  
Abdesselam Zhiri ◽  
...  

Nowadays, the demand for a reduction of chemical pesticides use is growing. In parallel, the development of alternative methods to protect crops from pathogens and pests is also increasing. Essential oil (EO) properties against plant pathogens are well known, and they are recognized as having an interesting potential as alternative plant protection products. In this study, 90 commercially available essential oils have been screened in vitro for antifungal and antibacterial activity against 10 plant pathogens of agronomical importance. EOs have been tested at 500 and 1000 ppm, and measures have been made at three time points for fungi (24, 72 and 120 h of contact) and every two hours for 12 h for bacteria, using Elisa microplates. Among the EOs tested, the ones from Allium sativum, Corydothymus capitatus, Cinnamomum cassia, Cinnamomum zeylanicum, Cymbopogon citratus, Cymbopogon flexuosus, Eugenia caryophyllus, and Litsea citrata were particularly efficient and showed activity on a large panel of pathogens. Among the pathogens tested, Botrytis cinerea, Fusarium culmorum, and Fusarium graminearum were the most sensitive, while Colletotrichum lindemuthianum and Phytophthora infestans were the less sensitive. Some EOs, such as the ones from A. sativum, C. capitatus, C. cassia, C. zeylanicum, C. citratus, C. flexuosus, E. caryophyllus, and L. citrata, have a generalist effect, and are active on several pathogens (7 to 10). These oils are rich in phenols, phenylpropanoids, organosulfur compounds, and/or aldehydes. Others, such as EOs from Citrus sinensis, Melaleucacajputii, and Vanilla fragrans, seem more specific, and are only active on one to three pathogens. These oils are rich in terpenes and aldehydes.


2022 ◽  
Author(s):  
Stéphane Pesce ◽  
Annette Bérard ◽  
Marie-Agnès Coutellec ◽  
Alexandra Langlais-Hesse ◽  
Mickaël Hedde ◽  
...  

There is growing interest in using the ecosystem services framework for environmental risk assessments of plant protection products (PPP). However, there is still a broad gap between most of the ecotoxicological endpoints used in PPP risk assessment and the evaluation of the risks and effects of PPP on ecosystem services. Here we propose a conceptual framework to link current and future knowledge on the ecotoxicological effects of PPP on biodiversity and ecological processes to their consequences on ecosystem functions and services. We first describe the main processes governing the relationships between biodiversity, ecological processes and ecosystem functions in response to effects of PPP. We define 12 main categories of ecosystem functions that could be directly linked with the ecological processes used as functional endpoints in investigations on the ecotoxicology of PPP. An exploration of perceptions on the possible links between these categories of ecosystem functions and groups of ecosystem services (by a panel scientific experts in various fields of environmental sciences) then finds that these direct and indirect linkages still need clarification. We illustrate how the proposed framework could be used on terrestrial microalgae and cyanobacteria to assess the potential effects of herbicides on ecosystem services. The framework proposed here uses a set of clearly-defined core categories of ecosystem functions and services, which should help identify which of them are effectively or potentially threatened by PPP. We argue that this framework could help harmonize and extend the scientific knowledge that informs decision-making and policy-making.


Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 701 ◽  
Author(s):  
Sabrina Sarrocco ◽  
Antonio Mauro ◽  
Paola Battilani

Among plant fungal diseases, those affecting cereals represent a huge problem in terms of food security and safety. Cereals, such as maize and wheat, are very often targets of mycotoxigenic fungi. The limited availability of chemical plant protection products and physical methods to control mycotoxigenic fungi and to reduce food and feed mycotoxin contamination fosters alternative approaches, such as the use of beneficial fungi as an active ingredient of biological control products. Competitive interactions, including both exploitation and interference competition, between pathogenic and beneficial fungi, are generally recognized as mechanisms to control plant pathogens populations and to manage plant diseases. In the present review, two examples concerning the use of competitive beneficial filamentous fungi for the management of cereal diseases are discussed. The authors retrace the history of the well-established use of non-aflatoxigenic isolates of Aspergillus flavus to prevent aflatoxin contamination in maize and give an overview of the potential use of competitive beneficial filamentous fungi to manage Fusarium Head Blight on wheat and mitigate fusaria toxin contamination. Although important steps have been made towards the development of microorganisms as active ingredients of plant protection products, a reasoned revision of the registration rules is needed to significantly reduce the chemical based plant protection products in agriculture.


2021 ◽  
pp. 103-122
Author(s):  
Marc Bardin ◽  
◽  
Thomas Pressecq ◽  
Philippe C. Nicot ◽  
Yousra Bouaoud ◽  
...  

Plant pathogens can develop resistance to conventional plant protection products but their ability to overcome the effect of microbial bioprotectants is still poorly known. However, various studies show that susceptibility of plant pathogens to microbial bioprotectants can be highly variable. This may contribute to the inconsistent efficacy of microbial bioprotectants sometimes observed in the field. An important question is whether the widespread use of microbial bioprotectants in the field could conduct to the selection of even more resistant phenotypes of plant pathogens. This chapter highlights current knowledge concerning erosion of microbial bioprotectants against plant pathogens and its possible consequences for field efficacy.


2020 ◽  
Vol 21 (24) ◽  
pp. 9361
Author(s):  
Michał Pylak ◽  
Karolina Oszust ◽  
Magdalena Frąc

The threat caused by plants fungal and fungal-like pathogens is a serious problem in the organic farming of soft fruits. The European Commission regulations prohibit some commercially available chemical plant protection products, and instead recommend the use of natural methods for improving the microbial soil status and thus increasing resistance to biotic stresses caused by phytopathogens. The solution to this problem may be biopreparations based on, e.g., bacteria, especially those isolated from native local environments. To select proper bacterial candidates for biopreparation, research was provided to preliminarily ensure that those isolates are able not only to inhibit the growth of pathogens, but also to be metabolically effective. In the presented research sixty-five isolates were acquired and identified. Potentially pathogenic isolates were excluded from further research, and beneficial bacterial isolates were tested against the following plant pathogens: Botrytis spp., Colletotrichum spp., Phytophthora spp., and Verticillium spp. The eight most effective antagonists belonging to Arthrobacter, Bacillus, Pseudomonas, and Rhodococcus genera were subjected to metabolic and enzymatic analyses and a resistance to chemical stress survey, indicating to their potential as components of biopreparations for agroecology.


2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Pradeep Kumar ◽  
Shikha Pandhi ◽  
Dipendra Kumar Mahato ◽  
Madhu Kamle ◽  
Archana Mishra

Abstract Background Recent concerns linked with the application of chemical pesticides and the increasing necessity of low inputs sustainable agriculture have put the use of microbial biocontrol agents and bio-pesticides to the forefront for their application against plant pathogens and insect–pest management. Results This review tended to scrutinize the prospects of microbial biocontrol agents and microbes-based nano-formulations against plant diseases and for pest management with emphasis on bacteria-based nanoparticles, especially derived from Bacillus species. It also tended to discuss the probable mechanism of action and effect on plant growth along with its prospects in a brief manner. Conclusion The use of microbial biocontrol agents offers effective, eco-friendly, and long-lasting management of plant diseases. The employment of nanotechnology in the field of biopesticides has emerged as a promising solution. Nano-biopesticides in the form of biologically derived active pesticides or compounds integrated as nanoparticles and integrated into a suitable polymer have application in insect–pest management.


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