Location: Food Quality Laboratory
2025 Annual Report
Objectives
Objective 1: Elucidate genes and mechanisms involved in postharvest pathology of fruits, such as apple (NP303, C2, PS 2b).
Sub-objective 1.A. Functionally analyze 14 specific single-copy genes in Penicillium expansum using recombinant DNA technologies and evaluate mutants for defects in fruit decay, virulence, and patulin production.
Sub-objective 1.B. Evaluate P. expansum mutants to inhibit and/or outcompete wild type Penicillium spp. in vitro and under controlled storage conditions.
Objective 2: Develop and optimize new treatments during storage to enhance postharvest decay management of fruits. (NP303, C3, PS 3b).
Sub-objective 2.A. Determine the spore holding capacity of wooden and plastic storage bins and the ability of bin inoculum to manifest in postharvest decay for stored fruit.
Sub-objective 2.B: Examine and optimize new treatments to reduce fungal inoculum, combat antimicrobial resistance, and prevent rot of pome fruit during storage.
Approach
This plan will develop innovative methods, tools, and approaches to manage blue mold. Systems-based analysis of omics data has revealed virulence gene candidates expressed by Penicillium expansum during apple fruit decay. The basic research outlined in Objective 1 will verify virulence gene function in P. expansum, create new mutant antagonists, generate new fundamental information, and fill existing knowledge gaps. The applied research contained in Objective 2 will determine optimal approaches for bin sanitation, develop novel methods to reduce fungal inoculum responsible for decay, and evaluate new antagonists to block decay. Fundamental information and antagonists generated in Objective 1, coupled with practical outcomes from Objective 2, will be integrated to deliver timely solutions that impact science, industry, and the public. Optimal postharvest decay management will enhance the viability, strengthen longevity, and increase the competitiveness of the US in the global fruit market and reduce food loss and waste at commercial and consumer levels.
Progress Report
Significant progress has been made to abate food loss and waste due to the postharvest decay of stored apple and pear fruit. Research toward Objective 1 focuses on deleting two genes in the blue mold fungus to determine their roles in toxin production and fruit decay. Our findings show that they are likely not involved in decay or fungal- fungal interactions but likely play roles in degrading molecules produced by bacteria. However, we are in the process of making a blue mold strain with both genes deleted to rule out effects of one gene compensating for the other. We have also identified several mutants having increased sensitivity to toxins. We will use them to identify and design new approaches to block toxin production in the fungus. Generation of a blue mold fungus with green florescent protein is also in process, which once confirmed, will be used to assess efficacy of sanitation treatments conducted in later experiments for Objective 2.
For Objective 2, we showed that apple harvest and storage bin surfaces inoculated with blue mold spores can cause decay when in direct contact with wounded apple fruit. This scenario depicts what happens in storage at commercial packinghouses and shows the need to clean and sanitize the bins by providing direct evidence for stakeholders that dirty bins are problematic. Related progress has been made in collaboration with USDA scientists in Kearneysville, West Virginia, to understand the genetic basis of resistance to blue mold and bitter rot pathogens in wild apple germplasm. Multiple genes have been identified in resistant fruit and are being transferred to generate new apple breeding lines. These lines can then be used to transfer genes to commercial cultivars to impart resistance to blue mold and bitter rot. Work with USDA scientists in Beltsville, Maryland, have focused on novel compound discovery in blue mold isolates and revealed a compound that was evaluated to increase resistance in apple fruit to postharvest decay pathogens. Work to reduce losses on peanut and maintain safety focused on aflatoxin suppression using antagonistic bacteria and soil moisture levels were conducted in collaboration with USDA scientists in Dawson, Georgia. All work conducted on the project has implemented techniques and procedures aimed at making food more available, safe and ensure quality during storage so that the public has a secure food supply year-round.
Accomplishments
1. Wild apples unlock genes for blue mold resistance. Blue mold causes losses, increases waste and results in patulin contamination for processed fruit products. Blue mold is caused by a fungus, affects apple and pear fruit during storage, and all commercial cultivars are susceptible. ARS researchers in Beltsville, Maryland, in collaboration with scientists in Kearneysville, West Virginia, have discovered multiple genes associated with resistance using advanced technology. It was previously unknown if resistance genes existed in apple and or their identities. This breakthrough represents a new paradigm for the American agricultural industry and provides a new platform for scientists to develop new apple breeding lines and cultivars with durable postharvest blue mold control so that producers of American agricultural products can flourish.
2. Clean bins ensure decay free apple fruit. ARS researchers in Beltsville, Maryland, have shown that fungal spores on bin surfaces can be transferred to wounded apples and cause rot. Additionally, new ways of disinfecting storage bin surfaces have been tested and can be adopted by industry who are directly impacted and benefit from these research findings. Results from this study represent new information for industry and approaches to sanitize bins for chemical-free, environmentally friendly postharvest decay control so American agriculture can prosper.
Review Publications
Boeckman, N., Borba, M., Jurick Ii, W.M., Acimovic, S.G. 2025. Apple Bitter Rot: Biology, Ecology, Omics, Virulence Factors, and Management of Causal Colletotrichum Species. Molecular Plant Pathology. 26(1). Article e70050. https://doi.org/10.1111/mpp.70050.
Cardenas, D., Aguliar, C., Bhatta, U., Bugingo, C., Murray, S., Gazis, R., Miles, T., Jurick Ii, W.M., Naegele, R.P., Queseda, L., Thiessen, L., Cano, L. 2024. Omics-based comparison of fungal virulence genes, biosynthetic gene clusters, and small molecules in penicillium expansum and penicillium chrysogenum. Plant Disease. 11(1). Article e14. https://doi.org/10.3390/jof11010014.
Luciano-Rosario, D., Castro, J., Peter, K., Cox, K., Gaskins, V.L., Fonseca, J.M., Jurick Ii, W.M. 2024. Mold in, mold out: Storage bins harbor viable inoculum that can be reduced using novel sanitation methods to manage blue mold decay of apples. Postharvest Biology and Technology. 221. Article e113323. https://doi.org/10.1016/j.postharvbio.2024.113323.
Johnson, K., Douglas, R., Bradshaw, M.J., Brannen, P.M., Jurick Ii, W.M., Villani, S. 2025. Colletotrichum species causing Glomerella leaf spot and apple bitter rot in the southeastern United States exhibit disparities in relative frequency, morphological phenotype, and QoI sensitivity. Plant Disease. 109(3):579-592. https://doi.org/10.1094/PDIS-05-24-1006-RE.
Oehler, M.A., Kelly, N., Fonseca, J.M., Evensen, E., Park, E., Gu, G., Teng, Z., Luo, Y. 2025. Influence of supplementary blue and far-red light on the morphology and texture of Ocimum basilicum L. grown in controlled environments. Horticulturae. 11(3). Article e287. https://doi.org/10.3390/horticulturae11030287.
Evensen, E., Teng, Z., Mao, Y., Li, Y., Ortiz, I., Chen, P., Yang, T., Wang, Q., Fonseca, J.M., Luo, Y. 2025. Optimizing microgreen cultivation through post-crosslinked alginate-gellan gum hydrogel substrates with enhanced porosity and structural integrity. International Journal of Biological Macromolecules. 309(3). Article e142905. https://doi.org/10.1016/j.ijbiomac.2025.142905.