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.
Scale-up tests for the control of brown rot (caused by M. fructicola) with bacterial and yeast antagonists were conducted on four major plum cultivars, Stanley, Obli’naja, Early Italian Prune, and President. More than 90% reduction in incidence of fruit decay originating from the wound infection was achieved with three antagonists. The wound response over time was determined for 18 apple accessions from the Kazakhstan and Central Asia collection in Geneva, New York, with regard to a resistance to blue mold (caused by Penicillium expansum) and the development of cytological changes characteristic of defense response reactions. Tests for the presence of reactive oxygen species (ROS), lignin, suberin, and callose after wounding indicate significant differences between resistant/immune, moderately resistant and susceptible accessions, with ROS production consistently higher in the most resistant/immune accessions. The other compounds increased at the later stages of wound healing in several instances; however, their presence was much less obvious and much more variable at all resistance levels. The effect of UV-C irradiation treatment on the microflora of strawberry leaves and fruit treated and untreated with two antagonists in a high tunnel culture was evaluated for the second consecutive year. The genetic based method (metagenomic DNA analysis using MiSeq sequencing) has been adopted to suit these types of samples in order to maximize the isolation of microbial DNA and increase resolution of the microbial composition. The final analysis of the microbial community is expected to be done by the end of this year. The second year experiment on the effect of UV-C irradiation treatment combined with two microbial biocontrol agents on the development of diseases on strawberries, as well as fruit yield and quality in high tunnel culture, is in progress and will be finished in two weeks. Transcriptional profiling of apple fruits in response to heat treatments has been conducted, and the role of induction of host defense mechansims vs. lethal heat effect on pathogen propagules was elucidated. Results have been published. The complete gene cluster responsible for producing patulin in the postharvest pathogen, P. expansum, was identified, and it was demonstrated that patulin does not play a role in the pathogenicity of P. expansum. Results were published.
1. The mycotoxin, patulin, is not related to blue mold virulence in apple. In addition to causing the postharvest disease, blue mold, in apple, Penicillium expansum also produces the mycotoxin, patulin, which represents a human health risk, especially in children. The relationship between patulin production and the virulence of blue mold, however, has remained elusive. A team of international researchers that included a USDA-ARS researcher at Kearneysville, West Virginia, were able to provide the complete genome sequence for P. expansum and identify the complete cluster of genes responsible for the synthesis of patulin. The ability to produce different amounts of patulin is not related to the virulence of the strain. The availability of the genome sequence provides an important new tool for plant pathologists to study the fungal biology of P. expansum, especially in regards to the production of mycotoxins. The finding of a lack of a relationship between patulin production and virulence represents a major accomplishment in understanding the biology of this economically important fungal pathogen.
Ballester, A., Marcet-Houben, M., Levin, E., Sela, N., Selma-Lazaro, C., Carmona, L., Wisniewski, M.E., Droby, S., Gonzalez-Candelas, L., Gabaldon, T. 2015. Genome, transcriptome, and functional analyses of Penicillium expansum provide new insights into secondary metabolism and pathogenicity. Molecular Plant-Microbe Interactions. 28(3):232-248.
Wisniewski, M.E., Spadoni, A., Guidarelli, M., Phillips, J., Mari, M. 2015. Transcriptional profiling of apple fruits in response to heat treatment: involvement of a defense response during P. expansum infection. Postharvest Biology and Technology. 101:32-48.
Sui, Y., Wisniewski, M.E., Droby, S., Liu, J. 2015. Responses of yeast biocontrol agents to environmental stress. Applied and Environmental Microbiology. 81:2968-2975.
Buron-Moles, G., Wisniewski, M.E., Vinas, I., Teixido, N., Usall, J., Droby, S., Torres, R. 2015. Characterizing the proteome and oxi-proteome of apple in response to a compatible (P. expansum) and a non-host (P. digitatum) pathogen. Journal of Proteomics. 114:136-151.