Progress 03/14/07 to 03/13/12
Outputs
Progress Report Objectives (from AD-416): Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416): Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. This is the final report for Project 5442-22000-042-00D, which has been replaced by bridging Project 5442-22000-047-00D. Substantial results were realized over the course of this project. The ability to reliably reproduce sugarbeet diseases in controlled settings is foundational for studying pathogen biology and disease resistance screening. Environmental parameters were assessed to optimize isolation and inoculation procedures for four important sugarbeet pathogens. Molecular techniques were developed to detect pathogens in diseased tissue, which helps to streamline the ability to quantify disease. To gain insight into the molecular interaction between sugarbeet and the important pathogens Cercospora beticola and Aphanomyces cochlioides, proteomic techniques were used isolate secreted proteins from both pathogens. Such proteins may be useful for future disease resistance screening strategies. Studies on the population biology of C. beticola showed that the fungus has many hallmarks of sexual reproduction and populations are genetically diverse, which may explain why the pathogen is able to readily develop fungicide resistance. In collaboration with ARS scientists in Fargo, ND, treatments with the plant hormone jasmonic acid were identified that reduced root rot to three important pathogens of sugarbeet. To find genes that are critical for this resistance response, next generation sequencing was utilized to identify sugarbeet genes differentially expressed after exposure to jasmonic acid, which may be valuable biomarkers for resistance screening. Research to determine the environmental parameters minimally and optimally required for infection with the soilborne pathogen Rhizoctonia solani were completed. This information is useful for sugarbeet growers, as it helps to determine the optimal timing for fungicide applications. The concepts and discoveries generated from this project plan have led to a more thorough understanding of sugarbeet pathology and host-pathogen interactions. The overall impact of this project is that sugarbeet growers and industry have new information on which to guide decisions concerning sugarbeet disease management, which will help to increase yield and profits. Accomplishments 01 Identification of a genetic mutation associated with fungicide resistanc Leaf spot, caused by the fungus Cercospora beticola, is the most importa foliar disease of sugarbeet and is controlled in part by the application of fungicides. However, fungicide resistance in C. beticola is a consta threat to sugarbeet growers and results in financial losses due to application of fungicides with reduced efficacy. In collaboration with plant pathologists at North Dakota State University, ARS scientists in Fargo, ND were the first to identify strains of C. beticola with resistance to a common class of fungicides. In addition, a specific genetic mutation that is associated with strobilurin resistance was identified. Knowledge of fungicide resistance will help guide decisions on choosing the optimum fungicide for effective disease control, which will decrease production costs and increase yields. 02 Identification of the sugarbeet disease organism in North Dakota. The sugarbeet cyst nematode is a devastating disease of sugarbeet. Knowledg of the occurrence and distribution of any plant pathogen is necessary fo disease control and prevention. In collaboration with plant pathologist at North Dakota State University, ARS researchers at Fargo, ND were the first to identify fields containing the sugarbeet cyst nematode in North Dakota. Since the sugarbeet cyst nematode is also an important pathogen of canola, this information is important for sugarbeet and canola grower so they can minimize future impacts and reduce inadvertent spread of thi pathogen.
Impacts
(N/A)
Publications
- Bolton, M.D., Secor, G.A., Rivera, V., Weiland, J.J., Rudolph, K., Birla, K., Rengifo, J., Campbell, L.G. 2012. Evaluation of the potential for sexual reproduction in field populations of Cercospora beticola from USA. Fungal Biology. 116:511-521.
- Zhong, S., Leng, Y., Bolton, M.D. 2012. Construction of hairpin RNA expressing vectors for RNA-mediated gene silencing in fungi. In: Bolton, M. D., Thomma, B.P.H.J. editors. Plant Fungal Pathogens: Methods and Protocols. New York, NY: Humana Press. p. 623-633.
- Bolton, M.D., Birla, K., Rivera-Varas, V., Rudolph, K.D., Secor, G.A. 2012. Characterization of CbCyp51 from field isolates of Cercospora beticola. Phytopathology. 102(3):298-305.
- Vargas, M., Loyola, C., Zapata, N., Rivera, V., Secor, G., Bolton, M.D., France, A. 2012. First report of root rot of Chicory caused by Phytophthora cryptogea in Chile. Plant Disease. 96(4):591.
- Dejonge, R., vanEsse, P., Maruthachalam, K., Bolton, M.D., Santhanam, P., Saber, M.K., Zhang, Z., Usami, T., Lievens, B., Subbarao, K.V., Thomma, B. P. 2012. Tomato immune receptor Ve1 recognizes effector of multiple fungal pathogens uncovered by genome and RNA sequencing. Proceedings of the National Academy of Sciences. 109(13):5110-5115.
- Nelson, B.D., Bolton, M.D., Lopez-Nicora, H.D., Niblack, T.L., Del Rio Mendoza, L. 2012. First confirmed report of sugar beet cyst nematode, Heterodera schachtii, in North Dakota. Plant Disease. 96(5):772.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416) Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. Progress was made in all three Objectives and their Sub-objectives. The ability to reproduce sugarbeet diseases in controlled settings has important implications for understanding pathogen biology and disease resistance screening. In Sub-objective 1a, protocols were developed that allowed easy and reproducible disease development to occur with two important sugarbeet pathogens. Parameters were optimized for zoospore production in Aphanomyces cochlioides, an organism typically recalcitrant for production of high numbers of zoospores in vitro. Since A. cochlioides zoospores typically initiate disease in nature, the ability to mass-produce zoospores in vitro is critical for disease screening and other greenhouse or growth chamber experiments. In addition, procedures were optimized Rhizomania disease reproduction in the greenhouse. This relied on diluting field soils containing the disease complex with potting soil at certain ratios. Rhizomania is caused by beet necrotic yellow vein virus and molecular techniques to distinguish this virus from others are important for the specific detection of Rhizomania in diseased plants. In Sub-objective 1b, primers were developed on single nucleotide polymorphisms in the RNA3 region of the BNYVV genome that distinguish it from other viruses causing disease in sugarbeet. In order to gain an understanding of effectors used to cause Aphanomyces root rot disease, experiments were initiated to study secreted proteins from A. cochlioides. In subobjective 2a, proteins were harvested from A. cochlioides growing in vitro utilizing media that has been shown to initiate secretion of effectors from other sugarbeet pathogens rather than protein samples harvested from infected sugarbeet that contain complex protein samples from both organisms. In Sub-objective 2b, Cercospora beticola isolates harvested from more than 10 fields were assessed for mating type and fungicide sensitivity. It was found that fields with reduced sensitivity to fungicides were predominated by one mating type or the other, likely a result of fungicide selection pressure and subsequent asexual reproduction by the fungus. In Sub-objective 3a, apoplastic fluid was harvested from sugarbeet infected with C. beticola. Proteins were harvested that contain sugarbeet defense-related and pathogen virulence- related proteins. Accomplishments 01 Disease management in sugarbeets. Evaluating resistance to fungicides i major focus for leaf spot disease management in sugarbeets. Utilizing fungicide sensitivity values obtained from over 3,500 isolates collected over four years, ARS scientists in Fargo, ND have shown that fungicide resistant isolates are becoming more common in commercial fields. In addition, no relationship between fungicide sensitivity and aggressivene exists, increasing the chances that fungicide resistance will become eve more common in the future if fungicides usage is not managed properly. The results of this study show that monitoring fungicide resistance is critical in order to prevent outbreaks of disease caused by fungicide- resistant isolates. This information will assist growers in selecting t optimum fungicide for efficient disease control thereby reducing production costs while also increasing yields. 02 Molecular characterization of CbCyp51, a gene encoding a fungicide targe in Cercospora beticola. Characterizing genes encoding proteins that are targeted by fungicides gives critical information on how fungicide resistance develops in plant pathogens. ARS scientists in Fargo, ND cloned CbCyp51 from C. beticola and sequenced the gene from 20 isolates with varying levels of resistance to fungicides to show that no mutation in the gene relate to fungicide sensitivity. However, the gene was over expression in resistant isolates. This information is useful for plant pathologists that wish to utilize molecular tools to monitor fungicide resistance in C. beticola. 03 Identification of Fusarium sp. novum, a new pathogen of sugarbeet. Identification of new and emerging diseases of sugarbeet is critical in order to develop resistant varieties before epidemics occur. ARS scientists in Fargo, ND used molecular tools to show that the new Fusari species causing the novel disease termed Fusarium yellowing decline is distinct from all other Fusarium species. This information is useful fo plant breeders for developing germplasm resistant to Fusarium yellowing decline and for plant pathologists to develop molecular probes for specific detection of this pathogen.
Impacts
(N/A)
Publications
- Gonzalez, M., Pujol, M., Metraux, J.P., Gonzalez-Garcia, V., Bolton, M.D., Borras-Hidalgo, O. 2011. Tobacco leaf spot and root rot caused by Rhizoctonia solani Kuhn. Molecular Plant Pathology. 12(3):209-216.
- Dejonge, R., Bolton, M.D., Thomma, B.P.H.J. 2011. How filamentous pathogens co-opt plants; the ins and outs of fungal effectors. Current Opinion in Plant Biology. 14:400-406.
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416) Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. Progress was made in all three Objectives and their Sub-objectives. In Sub-objective 1a, we made significant progress in the development of methods to reliably quantify pathogen levels in inoculated sugarbeet plants. The ability to reproduce sugarbeet diseases in controlled settings has important implications for understanding pathogen biology as well as future disease resistance screening strategies. Techniques to quantify pathogen levels relied on molecular technologies that have good lab-to-lab reproducibility and were shown to consistently quantify and discriminate pathogens from other microorganisms in soil and plant tissue. These technologies also address Subobjective 1b to develop protocols for the specific detection of important sugarbeet pathogens and vectors. Protocols and molecular tools were established to detect sugarbeet fungal and viral pathogens as well as vectors that transmit disease. The use of such technology allows for the detection of pathogens in the soil prior to disease onset, an important component of an integrated disease management strategy. Under Subobjective 2a, we made significant progress towards protein analysis of Cercospora beticola, the most economically important foliar pathogen of sugarbeet. By optimization of C. beticola growth conditions in vitro, we have made substantial gains in our efforts to induce pathogen protein production without the host plant present, thereby simplifying downstream protein identification. Techniques to confirm the biological role of pathogen proteins for sugarbeet colonization have confirmed that the developed protocols to induce protein production are appropriate. Under Subobjective 2b, we made significant progress in characterizing C. beticola mating type genes. Characterization of the mating type locus and mating type gene expression has important implications for population biology of this pathogen and the results suggest that sexual reproduction is likely in field populations and may explain the high levels of genetic diversity found in this species. Under Subobjective 3b, we have made significant progress towards determining efficacy for several fungicides using previously identified growth conditions that were optimized for Rhizoctonia root rot disease development in sugarbeet. These studies have identified new fungicide chemistries that can be added to the short list of fungicides that are currently used to combat this disease. Accomplishments 01 Identification of fungicides to control Rhizoctonia root and crown rot o sugarbeet. Rhizoctonia root and crown rot is an increasing problem for sugarbeet growers in the United States. Currently, chemical control is the primary means to control this disease. However, only one fungicide used in most sugarbeet growing areas, increasing the probability for fungicide resistance to develop in Rhizoctonia solani. Using conditions identified as optimal for disease development, ARS scientists at the Sugarbeet and Potato Research Unit in Fargo, ND screened several fungicides for efficacy to control this disease. The results have shown at least two additional fungicides are available that provide protection against this disease. The information is useful for growers through the expansion of fungicide possibilities to control this disease. 02 Characterization of the mating type locus. Cercospora beticola is the causal pathogen that is responsible for sugarbeet leaf spot; a disease costing sugarbeet producers millions of dollars annually. Field isolate of Cercospora beticola are well-known for high levels of variability, particularly with regard to morphological characteristics and fungicide resistance. Such variability typically only occurs in fungal species th reproduce sexually. Despite this, C. beticola is only known to reproduc asexually. ARS scientists at the Sugarbeet and Potato Research Unit in Fargo, ND have characterized the mating type genes of C. beticola, genes that are known to be required for sexual reproduction. Our results suggest that C. beticola mating type genes are still active and may play role in sexual reproduction of this fungus. This information is useful for plant breeders when selecting parents for developing disease resista sugarbeet and is useful for plant pathologists to help explain how C. beticola is able to gain resistance to fungicides.
Impacts
(N/A)
Publications
- Weiland, J.J., Chung, K., Suttle, J.C. 2010. The Role of Cercosporin in the Virulence of Cercospora ssp. to Plant Hosts. In Lartey, R.T., Weiland, J.J., Panella, L., Crous, P.W., Windels, C.E., editors. Cercospora Leaf Spot of Sugar Beet and Related Species. St. Paul, MN: The American Phytopathological Society. p. 109-117.
- Bolton, M.D., Panella, L.W., Campbell, L.G., Khan, M.F. 2010. Temperature, Moisture, and Fungicide Effects in Managing Rhizoctonia Root and Crown Rot of Sugar Beet. Phytopathology. 100(7):689-697.
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416) Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. Significant Activities that Support Special Target Populations Research to design primers to distinguish Aphanomyces cochlioides and Rhizoctonia solani has resulted in the successful development of species and sub-species specific primers. Using these primers, PCR conditions have been optimized for specificity and reliability to distinguish R. solani sub-species AG 2-2 IIIB and AG 2-2 IV, and A. cochlioides from other sugarbeet pathogens. Methods to isolate and purify apoplastic fluid from Cercospora beticola-infected sugarbeet leaves have been optimized. In collaborative research with colleagues at North Dakota State University, a multi-year study to determine the occurrence and frequency of mating type genes in field isolates of C. beticola has been completed. Research to determine the environmental parameters affecting the severity of R. solani infection has been completed in collaboration with colleagues at North Dakota State University. Technology Transfer Number of New/Active MTAs(providing only): 1
Impacts
(N/A)
Publications
- Bolton, M.D. 2009. Primary Metabolism and Plant Defense - Fuel for the Fire. Molecular Plant-Microbe Interactions. 22(5):487-497.
- van Esse, H.P., van't Klooster, J.W., Bolton, M.D., Yadeta, K.A., Van Baarlen, P., Boeren, S., Vervoort, J., de Wit, P.J.G.M., Thomma, B.P.H.J. 2008. The Cladosporium fulvum Virulence Protein Avr2 Inhibits Host Proteases Required for Basal Defense. The Plant Cell. 20:1948-1963.
- deSilva, A.P., Bolton, M.D., Nelson, B.D. 2009. Transformation of Sclerotinia Sclerotiorum with the Green Fluorescent Protein Gene and Fluorescence of Hyphae in Four Inoculated Hosts. Plant Pathology. 48:487- 496.
- DeTemmerman, N., Anfinrud, M., Meulemans, M., Rick, K., Burkholz, A., DeBruyne, E., Weyens, G., Barnes, S., Horemans, S., Lefebvre, M., Bolton, M.D. 2009. Rhizomania Resistance in the Tandem Sugar Beet Variety. International Sugar Journal. 111(1325):313-317.
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Progress 10/01/07 to 09/30/08
Outputs
Progress Report Objectives (from AD-416) Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416) Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. Significant Activities that Support Special Target Populations Research to determine the optimum temperature for chemical control of Rhizoctonia solani have been initiated in collaboration with colleagues at North Dakota State University. To facilitate sugarbeet germplasm development, greenhouse methods to screen for resistance to Aphanomyces cochlioides are being developed. Research to identify effector proteins in the important sugarbeet pathogens Cercospora beticola and Aphanomyces cochlioides has been initiated and methods to isolate apoplastic fluid have been optimized. This research addresses National Program 303: Components 2 (Pathogen Biology, Virulence Determinants, and Genetics of the Pathogen) ,3 (Disease Resistance in New Germplasm), 4 (Biological and Cultural Strategies for Sustainable Disease). Technology Transfer Number of New/Active MTAs(providing only): 1
Impacts
(N/A)
Publications
- Bolton, M.D., Thomma, B.P.H.J. 2008. The complexity of nitrogen metabolism and nitrogen-regulated gene expression in plant pathogenic fungi. Physiological and Molecular Plant Pathology. 72:104-110.
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Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) Three of the most significant field diseases of sugarbeet in the U.S. are root rot, caused by Aphanomyces cochlioides; Rhizomania, caused by a fungal/viral complex; and wilt, caused by the sugarbeet cyst nematode, Heterodera schachtii, and concomitant infection by Fusarium fungi. The objectives of this project are to investigate methods to reproduce the field diseases of these pathogens in controlled environments, to develop qualitative and quantitative detection reagents and protocols for these organisms, and to determine genetic changes in viruses of the Rhizomania complex that condition heightened virulence to sugarbeet. Since the incorporation of natural genetic resistance into crops remains the most cost-effective strategy for disease control, an additional objective of the project is to obtain molecular genetic tags for disease resistance genes in sugarbeet in collaborative studies with ARS sugarbeet geneticists and pathologists. Approach (from AD-416) Gradients of saturation across seedbeds will be tested as a means to evaluate sugarbeet varieties with known resistance to Aphanomyces cochlioides using stand loss as a measure of disease severity. Protocols for the inoculation of sugarbeet with Polymyxa betae will be modified to select for clonal isolates of the organism, an aspect lacking in past studies on this pathogen. Probe primers will be designed to perform in conjunction with specific primer sets in the development of real-time PCR (qPCR) methods for quantifying these pathogens in soil and plant samples. Disruptions (insertions) in the chromosomes of beet black scorch virus and beet necrotic yellow vein virus will be engineered in efforts to determine the role of virus genes in pathogen virulence. Plants typed for either resistance or susceptibility to the sugarbeet cyst nematode and Fusarium stalk blight will be subjected to DNA fingerprinting for generation of molecular markers linked to resistance genes. BSL-1 certified 11-9-2006. Accomplishments None. This CRIS Project was approved through the OSQR peer review process on January 30, 2007 and the scientific staff position has been vacant since February 16, 2007. Recruitment for position is currently ongoing.
Impacts
(N/A)
Publications
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