Molecular and Cellular Biology Research Interests:
Research Area 1
Gene manipulation of peanuts with resistant genes against Aspergillus sps using Agrobacterium tumefaciens.
Georgia, Florida and Alabama are known for their peanut cultivation and Georgia alone produces approximately 50% of peanuts in the United States with several hundred million dollars in revenue. In spite of strict control measures, the peanut industry continues to suffer economic loss due to aflatoxin contamination from Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are carcinogenic to humans and other animals, and accumulation of aflatoxins in peanut kernels can influence marketing of peanut and peanut products. Breeding for resistant varieties against this mold, has not been very promising, as evidenced by serious economic losses in the peanut market due to aflatoxin outbreaks year after year. Traditional breeding is a costly, laborious and a time consuming process as opposed to developing resistant peanut cultivars which maintain a low level of aflatoxin contamination. The goal of my research is to transform peanuts with resistant genes such as chitinase and β-1, 3-glucanase against A. flavus, the most common aflatoxin producing Aspergillus sps. in peanuts and other food and agricultural products.
Research also includes expression of these pathogenesis-related (PR) proteins such as chitinase and β-1, 3-glucanase and aflatoxin at cellular and subcellular levels in susceptible, tolerant, and transgenic peanut lines by immunocytochemical approaches. The intellectual merit of this research is to produce basic information about a little studied area, the characterization of PR proteins and disease resistance in transgenic peanuts. Basic molecular and biochemical studies in tolerant/transgenic peanut varieties will provide information on tolerance/resistance and on prevention of aflatoxin accumulation in peanuts. The in Situ localization of induced molecules in the presence of foreign genes from the cyto and immunocytochemical approaches will form the basis for future research in the development of biological control alternatives for A. flavus in peanuts. Broader impacts include the research’s potential to make progress in developing an effective approach to eliminating aflatoxin accumulation in peanuts. Moreover, developing new peanut transgenic cultivars with resistance using genetic engineering will have great potential in breeding resistance to A. flavus infection, and the problem of aflatoxin management could be solved if peanut cultivars are resistant against A. flavus colonization. Reducing a lower level of aflatoxin or preventing the production of carcinogenic toxin is certainly beneficial to peanut consumers.
Research Area 2
In addition to gene manipulation to control Aspergillus sps in peanuts, my research also focuses on use of plant based antimicrobial compounds such as essential oils/vapors and probiots to prevent Aspergillus contamination. According to FAO, approximately 25 million dollars are lost per year due to the contamination of peanuts by Aspergillus spp. and aflatoxins. A. flavus is the common fungus contaminating peanuts and destroying peanuts shells before they are harvested and produce aflatoxins which are known to be both highly toxic and carcinogenic, threatening humans, livestock and crops worldwide. Prevention and decontamination of the mycotoxigenic Aspergillus species and aflatoxins in peanuts is of paramount importance because, it is the world's fourth most important source of edible oil and third most important source of vegetable protein. At present, disease management in crop fields is practiced solely through adaptation of suitable cultural practices such as rotation, use of quality seed and fungicides and altering the time of planting. In addition to post-harvest procedures through use of chemicals for aflatoxin prevention, several other viable means to prevent the contamination process in crops before harvest are being undertaken in several laboratories around the world. Use of chemicals to control Aspergillus species has proven to be unsuccessful and detrimental to the environment. Further, many disadvantages are associated with the use of chemical preservatives as antifungal agents. Extensive use of these substances might produce several side effects such as carcinogenicity, teratogenecity and toxicity to consumers.
There is an increasing interest in use of alternative antimicrobial agents from plants to control toxigenic Aspergillus species. One such alternative is the use of natural plant products with antifungal properties. Recently, there has been considerable interest in the use of essential oils and their vapors from aromatic plants with antimicrobial activities for controlling Aspergillus species in peanuts. The main reason for considering the essential oils and the vapors, as antifungal agents, is that the majority of the essential oils are classified as Generally Recognized As Safe (GRAS), their use in foods as preservatives is often limited due to flavor considerations. This will obviously reduce exposure to the legal, environmental, and public safety hazards . While the quest to control Aspergillus spp., using both conventional and advanced techniques continues here in Georgia and US as a whole, the aflatoxin contamination in peanuts is far from over. This study identifies edible plants based essential oils for their antifungal properties against A. flavus and A parasiticus. This research is a novel idea to pest management program and aflatoxin contamination peanuts. Moreover, the use of essential oil as antimicrobial agents, over protectant fungicides or developing a resistant cultivar either by conventional or genetic engineering may apply directly to the growers’ margin of profit and at the same time keeping peanut consumers healthy.
In parallel with my research goals to develop transgenic healthy peanuts, my goal is also to train and engage undergraduate and graduate students in hands-on experiments in molecular, biochemical, immunocytochemical, tissue culture techniques, and the use of antimicrobial compounds as biological control agents to control fungal pathogens in economically important crops.