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.
The composition of major phenolic compounds in blue mold resistant and susceptible wild apples from Kazakhstan and other parts of the world, as well as in susceptible 'Golden Delicious' was determined. Principle compound analysis of the results indicate clustering of susceptible wild apples with 'Golden Delicious' and distant clustering of the resistant wild apples. These results lead us to our current work (in progress) on the indepth characterization of phenolic compounds produced in response to apple wounding, as the wounds are the main court of entry for the fungus causing blue mold. Recently developed UV-C treatment followed by dark period is a promising alternative to synthetic fungicides for controlling strawberry diseases. However, this treatment decimates microbial populations creating a microbial vacuum that may be populated by pathogens. To prevent this, beneficial native plant microbes can be applied after the UV-C/dark treatment. We provided a baseline description of the culture independent bacterial microbiome associated with strawberries grown in a high tunnel in response to UV-C/dark and UV-C/dark-microbe disease management strategies. DNA was purified from leaf and fruit surfaces of strawberries from each treatment, amplified, and 16S rRNA gene amplicons were sequenced using the Illumina MiSeq V3 platform. Data were analyzed using the QIIME and Resphera Insight software. Principal component analyses of 16S rRNA gene amplicons showed no distinct taxonomic profiles for the controls, or the UV-C/dark or UV-C/dark-microbe treatments. These results will be used to better understand the impact of specific strawberry disease management practices on the distribution of bacterial microbiota associated with fruit and leaf surfaces. Twelve beneficial yeasts and bacteria, originally isolated from plum and nectarine fruit, and shown to be inhibitory to the brown rot fungus, were tested for control of brown rot on four plum cultivars, 'Obli’naja', 'Early Italian Prune', 'Stanley', and 'President', in scale-up postharvest dip application experiments. The incidence of decay was reduced by as much as 94%; however, it was dependent on the cultivar. Overall, a high level of decay control by most antagonists was achieved on 'Stanley' and 'President', and to a lesser degree on 'Obli’naja', and least on 'Early Italian Prune'. Thus, specifically selected antagonists will have to be used on some cultivars (e.g. 'Early Italian Prune'), while on many other cultivars, brown rot could be controlled by a range of antagonists. The ability of chitosan and glycochitosan to prevent tuber rots in ginger plants was demonstrated. Results have been published. Effector genes, code for proteins that interfere with host defense systems, were identified in Penicillium expansum, and their interacting apple proteins were identified using yeast two hybrid technology. These preliminary results represent a major breakthrough in understanding virulence and pathogenicity in P. expansum, the causal agent of blue mold in apple.
1. Novel UV-C/dark treatment for controlling strawberry diseases. Strawberry production in high and low tunnel culture presents significant challenges to disease control. ARS researchers in Kearneysville, West Virginia, found UV-C irradiation in strawberry plants, followed by a four-hour dark period, can control gray mold and anthracnose infection of strawberry fruit. This technology represents an effective alternative to the use of synthetic, chemical fungicides and its use is especially applicable to urban horticulture and high/low tunnel production systems.
Cheng, Z., Chi, M., Li, G., Chen, H., Sui, Y., Wisniewski, M.E., Norelli, J.L., Liu, Y., Liu, J. 2016. Heat shock improves stress tolerance and biocontrol performance of Rhodotorula mucilaginosa. Biological Control. 95:49-56.
Janisiewicz, W.J., Evans, B.E., Bauchan, G.R., Chao, C.T., Jurick II, W.M. 2016. Wound responses of wild apples suggest multiple resistance mechanism against blue mold decay. Postharvest Biology and Technology. 117:132-140.
Liu, Y., Wisniewski, M.E., Kennedy, J.F., Jiang, Y., Tang, J., Liu, J. 2016. Chitosan and oligochitosan enhance ginger (Zingiber officinale Roscoe) resistance to rhizome rot caused by Fusarium oxysporum in storage. Carbohydrate Polymers. 151:474-479.
Janisiewicz, W.J., Takeda, F., Glenn, D.M., Camp, M.J., Jurick II, W.M. 2016. Dark period following UV-C treatment enhances killing of Botrytis cinerea conidia and controls gray mold of strawberries. Phytopathology. 106(4):386-394.
Chen, H., Cheng, Z., Wisniewski, M.E., Liu, Y., Liu, J. 2015. Ecofriendly hot water treatment reduces postharvest decay and elicits defense response in kiwifruit. Environmental Science and Pollution Research. 22:15037-15045.