▪ Abstract Losses from postharvest fruit diseases range from 1 to 20 percent in the United States, depending on the commodity. The application of fungicides to fruits after harvest to reduce decay has been increasingly curtailed by the development of pathogen resistance to many key fungicides, the lack of replacement fungicides, negative public perception regarding the safety of pesticides and consequent restrictions on fungicide use. Biological control of postharvest diseases (BCPD) has emerged as an effective alternative. Because wound-invading necrotrophic pathogens are vulnerable to biocontrol, antagonists can be applied directly to the targeted area (fruit wounds), and a single application using existing delivery systems (drenches, line sprayers, on-line dips) can significantly reduce fruit decays. The pioneering biocontrol products BioSave and Aspire were registered by EPA in 1995 for control of postharvest rots of pome and citrus fruit, respectively, and are commercially available. The limitations ...

Biological control of postharvest diseases of fruits.

https://krishi.icar.gov.in/jspui/bitstream/123456789/28711/1/Dr.%20Rajbir%20Singh_Biological%20Control.pdf

Biological control of postharvest diseases of fruits and vegetables by microbial antagonists: A review

Although the number of biocontrol products is increasing, these products still represent only about 1% of agricultural chemical sales. Yet these are important contributions because biocontrol agents offer disease management alternatives with different mechanisms of action than chemical pesticides. Trends in research include the increased use of biorational screening processes to identify microorganisms with potential for biocontrol, increased testing under semicommercial and commercial production conditions, increased emphasis on combining biocontrol strains with each other and with other control methods, integrating biocontrol into an overall system.

Commercialization and Implementation of Biocontrol 1

https://pubag.nal.usda.gov/pubag/downloadPDF.xhtml?id=28805&content=PDF

Twenty years of postharvest biocontrol research: Is it time for a new paradigm?

s Background Impressive progress was made in the last decade in development, registration and commercialization of biocontrol products based on yeast to manage postharvest pathogens of fruit. To successfully inhibit the pathogen infection and development, several possible mechanisms operate in a tritrophic host-pathogen-antagonist interaction system. Scope and Approach The current reviews focuses on the recent knowledge on the mechanisms by which yeast biocontrol agents (BCAs) interact with pathogens and fruit tissues. The main mechanisms of action explored include antibiosis, mycoparasitism, production of lytic enzymes, induced resistance, competition for limiting nutrients and space, and the role of oxidative stress. Omics techniques can provide a powerful tool to study complex fruit host-pathogen-antagonist-native microflora interactions. Key Findings and Conclusions Various aspects relevant to mechanisms of action of yeast antagonists have been discussed, including unique environment of surface wounds, iron competition, biofilm formation, cell wall degrading enzymes, and involvement of oxidative stress. Outstanding advancement in molecular and omics technologies revolutionized the research about the physiological status of BCAs and the global effect of the application of BCAs on the transcriptome and/or proteome of fruit. Microbial communities on plant surfaces could impact disease control through their interactions with host plants, pathogens, and BCAs, in a quadritrophic interaction system, hence microbiome research opens new research opportunities. The complex modes of action make antagonistic performance and efficacy more dependent on production, formulation, packing, application, and storage. A deep understanding of the mode of action is essential to develop appropriate formulation and methods of application.

Development of biocontrol products for postharvest diseases of fruit: The importance of elucidating the mechanisms of action of yeast antagonists

Castoria, R., Caputo, L., De Curtis, F., and De Cicco, V. 2003. Resistance of postharvest biocontrol yeasts to oxidative stress: A possible new mechanism of action. Phytopathology 93:564-572. We detected the generation of the reactive oxygen species (ROS) superoxide anion ( 2 O ) and hydrogen peroxide (H2O2) in apple wounds immediately after wounding, and assessed the relationships between (i) timely colonization of apple wounds by biocontrol yeasts, (ii) resistance of these microorganisms to oxidative stress caused by ROS, and (iii) their antagonism against postharvest wound pathogens. We analyzed a model system consisting of two yeasts with higher (Cryptococcus laurentii LS28) or lower (Rhodotorula glutinis LS-11) antagonistic activity against the postharvest pathogens Botrytis cinerea and Penicillium expansum. LS-28 exhibited faster and greater colonization of wounds than LS-11. In contrast to LS-28, the number of LS-11 cells dropped 1 and 2 h after application, and then increased only later. In vitro, LS-28 was more resistant to ROS-generated oxidative stress. The combined application of biocontrol yeasts and ROS-deactivating enzymes in apple wounds prevented the decrease in number of LS-11 cells mentioned above, and enhanced colonization and antagonistic activity of both biocontrol yeasts against B. cinerea and P. expansum. Polar lipids of LS-11 contained the more unsaturated and oxidizable -linolenic acid, which was absent in LS-28. Resistance to oxidative stress could be a key mechanism of biocontrol yeasts antagonism against postharvest wound pathogens. Additional keyword: Malus domestica.

https://apsjournals.apsnet.org/doi/pdfplus/10.1094/PHYTO.2003.93.5.564

Resistance of postharvest biocontrol yeasts to oxidative stress: a possible new mechanism of action.

β-1,3-glucanase activity of two saprophytic yeasts and possible mode of action as biocontrol agents against postharvest diseases

More than 200 yeasts were selectively isolated from microbial populations on the surface of different fruits. Fifty of these isolates were tested against blue mould ( Penicillium expansum ) on wounded apples. Isolates LS-11 of Rhodotorula glutinis and LS-28 of Cryptococcus laurentii were the most effective antagonists. They were further evaluated at 20IC on different fruits (apples, pears, strawberries, kiwi fruits and table grapes) against several of the main post-harvest pathogens ( Botrytis cinerea, Penicillium expansum, Rhizopus stolonifer and Aspergillus niger ) and at 4IC on apples inoculated with P. expansum . At 20IC the antagonists significantly reduced rot incidence and showed a wide range of activity on different hostpathogen combinations; isolate LS-28 exhibited a higher and more stable activity than LS-11. Both yeasts were also effective against P. expansum in cold storage conditions. Populations of the two yeasts were assessed on wounded and unwounded surfaces of apples kept at both 20 and 4...

Activity of the Yeasts Cryptococcus laurentii and Rhodotorula glutinis Against Post-harvest Rots on Different Fruits

Contamination of apples (Malus domestica) and derived juices with fungicide residues and patulin produced by Penicillium expansum are major issues of food safety. Biocontrol agents represent an alternative or supplement to chemicals for disease control. Our data show that these microbes could also contribute to actively decreasing patulin accumulation in apples. Three biocontrol agents, Rhodotorula glutinis LS11, Cryptococcus laurentii LS28, and Aureobasidium pullulans LS30, were examined for their in vitro growth in the presence of patulin and for their capability to decrease mycotoxin recovery from the medium. Strain LS11 yielded the highest growth rates and the greatest decrease of toxin recoveries. Further, it caused the appearance of two major spots on thin-layer chromatography (TLC) plates, suggesting possible metabolization of the mycotoxin. In vivo, i.e., in the low percentage of LS11-pretreated apples infected by P. expansum, patulin accumulation was significantly lower than in nontreated infected fruits. Yeast cells survived and increased in infected apples and, in a model system emulating decaying apple, resulted in accelerated breakdown of patulin and the production of the same TLC spots as those detected in vitro. These data suggest that biocontrol yeast cells surviving in decaying apples could metabolize patulin and/or negatively affect its accumulation or synthesis. To our knowledge, this is the first report describing the effect of a biocontrol agent on patulin accumulation in vivo.

https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-95-1271

Filippo De Curtis

Papers

Resistance of postharvest biocontrol yeasts to oxidative stress: a possible new mechanism of action.

β-1,3-glucanase activity of two saprophytic yeasts and possible mode of action as biocontrol agents against postharvest diseases

Activity of the Yeasts Cryptococcus laurentii and Rhodotorula glutinis Against Post-harvest Rots on Different Fruits

Effect of the Biocontrol Yeast Rhodotorula glutinis Strain LS11 on Patulin Accumulation in Stored Apples.

Integrated control of blue mould using new fungicides and biocontrol yeasts lowers levels of fungicide residues and patulin contamination in apples