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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Research Project #423158


Location: Innovative Fruit Production, Improvement, and Protection

2017 Annual Report

1: Develop effective biologically based systems for managing postharvest disease of temperate fruit crops. 1.A. Establish a biocontrol system to control brown rot of stone fruits. 1.B. Determine the cytological aspects of resistance in wild apple fruit from Kazakhstan to blue mold. 1.C. Develop a biocontrol management system for gray mold and anthracnose of strawberry high-tunnel production utilizing UV-C and microbial antagonists. 2: Develop knowledge base on the biology of postharvest biocontrol systems for use in selecting superior antagonists and to improve the overall efficacy of biocontrol agents. 2.A. Determine the effect of yeast induced reactive oxygen species (ROS) on host resistance. 2.B. Determine mechanisms associated with biocontrol of brown rot of stone fruits.

Research is focused on reducing the need of using postharvest fungicides in fruit production. It includes developing postharvest biological control of brown rot latent infections of stone fruits, basic studies on biocontrol systems, explaining the cytological basis for the resistance of Malus sieversii (‘Kazak’) apples to blue mold, and using LED lights to reduce gray mold and anthracnose of strawberries in high tunnel cultures. The seasonality of fruit availability allows the project to address the different objectives. Biocontrol studies on stone fruits will be conducted in early summer, resistance research on Kazak apples in the fall, and biocontrol studies on strawberry during the winter. Biocontrol of latent infections will include scale-up tests under simulated commercial conditions and research explaining the mechanism of biocontrol. Resistance studies of ‘Kazak’ apples will focus on characterizing the biochemistry of wound responses. Strawberry research will involve determining the effect of different UV-LED wavelengths on survival of B. cinerea and Colletotrichum spp., and epiphytic microflora, its effect on plants, and the use of selected LED in combination with antagonists to reduce gray mold and anthracnose. Basic research on yeast-based biocontrol systems will determine the effect of reactive oxygen species (ROS) on the efficacy of yeast antagonists and the ability of yeast ROS to induce defense systems in apple. This research will give growers alternative biological tools to combat fruit diseases, improve the efficacy of biocontrol systems, and in the case of the Kazak work, provide new information for the basis of postharvest disease resistance in apple germplasm that can be used in breeding programs.

Progress Report
Identifying sources of resistance to blue mold would reduce the need for the application of postharvest fungicide sprays. In this project, the cytological responses of wild apples from Kazakhstan were determined that they were associated with the resistance response to blue mold. The cytological responses had some similarities but also major differences with the resistance response observed in immature apples. Higher concentrations of phenolic compounds were also observed in the resistant, wild apples. The significance of those differences and their potential use as a selection criteria in breeding programs will be investigated in the upcoming research project. Developing alternative methods of disease control for fruit crops grown in protected culture (greenhouses, high tunnels, etc.) is essential as chemical fungicides currently approved for use in these settings is limited. A novel strategy using UV-C irradiation followed by a dark period was developed to control major diseases of strawberries such as gray mold, powdery mildew and black spot in high tunnels and greenhouses. This new technology greatly reduces the amount of energy needed to kill pathogens, eliminates problems of UV-C damage to plants as well as the need for a reentry period required after application of fungicides, and is compatible with organic production. It could also be easily adapted to other systems of indoor production of strawberries as well as other fruits and vegetables, like those using vertical farming systems in many urban areas of the Northeast. Pilot tests are in progress for using this technology in high table strawberry production. The effect of this technology on the induction of resistance in the plants to the diseases and on colonization of strawberry plants by microbes will be investigated in the upcoming research project. Developing effective biological control of brown rot of stone fruit has been difficult and has required additional research. In the current project, factors affecting attachment of the fungus to surfaces, a process that is essential to initiating the disease were identified and the most effective microbial antagonists were selected as potential biocontrol agents. Although significant reduction in fruit decay was achieved, levels of control were below industry standards. The utilization of pressure infiltration of a biocontrol agent along with a Generally Regarded as Safe (GRAS) disinfectant compound will be explored in the upcoming research project. A systems approach to biological control recognizes that the factors that define and modulate the performance of the system are comprised of the biocontrol agent, the pathogen, the host, and the environment. All these factors need to be taken into account when developing an effective biocontrol system. In the current project, the role of reactive oxygen species (ROS) in the biocontrol was studied in a comprehensive manner. Studies indicated that yeast antagonists are resistant to high levels of ROS, and stimulate the host (fruit tissues) to produce ROS when they are applied. The host and yeast produced ROS stimulates defense mechanisms in fruit tissues and is also toxic to pathogen propagules (spores) and developing hyphae. The studies also demonstrated that sublethal treatment of yeast biocontrol agents with heat, ROS-generating compounds, and osmoticums, such as glycine betaine, can make them more stress resistant and improve their efficacy. This information can be used in the development of superior formulations of the biocontrol agent and should improve the effectiveness of their performance in variable and stressful environments, as one would find in a packinghouse.

1. Postharvest disease resistance in wild apple species. Several wild apple accessions from Kazakhstan and two from other parts of the world were identified that are highly resistant to blue mold decay caused by Penicillium expansum. Studies on the wound responses of these apples to infection by this fungus suggest multiple mechanisms of resistance including preexisting immunity. The phenolic composition of extracts from mature wild apples resistant and susceptible to blue mold support the potential relationship between the phenolic content of wild apples and their resistance to P. expansum. Resistant apple genotypes had higher concentrations of procyanidins, dihydrochalocone, flavonols, and hydroxycinnamic acids. These findings may lead to their potential use as selection traits for apple breeders wanting to incorporate blue mold resistance into their breeding stock and cultivar development.

Review Publications
Sun, J., Janisiewicz, W.J., Evans, B.E., Jurick II, W.M., Chen, P. 2017. Composition of phenolic compounds in wild apple with multiple resistance mechanisms against postharvest blue mold decay. Postharvest Biology and Technology. 127:68-75.
Jurick II, W.M., Macarisin, O., Gaskins, V.L., Park, E., Yu, J., Janisiewicz, W.J., Peter, K.A. 2016. Characterization of postharvest fungicide-resistant Botrytis cinerea isolates from commercially stored apple fruit. Phytopathology. 107:362-368.
Wisniewski, M.E., Norelli, J.L., Droby, S., Liu, J., Schena, L. 2016. Alternative management technologies for postharvest disease control: the journey from simplicity to complexity. Postharvest Biology and Technology. 122:3-10.
Abdelfattah, A., Wisniewski, M.E., Nicosa, M., Cacciola, S.O., Schena, L. 2016. Metagenomic analysis of fungal diversity on strawberry plants and the effect of management practices on the fungal community structure of aerial organs. PLoS One. DOI: 10.1371/journal.pone.0160470.
Abdelfattah, A., Wisniewski, M.E., Droby, S., Schena, L. 2016. Spatial and compositional variation in the fungal communities of organic and conventionally grown apple fruit at the consumer point-of-purchase. Horticulture Research. DOI: 10.1038/hortres.2016.47.
Droby, S., Wisniewski, M.E., Teixido, N., Spadaro, D., Jijakli, H. 2016. The science, development, and commercialization of postharvest biocontrol products. Postharvest Biology and Technology. 122:22-29.
Janisiewicz, W.J., Takeda, F., Jurick II, W.M., Evans, B.E., Glenn, D.M., Camp, M.J. 2016. Use of low-dose UV-C irradiation to control powdery mildew caused by Podosphaera aphanis on strawberry plants. Canadian Journal of Plant Pathology. 38:430-439.