Journal articles: 'Genetic biocontrol'

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Hermosa, M. Rosa, Emma Keck, Isabel Chamorro, Belén Rubio, Luis Sanz, Juan A. Vizcaíno, Isabel Grondona, and Enrique Monte. "Genetic diversity shown in Trichoderma biocontrol isolates." Mycological Research 108, no. 8 (August 2004): 897–906. http://dx.doi.org/10.1017/s0953756204000358.

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Kapuscinski, Anne R., and Leah M. Sharpe. "Introduction: genetic biocontrol of invasive fish species." Biological Invasions 16, no. 6 (April 3, 2014): 1197–200. http://dx.doi.org/10.1007/s10530-014-0681-6.

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Gilna, Ben, Jennifer Kuzma, and Stephanie Showalter Otts. "Governance of genetic biocontrol technologies for invasive fish." Biological Invasions 16, no. 6 (February 1, 2013): 1299–312. http://dx.doi.org/10.1007/s10530-012-0367-x.

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Mukherjee, Prasun K., and Charles M. Kenerley. "Regulation of Morphogenesis and Biocontrol Properties in Trichoderma virens by a VELVET Protein, Vel1." Applied and Environmental Microbiology 76, no. 7 (February 12, 2010): 2345–52. http://dx.doi.org/10.1128/aem.02391-09.

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ABSTRACT Mycoparasitic strains of Trichoderma are applied as commercial biofungicides for control of soilborne plant pathogens. Although the majority of commercial biofungicides are Trichoderma based, chemical pesticides, which are ecological and environmental hazards, still dominate the market. This is because biofungicides are not as effective or consistent as chemical fungicides. Efforts to improve these products have been limited by a lack of understanding of the genetic regulation of biocontrol activities. In this study, using gene knockout and complementation, we identified the VELVET protein Vel1 as a key regulator of biocontrol, as well as morphogenetic traits, in Trichoderma virens, a commercial biocontrol agent. Mutants with mutations in vel1 were defective in secondary metabolism (antibiosis), mycoparasitism, and biocontrol efficacy. In nutrient-rich media they also lacked two types of spores important for survival and development of formulation products: conidia (on agar) and chlamydospores (in liquid shake cultures). These findings provide an opportunity for genetic enhancement of biocontrol and industrial strains of Trichoderma, since Vel1 is very highly conserved across three Trichoderma species.

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Du, Yanru, Yuxian Xia, and Kai Jin. "Enhancing the Biocontrol Potential of the Entomopathogenic Fungus in Multiple Respects via the Overexpression of a Transcription Factor Gene MaSom1." Journal of Fungi 8, no. 2 (January 21, 2022): 105. http://dx.doi.org/10.3390/jof8020105.

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Entomopathogenic fungi play important roles in the control of populations of agricultural and disease vector pests in nature. The shortcomings of mycoinsecticides for pest management in the field cannot be completely overcome by improving single biocontrol properties of fungi. Therefore, enhancing the biocontrol potential of entomopathogenic fungi in multiple respects by genetic engineering is desirable. Transcription factors are usually involved in various important processes during fungal growth and pathogenesis via regulating a series of genes, and are important candidates for fungal improvement via genetic engineering. Herein, overexpression of MaSom1, a key transcription factor gene in the cAMP/PKA pathway, improves the biocontrol traits of Metarhizium acridum in multiple respects. When compared with WT, the MaSom1-overexpression strains exhibit enhanced tolerances to UV-B and heat shock, with increased mean 50% inhibition times by 66.9% and 155.2%, respectively. Advanced conidiation emerged accompanied by increased conidial yield up to 3.89 times after 3-day incubation for the MaSom1-overexpression strains compared to WT. Furthermore, when compared with WT, the virulence of the MaSom1-overexpression strains was also increased with the mean 50% lethality times reduced by 21.8% to 23.8%. Taken together, the MaSom1-overexpression improved the biocontrol potential of M. acridum in multiple respects. Our results provide insights into the application of key transcription factors for genetic engineering and offer a credible way to further improve the biocontrol potential of entomopathogenic fungi.

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Smith, Kevin P., Jo Handelsman, and Robert M. Goodman. "Modeling Dose-Response Relationships in Biological Control: Partitioning Host Responses to the Pathogen and Biocontrol Agent." Phytopathology® 87, no. 7 (July 1997): 720–29. http://dx.doi.org/10.1094/phyto.1997.87.7.720.

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Breeding plants to improve the effectiveness of biocontrol agents is a promising approach to enhance disease suppression by microorganisms. Differences in biocontrol efficacy among cultivars suggest there is genetic variation for this trait within crop germplasm. The ability to quantify host differences in support of biological control is influenced by variation in host response to the pathogen and the dose of pathogen and biocontrol agent applied to the host. To assess the contribution of each of these factors to successful biocontrol interactions, we measured disease over a range of pathogen (Pythium) and biocontrol agent (Bacillus cereus UW85) inoculum doses. We fit dose-response models to these data and used model parameter estimates to quantify host differences in response to the pathogen and biocontrol agent. We first inoculated eight plant species separately with three species of Pythium and evaluated three dose-response models for their ability to describe the disease response to pathogen inoculum level. All three models fit well to at least some of the host-pathogen combinations; the hyperbolic saturation model provided the best overall fit. To quantify the host contribution to biological control, we next evaluated these models with data from a tomato assay, using six inbred tomato lines, P. torulosum, and UW85. The lowest dose of pathogen applied revealed the greatest differences in seedling mortality among the inbred lines, ranging from 40 to 80%. The negative exponential (NE) pathogen model gave the best fit to these pathogen data, and these differences corresponded to model parameter values, which quantify pathogen efficiency, of 0.023 and 0.091. At a high pathogen dose, we detected the greatest differences in biocontrol efficacy among the inbred lines, ranging from no effect to a 68% reduction in mortality. The NE pathogen model with a NE biocontrol component, the NE/NE biocontrol model, gave the best fit to these biocontrol data, and these reductions corresponded to model parameter values, which quantify biocontrol efficiency, of 0.00 and 0.038, respectively. There was no correlation between the host response to the pathogen and biocontrol agent for these inbred lines. This work demonstrates the utility of epidemiological modeling approaches for the study of biological control and lays the groundwork to employ manipulation of host genetics to improve biocontrol efficacy.

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Afordoanyi, Daniel Mawuena, Roderic Gilles Claret Diabankana, Aynur Kamilevich Miftakhov, Evgenii Sergeyevich Kuchaev, and Shamil Zavdatovich Validov. "Genomic Features of Pseudomonas putida PCL1760: A Biocontrol Agent Acting via Competition for Nutrient and Niche." Applied Microbiology 2, no. 4 (October 2, 2022): 749–65. http://dx.doi.org/10.3390/applmicrobiol2040057.

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Pseudomonasputida strain PCL1760 is a biocontrol agent protecting plants from pathogens via the mechanism of competition for nutrients and niches (CNN). To confirm this mechanism as well as to adapt the strain for biotechnological applications, full genome analysis was compared with the known biotechnological model, P. putida S12, and other related species, which were analyzed on different genomic databases. Moreover, the antibacterial activity of PCL1760 was tested against Staphylococcus aureus, Pseudomonas aeruginosa, and Pseudomonas syringae. No genetic systems involved in antibiosis were revealed among the secondary metabolite clusters of the strain of PCL1760. The only antagonistic effect was observed against P. syringae, which might be because of siderophore (yellow-greenish fluorescence), although less than 19% pyoverdin biosynthesis clusters were predicted using the AntiSMASH server. P. putida PCL1760 in comparison with the Pseudomonas simiae strain PCL1751, another biocontrol agent acting solely via CNN, which lost its ‘luxury’ genes necessary for antibiosis or parasitism/predation mechanisms, but carries genetic systems providing motility. Interestingly, immunity genes (CRISPR/Cas and prophages) showed PCL1760 to be robust in comparison with S12, while annotation on OrthoVenn2 showed PCL1760 to be amenable for genetic manipulations. It is tempting to state that rhizobacteria using the mechanism of CNN are distinguishable from biocontrol agents acting via antibiosis or parasitism/predation at the genomic level. This confirms the CNN of PCL1760 as the sole mechanism for biocontrol and we suggest the strain as a new model for genetic engineering.

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Otts, Stephanie Showalter. "U.S. regulatory framework for genetic biocontrol of invasive fish." Biological Invasions 16, no. 6 (September 5, 2012): 1289–98. http://dx.doi.org/10.1007/s10530-012-0327-5.

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Sweany, Rebecca, Brian Mack, Geromy Moore, Matthew Gilbert, Jeffrey Cary, Matthew Lebar, Kanniah Rajasekaran, and Kenneth Damann. "Genetic Responses and Aflatoxin Inhibition during Co-Culture of Aflatoxigenic and Non-Aflatoxigenic Aspergillus flavus." Toxins 13, no. 11 (November 11, 2021): 794. http://dx.doi.org/10.3390/toxins13110794.

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Aflatoxin is a carcinogenic mycotoxin produced by Aspergillus flavus. Non-aflatoxigenic (Non-tox) A. flavus isolates are deployed in corn fields as biocontrol because they substantially reduce aflatoxin contamination via direct replacement and additionally via direct contact or touch with toxigenic (Tox) isolates and secretion of inhibitory/degradative chemicals. To understand touch inhibition, HPLC analysis and RNA sequencing examined aflatoxin production and gene expression of Non-tox isolate 17 and Tox isolate 53 mono-cultures and during their interaction in co-culture. Aflatoxin production was reduced by 99.7% in 72 h co-cultures. Fewer than expected unique reads were assigned to Tox 53 during co-culture, indicating its growth and/or gene expression was inhibited in response to Non-tox 17. Predicted secreted proteins and genes involved in oxidation/reduction were enriched in Non-tox 17 and co-cultures compared to Tox 53. Five secondary metabolite (SM) gene clusters and kojic acid synthesis genes were upregulated in Non-tox 17 compared to Tox 53 and a few were further upregulated in co-cultures in response to touch. These results suggest Non-tox strains can inhibit growth and aflatoxin gene cluster expression in Tox strains through touch. Additionally, upregulation of other SM genes and redox genes during the biocontrol interaction demonstrates a potential role of inhibitory SMs and antioxidants as additional biocontrol mechanisms and deserves further exploration to improve biocontrol formulations.

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Léger, Geneviève, Amy Novinscak, Adrien Biessy, Simon Lamarre, and Martin Filion. "In Tuber Biocontrol of Potato Late Blight by a Collection of Phenazine-1-Carboxylic Acid-Producing Pseudomonas spp." Microorganisms 9, no. 12 (December 7, 2021): 2525. http://dx.doi.org/10.3390/microorganisms9122525.

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Phenazine-1-carboxylic acid (PCA) produced by plant-beneficial Pseudomonas spp. is an antibiotic with antagonistic activities against Phytophthora infestans, the causal agent of potato late blight. In this study, a collection of 23 different PCA-producing Pseudomonas spp. was confronted with P. infestans in potato tuber bioassays to further understand the interaction existing between biocontrol activity and PCA production. Overall, the 23 strains exhibited different levels of biocontrol activity. In general, P. orientalis and P. yamanorum strains showed strong disease reduction, while P. synxantha strains could not effectively inhibit the pathogen’s growth. No correlation was found between the quantities of PCA produced and biocontrol activity, suggesting that PCA cannot alone explain P. infestans’ growth inhibition by phenazine-producing pseudomonads. Other genetic determinants potentially involved in the biocontrol of P. infestans were identified through genome mining in strains displaying strong biocontrol activity, including siderophores, cyclic lipopeptides and non-ribosomal peptide synthase and polyketide synthase hybrid clusters. This study represents a step forward towards better understanding the biocontrol mechanisms of phenazine-producing Pseudomonas spp. against potato late blight.

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Nelkner, Johanna, Gonzalo Torres Tejerizo, Julia Hassa, Timo Wentong Lin, Julian Witte, Bart Verwaaijen, Anika Winkler, et al. "Genetic Potential of the Biocontrol Agent Pseudomonas brassicacearum (Formerly P. trivialis) 3Re2-7 Unraveled by Genome Sequencing and Mining, Comparative Genomics and Transcriptomics." Genes 10, no. 8 (August 9, 2019): 601. http://dx.doi.org/10.3390/genes10080601.

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The genus Pseudomonas comprises many known plant-associated microbes with plant growth promotion and disease suppression properties. Genome-based studies allow the prediction of the underlying mechanisms using genome mining tools and the analysis of the genes unique for a strain by implementing comparative genomics. Here, we provide the genome sequence of the strain Pseudomonas brassicacearum 3Re2-7, formerly known as P. trivialis and P. reactans, elucidate its revised taxonomic classification, experimentally verify the gene predictions by transcriptome sequencing, describe its genetic biocontrol potential and contextualize it to other known Pseudomonas biocontrol agents. The P. brassicacearum 3Re2-7 genome comprises a circular chromosome with a size of 6,738,544 bp and a GC-content of 60.83%. 6267 genes were annotated, of which 6113 were shown to be transcribed in rich medium and/or in the presence of Rhizoctonia solani. Genome mining identified genes related to biocontrol traits such as secondary metabolite and siderophore biosynthesis, plant growth promotion, inorganic phosphate solubilization, biosynthesis of lipo- and exopolysaccharides, exoproteases, volatiles and detoxification. Core genome analysis revealed, that the 3Re2-7 genome exhibits a high collinearity with the representative genome for the species, P. brassicacearum subsp. brassicacearum NFM421. Comparative genomics allowed the identification of 105 specific genes and revealed gene clusters that might encode specialized biocontrol mechanisms of strain 3Re2-7. Moreover, we captured the transcriptome of P. brassicacearum 3Re2-7, confirming the transcription of the predicted biocontrol-related genes. The gene clusters coding for 2,4-diacetylphloroglucinol (phlABCDEFGH) and hydrogen cyanide (hcnABC) were shown to be highly transcribed. Further genes predicted to encode putative alginate production enzymes, a pyrroloquinoline quinone precursor peptide PqqA and a matrixin family metalloprotease were also found to be highly transcribed. With this study, we provide a basis to further characterize the mechanisms for biocontrol in Pseudomonas species, towards a sustainable and safe application of P. brassicacearum biocontrol agents.

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Harrop, Thomas W. R., Marissa F. Le Lec, Ruy Jauregui, Shannon E. Taylor, Sarah N. Inwood, Tracey van Stijn, Hannah Henry, et al. "Genetic Diversity in Invasive Populations of Argentine Stem Weevil Associated with Adaptation to Biocontrol." Insects 11, no. 7 (July 14, 2020): 441. http://dx.doi.org/10.3390/insects11070441.

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Modified, agricultural landscapes are susceptible to damage by insect pests. Biological control of pests is typically successful once a control agent has established, but this depends on the agent’s capacity to co-evolve with the host. Theoretical studies have shown that different levels of genetic variation between the host and the control agent will lead to rapid evolution of resistance in the host. Although this has been reported in one instance, the underlying genetics have not been studied. To address this, we measured the genetic variation in New Zealand populations of the pasture pest, Argentine stem weevil (Listronotus bonariensis), which is controlled with declining effectiveness by a parasitoid wasp, Microctonus hyperodae. We constructed a draft reference genome of the weevil, collected samples from a geographical survey of 10 sites around New Zealand, and genotyped them using a modified genotyping-by-sequencing approach. New Zealand populations of Argentine stem weevil have high levels of heterozygosity and low population structure, consistent with a large effective population size and frequent gene flow. This implies that Argentine stem weevils were able to evolve more rapidly than their biocontrol agent, which reproduces asexually. These findings show that monitoring genetic diversity in biocontrol agents and their targets is critical for long-term success of biological control.

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Weidemann, Gregory J., and David O. Tebeest. "Biology of Host Range Testing for Biocontrol of Weeds." Weed Technology 4, no. 3 (September 1990): 465–70. http://dx.doi.org/10.1017/s0890037x0002577x.

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The determination of host range is an important component in developing a plant pathogen for use as a bioherbicide. The safety of non-target economic and wild plants must be assured before experimental release and commercial use. In contrast to other methods of weed control, the genetic variability and genetic stability of both the weed and the biological control agent must be considered. Schemes to determine host range generally assume a close phylogenetic relationship between the weed host and its co-evolved pathogens. Therefore, testing generally is based on inoculation of genetically related plant species and progresses to more distantly related species until the host range is circumscribed. Several potential weaknesses in these schemes will be illustrated with examples using specific biological control agents. Future tests must place greater emphasis on testing taxa representing the full range of genetic diversity within the biogeographic area of intended use.

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Sharpe, Leah M. "Public perspectives on genetic biocontrol technologies for controlling invasive fish." Biological Invasions 16, no. 6 (September 14, 2013): 1241–56. http://dx.doi.org/10.1007/s10530-013-0545-5.

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Molo, Megan S., James B. White, Vicki Cornish, Richard M. Gell, Oliver Baars, Rakhi Singh, Mary Anna Carbone, et al. "Asymmetrical lineage introgression and recombination in populations of Aspergillus flavus: Implications for biological control." PLOS ONE 17, no. 10 (October 27, 2022): e0276556. http://dx.doi.org/10.1371/journal.pone.0276556.

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Aspergillus flavus is an agriculturally important fungus that causes ear rot of maize and produces aflatoxins, of which B1 is the most carcinogenic naturally-produced compound. In the US, the management of aflatoxins includes the deployment of biological control agents that comprise two nonaflatoxigenic A. flavus strains, either Afla-Guard (member of lineage IB) or AF36 (lineage IC). We used genotyping-by-sequencing to examine the influence of both biocontrol agents on native populations of A. flavus in cornfields in Texas, North Carolina, Arkansas, and Indiana. This study examined up to 27,529 single-nucleotide polymorphisms (SNPs) in a total of 815 A. flavus isolates, and 353 genome-wide haplotypes sampled before biocontrol application, three months after biocontrol application, and up to three years after initial application. Here, we report that the two distinct A. flavus evolutionary lineages IB and IC differ significantly in their frequency distributions across states. We provide evidence of increased unidirectional gene flow from lineage IB into IC, inferred to be due to the applied Afla-Guard biocontrol strain. Genetic exchange and recombination of biocontrol strains with native strains was detected in as little as three months after biocontrol application and up to one and three years later. There was limited inter-lineage migration in the untreated fields. These findings suggest that biocontrol products that include strains from lineage IB offer the greatest potential for sustained reductions in aflatoxin levels over several years. This knowledge has important implications for developing new biocontrol strategies.

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Kochetov, A. V., T. A. Gavrilenko, and O. S. Afanasenko. "New genetic tools for plant defense against parasitic nematodes." Vavilov Journal of Genetics and Breeding 25, no. 3 (June 2, 2021): 337–43. http://dx.doi.org/10.18699/vj21.037.

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Nematodes belong to economically important pests. Here we reviewed the recent data on molecular mechanisms of plant resistance to cyst and gall nematodes including the most devastating Globodera rostochiensis, G. pallida, Heterodera schachtii, Meloidogyne chitwoodi, and M. incognita. The Golden Potato Cyst Nematode (G. rostochiensis, GPCN) may be taken as an example of an economically important pest: in Russia, it occurs in 61 regions with a total area of 1.8 million ha and may cause the yield loss from 19 to 90 %. The biological characteristics of sedentary nematodes makes their agrotechnical control problematic, i.e. the GPCN cysts remain dormant in soil for many years until a susceptible host appears, whereas nematicides are either toxic or inefficient. Introgression of resistance genes (R-genes) from related cultivated or wild species is likely to be the most appropriate way for their biocontrol. The life cycle of sedentary nematodes is based on juveniles’ penetration into the host root where they reprogram plant cells into a syncytium or the so-called ‘giant cells’ and inhibit the plant defense response. Molecular mechanisms of plant-nematode interaction are unusual and this phenomenon provides a very interesting model for the investigation of plant morphogenesis control as well as for the development of new genetic instruments of biocontrol. Here we reviewed recent publications on plant parasitic nematode effectors used for hijacking of the plant immune system, data on R-genes and molecular mechanisms of their activities. In addition, host-induced gene silencing (HIGS) is discussed as a perspective mechanism for nematode biocontrol. HIGS is based on the RNA interference in the cells of the host plant addressed against the nematode genes important for their development and productivity. Several recent investigations demonstrated efficiency of HIGS against sedentary nematodes.

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Sindhu, Satyavir S., Anju Sehrawat, Ruchi Sharma, and Anupma Dahiya. "Biopesticides: Use of Rhizosphere Bacteria for Biological Control of Plant Pathogens." Defence Life Science Journal 1, no. 2 (October 7, 2016): 135. http://dx.doi.org/10.14429/dlsj.1.10747.

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The pesticides used to control pests and diseases are also implicated in ecological, environmental and human health hazards. To reduce the deleterious effects of these agrochemicals, certain antagonistic microorganisms have been characterised from rhizosphere of different crop plants that suppress various plant diseases and thus, minimize the use of pesticides. The application of these specific antagonistic microorganisms in biological control of soilborne pathogens has been studied intensively in the last two decades. These beneficial rhizosphere microorganisms inhibit the pathogenic bacteria and fungi by producing antibiotics, bacteriocins, siderophores, hydrolytic enzymes and other secondary metabolites. The efficiency of these biocontrol products can be improved by manipulation of the environment, using mixtures of beneficial organisms, physiological and genetic enhancement of the biocontrol mechanisms, manipulation of formulations and integration of biocontrol with other alternative methods that provide additive effects. These biocontrol agents could be effectively utilised in sustainable agriculture for improving growth of crop plants.

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Li, Shu, Ping He, Huacai Fan, Lina Liu, Kesuo Yin, Baoming Yang, Yongping Li, Su-Mei Huang, Xundong Li, and Si-Jun Zheng. "A Real-Time Fluorescent Reverse Transcription Quantitative PCR Assay for Rapid Detection of Genetic Markers’ Expression Associated with Fusarium Wilt of Banana Biocontrol Activities in Bacillus." Journal of Fungi 7, no. 5 (April 30, 2021): 353. http://dx.doi.org/10.3390/jof7050353.

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Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), especially Tropical Race 4 (TR4), seriously threatens banana production worldwide. There is no single effective control measure, although certain Bacillus strains secrete antibiotics as promising disease-biocontrol agents. This study identified five Bacillus strains displaying strong antibiotic activity against TR4, using a systemic assessment for presence/absence of genetic markers at genome level, and expression profiles at transcriptome level. A conventional PCR with 13 specific primer pairs detected biocontrol-related genes. An accurate, quantitative real-time PCR protocol with novel designed specific primers was developed to characterise strain-specific gene expression, that optimises strain-culturing and RNA-isolation methodologies. Six genes responsible for synthesising non-ribosomal peptide synthetase biocontrol metabolites were detected in all five strains. Three genes were involved in synthesising three Polyketide synthetase metabolites in all five strains, but the macrolactin synthase gene mln was only detected in WBN06 and YN1282-2. All five Bacillus strains have the genes dhb and bioA, essential for synthesising bacillibactin and biotin. However, the gene sboA, involved in subtilisin synthesis, is absent in all five strains. These genes’ expression patterns were significantly different among these strains, suggesting different mechanisms involved in TR4 biocontrol. Results will help elucidate functional genes’ biocontrol mechanisms.

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Joshi, Raghavendra, and Brian B. McSpadden Gardener. "Identification and Characterization of Novel Genetic Markers Associated with Biological Control Activities in Bacillus subtilis." Phytopathology® 96, no. 2 (February 2006): 145–54. http://dx.doi.org/10.1094/phyto-96-0145.

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Suppressive subtractive hybridization (SSH) was used to identify genetic markers associated with biological control of plant pathogens by Bacillus subtilis. The genomes of two commercialized strains, GB03 and QST713, were compared with that of strain 168, which has no defined biocontrol capacities, to obtain a pool of DNA fragments unique to the two biocontrol strains. The sequences of 149 subtracted fragments were determined and compared with those present in GenBank, but only 80 were found to correspond to known Bacillus genes. Of these, 65 were similar to genes with a wide range of metabolic functions, including the biosynthesis of cell wall components, sporulation, and antibiotic biosynthesis. Sixteen subtracted fragments shared a high degree of similarity to sequences found in multiple B. subtilis strains with proven biocontrol capacities. Oligonucleotide primers specific to nine of these genes were developed. The targeted genes included five genes involved in antibiotic synthesis (bmyB, fenD, ituC,srfAA, and srfAB) and four additional genes (yndJ, yngG, bioA, and a hypothetical open reading frame) not previously associated with biological control. All nine markers were amplified from the commercialized B. subtilis strains GB03, QST713, and MBI600, with the exception of ituC, which was not detected in GB03. The markers also were amplified from four other B. subtilis isolates, but they were not amplified from other related Bacillus strains, including the plant growth-promoting rhizobacteria IN937a and IN937b. Sequencing of the amplified markers revealed that all seven of the isolates that scored positive for multiple markers were genotypically distinct strains. Interestingly, strains scored positive for the amplifiable markers generally were more effective at inhibiting the growth of Rhizoctonia solani and Pythium ultimum than other Bacillus isolates that lacked the markers. The potential utility of the defined genetic markers to further define the diversity, ecology, and biocontrol activities of B. subtilis are discussed.

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Khan, Rahim, Farinazleen Mohamad Ghazali, Nor Ainy Mahyudin, and Nik Iskandar Putra Samsudin. "Biocontrol of Aflatoxins Using Non-Aflatoxigenic Aspergillus flavus: A Literature Review." Journal of Fungi 7, no. 5 (May 12, 2021): 381. http://dx.doi.org/10.3390/jof7050381.

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Aflatoxins (AFs) are mycotoxins, predominantly produced by Aspergillus flavus, A. parasiticus, A. nomius, and A. pseudotamarii. AFs are carcinogenic compounds causing liver cancer in humans and animals. Physical and biological factors significantly affect AF production during the pre-and post-harvest time. Several methodologies have been developed to control AF contamination, yet; they are usually expensive and unfriendly to the environment. Consequently, interest in using biocontrol agents has increased, as they are convenient, advanced, and friendly to the environment. Using non-aflatoxigenic strains of A. flavus (AF−) as biocontrol agents is the most promising method to control AFs’ contamination in cereal crops. AF− strains cannot produce AFs due to the absence of polyketide synthase genes or genetic mutation. AF− strains competitively exclude the AF+ strains in the field, giving an extra advantage to the stored grains. Several microbiological, molecular, and field-based approaches have been used to select a suitable biocontrol agent. The effectiveness of biocontrol agents in controlling AF contamination could reach up to 99.3%. Optimal inoculum rate and a perfect time of application are critical factors influencing the efficacy of biocontrol agents.

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G., Ramangouda, M. K. Naik, Rahul B. Nitnavare, Richa Yeshvekar, Joorie Bhattacharya, Pooja Bhatnagar-Mathur, and Mamta Sharma. "Genetic enhancement of Trichoderma asperellum biocontrol potentials and carbendazim tolerance for chickpea dry root rot disease management." PLOS ONE 18, no. 1 (January 18, 2023): e0280064. http://dx.doi.org/10.1371/journal.pone.0280064.

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Advances in biocontrol potentials and fungicide resistance are highly desirable for Trichoderma. Thus, it is profitable to use mutagenic agents to develop superior strains with enhanced biocontrol properties and fungicide tolerance in Trichoderma. This study investigates the N-methyl-n-nitro-N-nitrosoguanidine (NTG) (100 mg/L) induced mutants of Trichoderma asperellum. Six NTG (3 each from 1st & 2nd round) induced mutants were developed and evaluated their biocontrol activities and carbendazim tolerance. Among the mutant N2-3, N2-1, N1 and N2-2 gave the best antagonistic and volatile metabolite activities on inhibition of chickpea F. oxysporum f. sp. ciceri, B. cinerea and R. bataticola mycelium under in vitro condition. Mutant N2-2 (5626.40 μg/ml) showed the highest EC50 value against carbendazim followed by N2-3 (206.36 μg/ml) and N2-1 (16.41 μg/ml); and succeeded to sporulate even at 2000 μg/ml of carbendazim. The biocontrol activity of N2-2 and N2 with half-dose of carbendazim was evaluated on chickpea dry root rot under controlled environment. Disease reduction and progress of the dry root rot was extremely low in T7 (N2-2 + with half-dose of carbendazim) treatment. Further, carbendazim resistant mutants demonstrated mutation in tub2 gene of β-tubulin family which was suggested through the 37 and 183 residue changes in the superimposed protein structures encoded by tub2 gene in N2 and N2-2 with WT respectively. This study conclusively implies that the enhanced carbendazim tolerance in N2-2 mutant did not affect the mycoparasitism and plant growth activity of Trichoderma. These mutants were as good as the wild-type with respect to all inherent attributes.

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Xiao-Jing, Xu, Zhang Li-Qun, Zhu You-Yong, and Tang Wen-Hua. "Improving biocontrol effect ofPseudomonas fluorescensP5 on plant diseases by genetic modification with chitinase gene." Chinese Journal of Agricultural Biotechnology 2, no. 1 (April 2005): 23–27. http://dx.doi.org/10.1079/cjb200553.

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AbstractPseudomonas fluorescensP5 was isolated in Yunnan Province and proved to be an effective biocontrol agent of various soil-borne plant diseases. The aim of the study was to enhance the biocontrol effect of this strain by introducing a chitinase gene. A 6.5 kb DNA fragment containing the chitinase genechiBwas inserted into pDSK519 vector to construct a new plasmid, pDSK51965. This plasmid was introduced intoP. fluorescensP5 and resulted in a new strain named P5-1. Restriction enzyme digestion and chitin plate culture confirmed that P5-1 contained a functional chitinase gene. Compared with wild-type P5 in pot experiments, P5-1 had an increased effect against rice sheath blight and cotton damping-off caused byRhizoctonia solani. It also increased the effect on suppression of wheat take-all caused byGaeumannomyces graminisvar.tritici.

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Wilkin, J. E., S. F. Shamoun, C. Ritland, K. Ritland, and Y. A. El-Kassaby. "Population genetics of Gaultheria shallon in British Columbia and the implications for management using biocontrol." Canadian Journal of Botany 83, no. 5 (May 1, 2005): 501–9. http://dx.doi.org/10.1139/b05-039.

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Gaultheria shallon Pursh. (salal), an ericaceous shrub native to the Pacific Northwest, often out-competes regenerating conifer species in managed forests. A naturally occurring fungus, Valdensinia heterodoxa Peyronel, is being considered as a potential biocontrol agent for salal. Knowledge of the genetic diversity and population structure of salal will help assess the effectiveness and the potential risks of using a biocontrol agent in natural populations. Salal samples were collected from five populations, four on Vancouver Island and one on coastal mainland British Columbia. DNA fingerprints were obtained based on 230 amplified fragment length polymorphisms (AFLPs), of which 99.1% were variable. While salal has been reported to be a polyploid, it is likely that over time it is moving toward a diploid state. Based on a comparison of allele frequencies with known diploids, the AFLP loci used in this study appear to follow a diploid pattern; however, the levels of variation reported in this study may be an underestimation depending on the ploidy of salal. An intensively sampled population on Vancouver Island (Shawnigan Lake) showed isolation by distance and low kinship correlations, indicative of more sexual reproduction than expected for a predominantly clonal population. Our findings suggest that salal may be clonal at a very local scale (less than 5 m), and that with high levels of diversity within populations and little differentiation among populations, developing an effective biocontrol for salal may be challenging.Key words: population structure, genetic diversity, AFLP, biocontrol, Gaultheria shallon.

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DRAY, F. ALLEN, BRADLEY C. BENNETT, TED D. CENTER, GREG S. WHEELER, and PAUL T. MADEIRA. "Genetic Variation in Melaleuca quinquenervia Affects the Biocontrol Agent Oxyops vitiosa1." Weed Technology 18, sp1 (December 2004): 1400–1402. http://dx.doi.org/10.1614/0890-037x(2004)018[1400:gvimqa]2.0.co;2.

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Ash, Gavin J., Benjamin Stodart, Suchirat Sakuanrungsirikul, Emma Anschaw, Nigel Crump, Deborah Hailstones, and John D. I. Harper. "Genetic characterization of a novelPhomopsissp., a putative biocontrol agent forCarthamus lanatus." Mycologia 102, no. 1 (January 2010): 54–61. http://dx.doi.org/10.3852/08-198.

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Balanza, Virginia, José Enrique Mendoza, Dina Cifuentes, and Pablo Bielza. "Genetic improvement of spinosad resistance in the biocontrol agent Orius laevigatus." BioControl 66, no. 5 (June 2, 2021): 673–85. http://dx.doi.org/10.1007/s10526-021-10093-8.

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Ossanna, Nina, and Sue Mischke. "Genetic Transformation of the Biocontrol Fungus Gliocladium virens to Benomyl Resistance." Applied and Environmental Microbiology 56, no. 10 (1990): 3052–56. http://dx.doi.org/10.1128/aem.56.10.3052-3056.1990.

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Hoddle, Mark S. "Challenges to IPM Advancement: Pesticides, Biocontrol, Genetic Engineering, and Invasive Species." New Zealand Entomologist 29, no. 1 (January 2006): 77–88. http://dx.doi.org/10.1080/00779962.2006.9722141.

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Braman, Charles A., Adam M. Lambert, A. Zeynep Özsoy, Ellen N. Hollstien, Kirsten A. Sheehy, Tara McKinnon, Patrick Moran, John F. Gaskin, John A. Goolsby, and Thomas L. Dudley. "Biology of an Adventive Population of the Armored Scale Rhizaspidiotus donacis, a Biological Control Agent of Arundo donax in California." Insects 12, no. 7 (June 29, 2021): 588. http://dx.doi.org/10.3390/insects12070588.

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Arundo donax (giant reed) is invasive in Mediterranean, sub-, and tropical riparian systems worldwide. The armored scale Rhizaspidiotus donacis is approved for biocontrol in North America, but an adventive population was recently discovered in southern California. We documented this population’s distribution, phylogeny, phenology, potential host spillover to Phragmites spp., and potential for parasitism by a common biocontrol parasitoid of citrus scale. The adventive scale was found within a single watershed and is genetically closest to Iberian scale genotypes. Rhizaspidiotus donacis developed on Phragmites haplotypes but at much lower densities than Arundo. The adventive population is univoltine, producing crawlers from March-June. Aphytis melinus parasitoids exhibited sustained interest in R. donacis during choice and no-choice trials and oviposition resulted in a small second generation. Rhizaspidiotus donacis appears limited in distribution by its univoltinism and sessile adult females. This presents challenges for broad biocontrol implementation but allows for targeted application. The genetic differentiation between imported biocontrol samples and adventive populations presents an opportunity for exploring benefits of hybrids and/or alternative genotypes where establishment has been difficult. While unlikely to occur in situ, spillover to vulnerable endemic Phragmites or deleterious parasitoid effects on scale biocontrol agents warrants consideration when planning use of R. donacis.

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Becker, Elisa M., L. Alex Ball, Michael T. Dumas, Doug G. Pitt, Ronald E. Wall, and William E. Hintz. "Chondrostereum purpureum as a biological control agent in forest vegetation management. III. Infection survey of a national field trial." Canadian Journal of Forest Research 29, no. 7 (August 1, 1999): 859–65. http://dx.doi.org/10.1139/x99-137.

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A nationally coordinated field trial was established in the summer of 1995 to assess the utility of Chondrostereum purpureum (Pers. ex Fr.) Pouzar as a biocontrol agent for several weedy deciduous species. In this study, C. purpureum infection of cut stumps was surveyed 4 months following applications of the biocontrol agent in New Brunswick and Ontario field trials. The use of diagnostic molecular genetic markers to detect and identify C. purpureum was compared with morphological identification methods. Samples of trembling aspen (Populus tremuloides Michx.) and red maple (Acer rubrum L.) from the New Brunswick trials confirmed infection with the biocontrol isolates of C. purpureum, and no cross contamination of treatment applications was detected. Analyses of recovered fungal samples from aspen and speckled alder (Alnus rugosa (Du Roi) Spreng.) in Ontario also confirmed the success of biocontrol infection. The percentage of C. purpureum infected stumps differed between hosts in the Ontario trials. An average of 84% of speckled alder stems and 54% of aspen stems were estimated to have been infected by the applied isolates of C. purpureum. Given a sufficient number of samples, this methodology can provide an early indication of successful stump infection by C. purpureum, a prerequisite for effective weed biocontrol.

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Ashraf, Hafiza Javaria, Komivi Senyo Akutse, Irum Mukhtar, Luis Carlos Ramos Aguila, Muhammad Qasim, Wenjie Wang, Bamisope Steve Bamisile, and Liande Wang. "Genetic Diversity of Tamarixia radiata Populations and Their Associated Endosymbiont Wolbachia Species from China." Agronomy 11, no. 10 (October 8, 2021): 2018. http://dx.doi.org/10.3390/agronomy11102018.

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Tamarixia radiata is one of the established biocontrol pests against the major Asian citrus psyllid, Diaphorina citri, a vector of Candidatus Liberibacter that is a causal agent of citrus Huanglongbing (HLB) disease. Updated information and regional exploration on biocontrol pests are important elements for effective disease management strategies. In this study, the diversity and parasitism rate of T. radiata populations were evaluated. Due to the importance of the host–parasitoid relationship, the presence of Wolbachia as an endosymbiont was also investigated. The parasitism rate of various T. radiata populations from Ecuador and China ranged between 57.27% and 66.32%, respectively, with a non-significant emergence rate and a statistically similar sex ratio. Sequence analysis of ITS and COI from T. radiata populations was consistent with the morphological hypothesis that the collections represent a single species, whereas phylogeny of the wsp gene confirmed the presence of Wolbachia pipientis as an endosymbiont within T. radiata populations. Based on partial COI sequences, the maximum genetic diversity such as total haplotype diversity (Hd = 0.788), nucleotide, diversity (π = 0.2439), and average nucleotide difference (k = 171.844) was also estimated for different T. radiata populations. Furthermore, neutrality tests based on COI sequences indicated an overall contraction in T. radiata populations, whereas an expansion trend was observed in associated W. pipientis strains. This study clearly demonstrated the presence of genetically diverse T. radiata populations that were able to parasitize D. citri effectively, and these can be further explored as promising biocontrol candidates in integrated pest management strategies to solve citriculture economic loss caused by D. citri.

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Chinchilla-Ramírez, Milena, Meritxell Pérez-Hedo, Bart A. Pannebakker, and Alberto Urbaneja. "Genetic Variation in the Feeding Behavior of Isofemale Lines of Nesidiocoris tenuis." Insects 11, no. 8 (August 7, 2020): 513. http://dx.doi.org/10.3390/insects11080513.

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Zoophytophagous predators provide biocontrol services in various major crops of modern horticulture due to the combination of its predatory capacity and the induction of plant defenses derived from its phytophagy. However, under certain conditions of prey scarcity, these natural enemies can inflict plant damage. Exploitation of genetic variation and subsequent selective breeding on foraging traits is a potential alternative to overcome this inconvenience. In this study, we quantified the genetic variation of phytophagy and zoophagy of Nesidiocoristenuis (Reuter) (Hemiptera: Miridae), a zoophytophagous predator widely used in tomato crops to suppress key pests. We compared nine isofemale lines on their capacity to produce necrotic rings and wilting on tomato plants as a proxy for phytophagy, as well as their efficacy to prey on Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, as a proxy for zoophagy. Differences between isofemale lines in phytophagy and zoophagy indicated a genetic basis. Variation found in the zoophagy levels was larger than that in phytophagy levels. Our results showed that there is a genetic basis for the variation observed in the feeding behavior of isofemale lines of N.tenuis, highlighting the potential importance of selective breeding for such traits of biocontrol interest.

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Wang, Niuniu, Yongjie Zhang, Xianzhi Jiang, Chi Shu, M. Imran Hamid, Muzammil Hussain, Senyu Chen, Jianping Xu, Meichun Xiang, and Xingzhong Liu. "Population Genetics of Hirsutella rhossiliensis, a Dominant Parasite of Cyst Nematode Juveniles on a Continental Scale." Applied and Environmental Microbiology 82, no. 21 (August 19, 2016): 6317–25. http://dx.doi.org/10.1128/aem.01708-16.

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ABSTRACTHirsutella rhossiliensisis a parasite of juvenile nematodes, effective against a diversity of plant-parasitic nematodes. Its global distribution on various nematode hosts and its genetic variation for several geographic regions have been reported, while the global population genetic structure and factors underlying patterns of genetic variation ofH. rhossiliensisare unclear. In this study, 87H. rhossiliensisstrains from five nematode species (Globoderasp.,Criconemella xenoplax,Rotylenchus robustus,Heterodera schachtii, andHeterodera glycines) in Europe, the United States, and China were investigated by multilocus sequence analyses. A total of 280 variable sites (frequency, 0.6%) at eight loci and six clustering in high accordance with geographic populations or host nematode-associated populations were identified. AlthoughH. rhossiliensisis currently recognized as an asexual fungus, recombination events were frequently detected. In addition, significant genetic isolation by geography and nematode hosts was revealed. Overall, our analyses showed that recombination, geographic isolation, and nematode host adaptation have played significant roles in the evolutionary history ofH. rhossiliensis.IMPORTANCEH. rhossiliensishas great potential for use as a biocontrol agent to control nematodes in a sustainable manner as an endoparasitic fungus. Therefore, this study has important implications for the use ofH. rhossiliensisas a biocontrol agent and provides interesting insights into the biology of this species.

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Kang, Ji Hyoun, Changseob Lim, Sung Hwan Park, Wang Gyu Kim, Nattawut Sareein, and Yeon Jae Bae. "Genetic and Morphologic Variation in a Potential Mosquito Biocontrol Agent, Hydrochara Affinis (Coleoptera: Hydrophilidae)." Sustainability 12, no. 13 (July 7, 2020): 5481. http://dx.doi.org/10.3390/su12135481.

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Hydrochara affinis (Coleoptera: Hydrophilidae), a water scavenger beetle, was recently identified as a natural and effective agent for biological mosquito control; it was reported to exhibit high rates of mosquito larvae predation. However, maintaining the quality (i.e., natural ecological attributes, such as genetic variation) of laboratory-reared populations is essential for ensuring the long-term success of biological control programs. Accordingly, here, we aimed to use mitochondrial Cytochrome c oxidase subunit I (COI) sequences to document the genetic diversity, population structure, and phylogenetic position of natural and lab-reared H. affinis populations in South Korea and use geometric morphometric analysis to investigate the populations’ morphological divergence. The natural H. affinis populations possessed high genetic diversity and numerous COI haplotypes, suggesting that these populations were healthy and could be directly applied to mosquito habitats without alterations to their natural genetic attributes. The lab-reared populations also possessed high genetic diversity and, thus, the potential for high adaptive capacity to new environments. Although no distinct population genetic structures were observed, quantitative variation was observed in the body shape of both the natural and lab-reared populations. The high levels of genetic and morphologic variation observed in the H. affinis populations examined here indicate the species’ favorable conservation status, genetic diversity, adaptive capacity, and, thus, “suitability” for field application as an effective mosquito control agent.

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Pennerman, Kayla K., Guohua Yin, Joan W. Bennett, and Sui-Sheng T. Hua. "Aspergillus flavus NRRL 35739, a Poor Biocontrol Agent, May Have Increased Relative Expression of Stress Response Genes." Journal of Fungi 5, no. 2 (June 20, 2019): 53. http://dx.doi.org/10.3390/jof5020053.

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Biocontrol of the mycotoxin aflatoxin utilizes non-aflatoxigenic strains of Aspergillus flavus, which have variable success rates as biocontrol agents. One non-aflatoxigenic strain, NRRL 35739, is a notably poor biocontrol agent. Its growth in artificial cultures and on peanut kernels was found to be slower than that of two aflatoxigenic strains, and NRRL 35739 exhibited less sporulation when grown on peanuts. The non-aflatoxigenic strain did not greatly prevent aflatoxin accumulation. Comparison of the transcriptomes of aflatoxigenic and non-aflatoxigenic A. flavus strains AF36, AF70, NRRL 3357, NRRL 35739, and WRRL 1519 indicated that strain NRRL 35739 had increased relative expression of six heat shock and stress response proteins, with the genes having relative read counts in NRRL 35739 that were 25 to 410 times more than in the other four strains. These preliminary findings tracked with current thought that aflatoxin biocontrol efficacy is related to the ability of a non-aflatoxigenic strain to out-compete aflatoxigenic ones. The slower growth of NRRL 35739 might be due to lower stress tolerance or overexpression of stress response(s). Further study of NRRL 35739 is needed to refine our understanding of the genetic basis of competitiveness among A. flavus strains.

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Pinski, Artur, Joanna Zur, Robert Hasterok, and Katarzyna Hupert-Kocurek. "Comparative Genomics of Stenotrophomonas maltophilia and Stenotrophomonas rhizophila Revealed Characteristic Features of Both Species." International Journal of Molecular Sciences 21, no. 14 (July 12, 2020): 4922. http://dx.doi.org/10.3390/ijms21144922.

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Although Stenotrophomonas maltophilia strains are efficient biocontrol agents, their field applications have raised concerns due to their possible threat to human health. The non-pathogenic Stenotrophomonas rhizophila species, which is closely related to S. maltophilia, has been proposed as an alternative. However, knowledge regarding the genetics of S. rhizophila is limited. Thus, the aim of the study was to define any genetic differences between the species and to characterise their ability to promote the growth of plant hosts as well as to enhance phytoremediation efficiency. We compared 37 strains that belong to both species using the tools of comparative genomics and identified 96 genetic features that are unique to S. maltophilia (e.g., chitin-binding protein, mechanosensitive channels of small conductance and KGG repeat-containing stress-induced protein) and 59 that are unique to S. rhizophila (e.g., glucosylglycerol-phosphate synthase, cold shock protein with the DUF1294 domain, and pteridine-dependent dioxygenase-like protein). The strains from both species have a high potential for biocontrol, which is mainly related to the production of keratinases (KerSMD and KerSMF), proteinases and chitinases. Plant growth promotion traits are attributed to the biosynthesis of siderophores, spermidine, osmoprotectants such as trehalose and glucosylglycerol, which is unique to S. rhizophila. In eight out of 37 analysed strains, the genes that are required to degrade protocatechuate were present. While our results show genetic differences between the two species, they had a similar growth promotion potential. Considering the information above, S. rhizophila constitutes a promising alternative for S. maltophilia for use in agricultural biotechnology.

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Pasini, Luca, Daniele Prodorutti, Sandro Pastorelli, and Ilaria Pertot. "Genetic Diversity and Biocontrol of Rosellinia necatrix Infecting Apple in Northern Italy." Plant Disease 100, no. 2 (February 2016): 444–52. http://dx.doi.org/10.1094/pdis-04-15-0480-re.

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The soilborne fungus Rosellinia necatrix is the causal agent of white root rot disease on numerous plant species, including apple, which, together with the ability to survive in soil for long periods, makes this pathogen difficult to control. To understand the origins of pathogen infestation, a survey of diseased apple orchards in the northeast of Italy was conducted and 35 isolates of R. necatrix were characterized with intersimple sequence repeat markers. High genetic heterogeneity among the collected isolates suggested multiple preexisting sources of inoculum and not movement of infected soil or plant material from a single source. Greenhouse trials confirmed that, as with some other crops, soil water content and temperature were the main factors influencing infection of apple plants, while organic fertilizers and the incorporation of apple wood residues were less important. The efficacy of Trichoderma atroviride SC1 as a biocontrol agent against R. necatrix greatly depended on the timing of application. It reduced white root rot incidence on apple seedlings only if treatment was applied at least 1 week before planting.

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Mayonde, S., G. V. Cron, K. L. Glennon, and M. J. Byrne. "Genetic diversity assessment of Tamarix in South Africa – Biocontrol and conservation implications." South African Journal of Botany 121 (March 2019): 54–62. http://dx.doi.org/10.1016/j.sajb.2018.10.030.

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Glick, Bernard R., and Yoav Bashan. "Genetic manipulation of plant growth-promoting bacteria to enhance biocontrol of phytopathogens." Biotechnology Advances 15, no. 2 (January 1997): 353–78. http://dx.doi.org/10.1016/s0734-9750(97)00004-9.

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Schena, Leonardo, Antonio Ippolito, Tirtza Zahavi, Lea Cohen, Franco Nigro, and Samir Droby. "Genetic diversity and biocontrol activity of Aureobasidium pullulans isolates against postharvest rots." Postharvest Biology and Technology 17, no. 3 (November 1999): 189–99. http://dx.doi.org/10.1016/s0925-5214(99)00036-8.

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Francis, J. R. "Biocontrol potential and genetic diversity of Metarhizium anisopliae lineage in agricultural habitats." Journal of Applied Microbiology 127, no. 2 (July 2019): 556–64. http://dx.doi.org/10.1111/jam.14328.

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Porteous-Álvarez, Alejandra J., Sara Mayo-Prieto, Samuel Álvarez-García, Bonifacio Reinoso, and Pedro A. Casquero. "Genetic Response of Common Bean to the Inoculation with Indigenous Fusarium Isolates." Journal of Fungi 6, no. 4 (October 16, 2020): 228. http://dx.doi.org/10.3390/jof6040228.

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Fungal species from the genus Fusarium are important soil-borne pathogens worldwide, causing significant economic losses in diverse crops. The need to find sustainable solutions against this disease has led to the development of new strategies—for instance, the use of biocontrol agents. In this regard, non-pathogenic Fusarium isolates have demonstrated their ability to help other plants withstand subsequent pathogen attacks. In the present work, several Fusarium isolates were evaluated in climatic chambers to identify those presenting low or non-pathogenic behavior. The inoculation with a low-pathogenic isolate of the fungus did not affect the development of the plant, contrary to the results observed in plants inoculated with pathogenic isolates. The expression of defense-related genes was evaluated and compared between plants inoculated with pathogenic and low-pathogenic Fusarium isolates. Low-pathogenic isolates caused a general downregulation of several plant defense-related genes, while pathogenic ones produced an upregulation of these genes. This kind of response to low-pathogenic fungal isolates has been already described for other plant species and fungal pathogens, being related to enhanced tolerance to later pathogen attacks. The results here presented suggest that low-pathogenic F. oxysporum and F. solani isolates may have potential biocontrol activity against bean pathogens via induced and systemic responses in the plant.

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van den Broek, Daan, Thomas F. C. Chin-A-Woeng, Kevin Eijkemans, Ine H. M. Mulders, Guido V. Bloemberg, and Ben J. J. Lugtenberg. "Biocontrol Traits of Pseudomonas spp. Are Regulated by Phase Variation." Molecular Plant-Microbe Interactions® 16, no. 11 (November 2003): 1003–12. http://dx.doi.org/10.1094/mpmi.2003.16.11.1003.

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Of 214 Pseudomonas strains isolated from maize rhizosphere, 46 turned out to be antagonistic, of which 43 displayed clear colony phase variation. The latter strains formed both opaque and translucent colonies, designated as phase I and phase II, respectively. It appeared that important biocontrol traits, such as motility and the production of antifungal metabolites, proteases, lipases, chitinases, and biosurfactants, are correlated with phase I morphology and are absent in bacteria with phase II morphology. From a Tn5luxAB transposon library of Pseudomonas sp. strain PCL1171 phase I cells, two mutants exhibiting stable expression of phase II had insertions in gacS. A third mutant, which showed an increased colony phase variation frequency was mutated in mutS. Inoculation of wheat seeds with PCL1171 bacteria of phase I morphology resulted in efficient suppression of take-all disease, whereas disease suppression was absent with phase II bacteria. Neither the gacS nor the mutS mutant was able to suppress take-all, but biocontrol activity was restored after genetic complementation of these mutants. Furthermore, in a number of cases, complementation by gacS of wild-type phase II sectors to phase I phenotype could be shown. A PCL1171 phase I mutant defective in antagonistic activity appeared to have a mutation in a gene encoding a lipopeptide synthetase homologue and had lost its biocontrol activity, suggesting that biocontrol by strain PCL1171 is dependent on the production of a lipopeptide. Our results show that colony phase variation plays a regulatory role in biocontrol by Pseudomonas bacteria by influencing the expression of major biocontrol traits and that the gacS and mutS genes play a role in the colony phase variation process. Therefore phase variation not only plays a role in escaping animal defense but it also appears to play a much broader and vital role in the ecology of bacteria producing exoenzymes, antibiotics, and other secondary metabolites.

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Sun, Yan, Carine Beuchat, and Heinz Müller-Schärer. "Is biocontrol efficacy rather driven by the plant or the antagonist genotypes? A conceptual bioassay approach." NeoBiota 63 (December 8, 2020): 81–100. http://dx.doi.org/10.3897/neobiota.63.54962.

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In the new range, invasive species lack their specialist co-evolved natural enemies, which then might be used as biocontrol agents. Populations of both a plant invader in the introduced range and its potential biocontrol agents in the native range may be genetically differentiated among geographically distinct regions. This, in turn, is expected to affect the outcome of their interaction when brought together, and by this the efficacy of the control. It further raises the question, is the outcome of such interactions mainly driven by the genotype of the plant invader (some plant genotypes being more resistant/tolerant to most of the antagonist genotypes), or by the antagonist genotype (some antagonist genotypes being more effective against most of the plant genotypes)? This is important for biocontrol management, as only the latter is expected to result in more effective control, when introducing the right biocontrol agent genotypes. In a third scenario, where the outcome of the interaction is driven by a specific plant by antagonist genotype interactions, an effective control will need the introduction of carefully selected multiple antagonist genotypes. Here, we challenged in a complete factorial design 11 plant genotypes (mainly half-siblings) of the invasive Ambrosia artemisiifolia with larvae of eight genotypes (full-siblings) of the leaf beetle Ophraella communa, a potential biocontrol insect, and assessed larval and adult performance and leaf consumption as proxies of their expected impact on the efficacy of biological control. Both species were collected from several locations from their native (USA) and introduced ranges (Europe and China). In summary, we found O. communa genotype to be the main driver of this interaction, indicating the potential for at least short-term control efficacy when introducing the best beetle genotypes. Besides the importance of investigating the genetic structure both among and within populations of the plant invader and the biocontrol agent during the pre-release phase of a biocontrol program, we advocate integrating such bioassays, as this will give a first indication of the probability for an – at least – short- to mid-term efficacy when introducing a potential biocontrol agent, and on where to find the most efficient agent genotypes.

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Kitaev, Konstantin A., Maksim B. Udalov, and Galina V. Benkovskaya. "Molecular-genetic methods of the investigation of trophic relations hips in the agrocoenosis." Ecological genetics 9, no. 4 (December 15, 2011): 15–24. http://dx.doi.org/10.17816/ecogen9415-24.

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The problem of determine quantitative predation rate is actuality for development methods of biocontrol. Many species of insect could not be investigated by traditional methods through features of its behavior and life-form, and we have must analyzed gut content of predators. Efficacy and cost of two methods analyzes (PCR and antibodies) are compared. Project of experiment with PCR -analyze is described and additional possibility of PCR -analyze is shown.

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Diabankana, Roderic Gilles Claret, Elena Urievna Shulga, Shamil Zavdatovich Validov, and Daniel Mawuena Afordoanyi. "Genetic Characteristics and Enzymatic Activities of Bacillus velezensis KS04AU as a Stable Biocontrol Agent against Phytopathogens." International Journal of Plant Biology 13, no. 3 (July 18, 2022): 201–22. http://dx.doi.org/10.3390/ijpb13030018.

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Bacillus velezensis has a broad application in the agricultural and industrial sectors for its biocontrol properties and its potential active secondary metabolites. The defined phenotypic characteristics of a strain vary according to its ecosystem. We report the complete genomic analysis of B. velezensis KS04AU compared to four strains of B. velezensis (SRCM102752, ONU-553, FZB42, and JS25R) and two closely related Bacillus amyloliquefaciens (LL3 and IT-45). A total of 4771 protein coding genes comprises the KS04AU genome, in comparison with 3334 genes core genes found in the six other strains and the remaining 1437 shell genes. Average nucleotide identity of the target strain to the six other strains showed 99.65% to B. velezensis ONU-553, sharing 60 orthologous genes. Secondary metabolite gene cluster analysis of all strains showed that KS04AU has a mersacidin cluster gene, which is absent in the genome of the other strains. PHASTER analysis also showed KS04AU harboring two phages (Aeribacllus AP45 NC_048651 and Paenibacillus_Tripp NC_028930), which were also unique in comparison with the other strains. Analysis on anti-microbial resistance genes showed no difference in the genome of KS04AU to any of the other genomes, with the exception of B. amyloliquefaciens IT-45 which had one unique small multidrug-resistance antibiotic efflux-pump gene (qacJ). The CRISPR-Cas systems in the strains were also compared showing one CRISPR gene found only in KS04AU. Hydrolytic activity, antagonistic activity against phytopathogens (Fusarium oxysporum, Fusarium graminearum, Alternaria alternata and Pseudomonas syringae) and biocontrol against tomato foot and root rot experiments were carried out. B. velezensis KS04AU inhibits the growth of all phytopathogens tested, produces hydrolytic activity, and reduces Fusarium oxysporum f.sp. radicis-lycopersici (Forl) ZUM2407 lesions up to 46.02 ± 0.12%. The obtained results confirm B. velezensis KS04AU as a potential biocontrol strain for plant protection.

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Gunasekera, T. S., R. J. Holland, M. R. Gillings, D. A. Briscoe, D. C. Neethling, K. L. Williams, and K. MH Nevalainen. "Phenotypic and genetic characterization of Paecilomyces lilacinus strains with biocontrol activity against root-knot nematodes." Canadian Journal of Microbiology 46, no. 9 (September 1, 2000): 775–83. http://dx.doi.org/10.1139/w00-062.

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Efficient selection of fungi for biological control of nematodes requires a series of screening assays. Assessment of genetic diversity in the candidate species maximizes the variety of the isolates tested and permits the assignment of a particular genotype with high nematophagous potential using a rapid novel assay. Molecular analyses also facilitate separation between isolates, allowing the identification of proprietary strains and trace biocontrol strains in the environment. The resistance of propagules to UV radiation is an important factor in the survival of a biocontrol agent. We have analyzed 15 strains of the nematophagous fungus Paecilomyces lilacinus using these principles. Arbitrarily primed DNA and allozyme assays were applied to place the isolates into genetic clusters, and demonstrated that some genetically related P. lilacinus strains exhibit widespread geographic distributions. When exposed to UV radiation, some weakly nematophagous strains were generally more susceptible than effective isolates. A microtitre tray-based assay used to screen the pathogenic activity of each isolate to Meloidogyne javanica egg masses revealed that the nematophagous ability varied between 37%-100%. However, there was no clear relationship between nematophagous ability and genetic clusters. Molecular characterizations revealed sufficient diversity to allow tracking of strains released into the environment.Key words: Paecilomyces lilacinus, LP-RAPD analysis, allozymes, UV sensitivity.

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48

Samson, Robert A. "Constraints associated with taxonomy of biocontrol fungi." Canadian Journal of Botany 73, S1 (December 31, 1995): 83–88. http://dx.doi.org/10.1139/b95-229.

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An increasing number of fungi are being collected and screened for the biological control of pests, but nomenclature, taxonomy, and correct identification of many of them remain problematic. Trichoderma spp. and the rust fungi are promising candidates for biocontrol agents, yet they present serious taxonomic problems. Several groups of entomopathogenic fungi are also potential biocontrol sources of agents. Genera such as Cordyceps, Aschersonia, Verticillium, Beauveria, and Metarhizium are in need of urgent revision. Before their release can be considered, all details of their complex life cycles and taxonomy have to be elucidated to satisfy quarantine authorities. Formerly, the taxonomy and identification of biocontrol fungi has been based largely on morphological structures, but molecular techniques have been introduced to provide more objective criteria. Beauveria and Metarhizium spp. have been subjected to several molecular techniques that have resolved phylogeny and species concepts. In Metarhizium, a high degree of genetic diversity is present. Incorrect typification, lack of holotypes, and poorly resolved life cycles and unclear teleomorph – (syn)anamorph connections are serious taxonomic contraints. Only a small fraction of the fungi that can be used for biological control has been examined. The destruction of habitats and ecosystems for these fungi will result in the disappearance of fungal germ plasm of potential value, not only for biological control but also as a source of novel metabolites. This loss and the decline of taxonomic expertise in the fungi are major problems. Key words: biocontrol, taxonomy, Trichoderma, Beauveria, Metarhizium, Cordyceps.

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Kagot, Victor, Sheila Okoth, Marthe De Boevre, and Sarah De Saeger. "Biocontrol of Aspergillus and Fusarium Mycotoxins in Africa: Benefits and Limitations." Toxins 11, no. 2 (February 13, 2019): 109. http://dx.doi.org/10.3390/toxins11020109.

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Fungal contamination and the consequent mycotoxin production is a hindrance to food and feed safety, international trade and human and animal health. In Africa, fungal contamination by Fusarium and Aspergillus is heightened by tropical climatic conditions that create a suitable environment for pre- and postharvest mycotoxin production. The biocontrol of Fusarium and its associated fusariotoxins has stagnated at laboratory and experimental levels with species of Trichoderma, Bacillus and atoxigenic Fusarium being tested as the most promising candidates. Hitherto, there is no impetus to upscale for field use owing to the inconsistent results of these agents. Non-aflatoxigenic strains of Aspergillus have been developed to create biocontrol formulations by outcompeting the aflatoxigenic strains, thus thwarting aflatoxins on the target produce by 70% to 90%. Questions have been raised on their ability to produce other mycotoxins like cyclopiazonic acid, to potentially exchange genetic material and to become aflatoxigenic with consequent deleterious effects on other organisms and environments. Other biocontrol approaches to mitigate aflatoxins include the use of lactic acid bacteria and yeast species which have demonstrated the ability to prevent the growth of Aspergillus flavus and consequent toxin production under laboratory conditions. Nevertheless, these strategies seem to be ineffective under field conditions. The efficacy of biological agents is normally dependent on environmental factors, formulations’ safety to non-target hosts and the ecological impact. Biocontrol agents can only be effectively evaluated after long-term use, causing a never-ending debate on the use of live organisms as a remedy to pests and diseases over the use of chemicals. Biocontrol should be used in conjunction with good agricultural practices coupled with good postharvest management to significantly reduce mycotoxins in the African continent.

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EI-Kawokgy,, Tahany, M. Zowail, Wafaa Hegazy, and Halima Salem. "GENETIC IMPROVEMENT OF Bacillus thuringiensis AS A BIOCONTROL AGENT AGAINST BiomphaJaria aJexandrina SNAIL." Journal of Plant Protection and Pathology 29, no. 9 (September 1, 2004): 5317–34. http://dx.doi.org/10.21608/jppp.2004.240014.

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Journal articles on the topic 'Genetic biocontrol'

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