Progress 10/01/10 to 09/30/15
Outputs
Target Audience:Our research reached fellow academic scientists via publications and presentations at meetings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Over the course of the project, two undergraduate students wereengaged in these studies and received valuable training in plant pathology, agronomy, and the scientific method. One graduate student (Bec) has graduated with her PhD and is currently employed at the University of Florida. A second graduate student was engaged in cytological studies of Fusarium and Diplodia in corn sheaths and received training in microscopy and statistical analysis. How have the results been disseminated to communities of interest?The results were published in one research article and presented at several professional meetings to our academic colleagues. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We developed novel markers and used them to analyze a population of Fusarium graminearum from Kentucky (Bec et al., 2015). We learned that most of these isolates belonged to the dominant chemotype, but that they showed signs of being an isolated divergent population. Two species were recovered from wheat heads that had not previously been described from symptomatic wheat heads, but these did not cause symptoms when inoculated onto healthy wheat. These strains may colonize tissues secondarily that are killed by the scab fungus. This is significant because the other species produce different types of mycotoxins. Other work with Fusarium from this projectis still being repeated and written up for publication: one study suggested that the mating type genes of Fusarium graminearum are important for agressiveness to wheat: knockouts of the MAT1-1-1 and MAT1-2-1 genes were less aggressive than controls on winter wheat, but were not different from controls on corn stalks. These experiments are being repeated. Other experiments suggested that selfing or crossing among strains produced transgressive progeny that were more or less aggressive, or more or less toxigenic than their progenitor strains. These results are currently being written up for publication.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2015
Citation:
Bec, S., Ward, T., Farman, M., O'Donnell, K., Hershman, D., Van Sanford, D., and Vaillancourt, L.J. Characterization of Fusarium strains recovered from wheat with symptoms of head blight in Kentucky. Plant Disease 99: 1622-1632
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Our research reached fellow academic scientists via publications and presentations at meetings Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? One undergraduate student was engaged in these studies and received valuable training in plant pathology, agronomy, and scientific method. A graduate student who is first author on the paper (Bec et al., 2014) had already graduated. How have the results been disseminated to communities of interest? We published one paper (Bec et al., 2014) and also made a presentation at the NCC annual meetings at Purdue University, and at Iowa State University. What do you plan to do during the next reporting period to accomplish the goals? We will continue to evaluate this population using other types of markers, and investigate the infection of corn by these strains of Fusarium wheat blight fungi. We will work with Diplodia zeae to understand the role of mycotoxins in pathogenicity to maize tissues.
Impacts
What was accomplished under these goals?
We developed some novel markers and used them to analyze a population of Fusarium graminearum from Kentucky (Bec et al., 2014). We learned that most of the isolates belonged to the dominant chemotype, but that genetically they showed signs of being an isolated divergent population, suggesting there is not a lot of mixing of isolates from outside of Kentucky. We found two species that had not been previously described on symptomatic wheat heads, but these did not cause symptoms. We postulate that these colonize the tissues killed by the scab fungus. This is significant because these other species produce different types of mycotoxins.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2014
Citation:
Bec, S., Ward, T., Farman, M., O'Donnell, K., Hershman, D., Van Sanford, D., and Vaillancourt, L.J. Characterization of Fusarium strains recovered from wheat with symptoms of head blight in Kentucky. Plant Disease http://dx.doi.org/10.1094/PDIS-06-14-0610-RE
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: Corn and wheat growers, agribusiness, government regulatory agencies, food producers, food exporters. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Work on the project in Kentucky was performed by a visiting undergraduate from Brazil, who came to the University of Kentucky on a Science Without Borders fellowship from the Brazilian government. This undergraduate Genetics major obtained experience in Plant Pathology and in the culture of fungi and plants, which will greatly benefit her in her future academic and professional career. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? We will continue our experiments and extend them to intact stalk tissues to better understand the cytology of infection of maize by S. maydis wild type and mutant strains.
Impacts
What was accomplished under these goals?
A research collaboration was initiated between Dr. Lisa Vaillancourt at Kentucky and two other members of the NC-1183 committee, Dr. Charles Woloshuk at Purdue and Dr.Burton Bluhm at the University of Arkansas. The collaboration is to study the mechanisms of pathogenicity and mycotoxigenicity in Stenocarpella maydis. S. maydis causes Diplodia ear rot (DER) and Diplodia stalk rot (DSR) of maize, and it produces the mycotoxin Diplodiotoxin, which causes toxicosis in cattle and other animals that feed on the grain. DER and DSR impact three of the priority areas for U.S. agriculture (food security, food safety, and biofuels). There have been very few studies of the cytology of colonization of maize tissues by S. maydis, and nothing is known about the molecular mechanisms of pathogenicity. The lack of relevant knowledge is highly detrimental to our ability to develop new management tools for this important pathogen. The role of Kentucky in the collaboration will be to investigate the cytology of infection of sheaths and stalks by S. maydis. We have investigated early events in infection of living leaf sheaths by S. maydis. Spores germinated and began to penetrate via small non-melanized appressorium-like swellings within 24 hours. Host cells failed to plasmolyze even before visible penetration had occurred, and ahead of the advancing mycelium, suggesting that the fungus is producing a phytotoxin that kills the cells prior to colonization. Within 48 hours, tissue under the infection drop was completely collapsed and a brown lesion was easily visible. S. maydis thus behaves as a true necrotroph in leaf sheaths. Dr. Woloshukâs lab at Purdue identified an insertional mutant (strain 174) of S. maydis that accumulated a greenish pigment in culture medium. Southern analysis performed at Purdue indicated that the strain contained a single insertion in what appears to be the promoter region of a gene with high similarity to histidine kinases. We tested this mutant on corn leaf sheaths, and we saw that it germinated normally, but then failed to penetrate, growing instead over the surface. The host cells appear to remain intact, suggesting that this mutant does not produce the phytotoxin.
Publications
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: We are working to understand molecular relationships among mycotoxigenic fungi, and genes that quantitatively regulate pathogenicity and mycotoxin biosynthesis, with a focus on the Fusarium pathogens that cause Fusarium head blight (FHB) of wheat and barley. FHB results in contamination of grain with tricothecene mycotoxins, which are severely damaging to human and animal health, and which pose significant regulatory constraints to the producer. A combination of host resistance and fungicide treatment is the most effective strategy to lower the impact of FHB. To produce cereal varieties with durable resistance, and to maintain efficacy of fungicide treatments, we must understand the origin and degree of genetic diversity that is present in the pathogen population. New types of fingerprinting markers were developed and used to characterize a population of F. graminearum causing head blight on soft red winter wheat in Kentucky. A surprisingly high degree of genotypic diversity was revealed by these markers in these local populations. At least two novel Fusarium species, including one that appears to be undescribed, were found causing FHB symptoms in western Kentucky. Crosses among two genetically and phenotypically similar strains of G. zeae resulted in transgressive progeny that were significantly more aggressive and toxigenic than their parents in wheat heads. These strains did not differ in their aggressiveness to corn stalks, or in toxigenicity in culture. Analysis of co-segregation of SNP markers in bulked pools of aggressive versus nonaggressive siblings revealed approximately 10 genomic regions that were associated with aggressiveness and toxigenicity. These regions, which were rich in transporters and hypothetical proteins, will be the topic of future research. PARTICIPANTS: Graduate Student Sladana Bec. Undergraduate Student Jessica Lima. Research Technician Etta Nuckles. TARGET AUDIENCES: Corn and wheat growers, agribusiness, government regulatory agencies, food producers, food exporters. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Mycotoxins are fungal metabolites that can adversely affect animal and human health. Mycotoxins can be produced in grain during storage or processing, but are most frequently associated with fungal infection that occurs before harvest. Generally, a basal level of mycotoxins is always present in US grain; however, in some years, environmental conditions lead to localized or widespread outbreaks of mycotoxin contamination. Without an aggressive research program to prevent, treat, and contain outbreaks of mycotoxins in grain, US grain producers will suffer the consequences of reduced marketability of their products. The natural occurrence of mycotoxins in grain is an important security concern for the grain industry and end-users of grain; mycotoxins have been used as agents of terrorism, e.g. aflatoxin in Iraq. Stakeholders need cost-effective methods to predict, monitor, and minimize mycotoxin production in the field, and to detoxify mycotoxins and prevent further deterioration in contaminated grain. The scientists involved in this multistate, multidisciplinary research proposal work individually on mycotoxin issues related to their respective disciplines and areas of expertise. The production of mycotoxins by mycotoxigenic fungi represents a basic aspect of agricultural science. Improving our understanding of how mycotoxin biosynthesis is regulated will not only lead to novel treatment strategies, but may also advance our understanding of fungal pathogenesis in general.
Publications
- No publications reported this period
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: We are working to understand molecular relationships among mycotoxigenic fungi, and genes that quantitatively regulate pathogenicity and mycotoxin biosynthesis, with a focus on the Fusarium pathogens that cause Fusarium head blight (FHB) of wheat and barley. FHB results in contamination of grain with tricothecene mycotoxins, which are severely damaging to human and animal health, and which pose significant regulatory constraints to the producer. A combination of host resistance and fungicide treatment is the most effective strategy to lower the impact of FHB. To produce cereal varieties with durable resistance, and to maintain efficacy of fungicide treatments, we must understand the origin and degree of genetic diversity that is present in the pathogen population. In one part of our recent work we developed new genetic markers that can be used to monitor out-crossing and genetic diversity in the pathogen population. Application of these novel repetitive RFLP probes to a group of G. zeae isolates originating in and near Kentucky uncovered a surprisingly high degree of genotypic diversity in these local populations. It confirmed that the isolates used by the U.K. wheat breeding team were representative of the diversity in the state. It also revealed that there were at least two novel Fusarium species, including one that appears to be undescribed, causing FHB symptoms in western Kentucky. The RFLP probes were also shown to be useful as genetic markers for segregation analysis and could be used in the future to monitor outcrossing in field populations. In other work, we crossed two genetically and phenotypically similar strains of G. zeae and showed that this resulted in transgressive progeny that were significantly more aggressive and toxigenic than their parents. This was a surprising finding that showed that even when local strains appear to be similar in their pathogenicity, they have the potential to produce new and potentially more damaging strains by crossing. Crossing in G. zeae is under control of MATing type genes. We deleted the complete MAT1 locus, and separately the two mating specificities, MAT1-1-1, and MAT1-2-1. Deletion of MAT1-1-1 and MAT1-2-1 genes had a significant negative effect on aggressiveness to wheat, and on mycotoxin production in planta and in vitro, while deletion of the complete MAT1 locus has no effect on disease development nor on mycotoxin production. This exciting result reveals a previously unsuspected role for MAT genes in mycotoxin production that will be further explored in future research. PARTICIPANTS: PI Lisa Vaillancourt, Sladana Bec, Graduate Student (successfully defended her Ph.D. dissertation in 2011). TARGET AUDIENCES: Corn and wheat growers, agribusiness, government regulatory agencies, food producers, food exporters. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Mycotoxins are fungal metabolites that can adversely affect animal and human health. Mycotoxins can be produced in grain during storage or processing, but are most frequently associated with fungal infection that occurs before harvest. Generally, a basal level of mycotoxins is always present in US grain; however, in some years, environmental conditions lead to localized or widespread outbreaks of mycotoxin contamination. Without an aggressive research program to prevent, treat, and contain outbreaks of mycotoxins in grain, US grain producers will suffer the consequences of reduced marketability of their products. The natural occurrence of mycotoxins in grain is an important security concern for the grain industry and end-users of grain; mycotoxins have been used as agents of terrorism, e.g. aflatoxin in Iraq. Stakeholders need cost-effective methods to predict, monitor, and minimize mycotoxin production in the field, and to detoxify mycotoxins and prevent further deterioration in contaminated grain. The scientists involved in this multistate, multidisciplinary research proposal work individually on mycotoxin issues related to their respective disciplines and areas of expertise. The production of mycotoxins by mycotoxigenic fungi represents a basic aspect of agricultural science. Improving our understanding of how mycotoxin biosynthesis is regulated will not only lead to novel treatment strategies, but may also advance our understanding of fungal pathogenesis in general.
Publications
- No publications reported this period
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