Progress 07/01/05 to 06/30/10
Outputs
Progress Report Objectives (from AD-416) 1. Conduct genetic mapping studies on Lr12 and Lr42. 2. Conduct marker-assisted selection for Karnal bunt resistance genes. 3. Develop resources and techniques for identification of targeted wheat mutants by TILLING. Approach (from AD-416) A collaborative program will be conducted to tag and identify genes that control avirulence in the wheat leaf rust fungus. Biolistics will be used to tag genes within the leaf rust fungus genome and sequencing will be used to identify candidate avirulence genes. Resistance genes for important wheat diseases will be genetically mapped and markers will be developed for marker-assisted selection. Microsatellites, amplified fragment length polymorphisms, and expressed sequenced tags will be used as sources of molecular markers. Physical maps will be constructed using genomic libraries and electrophoresis. An association mapping population has been assembled and phenotyped for seedling and adult plant resistance to stripe rust in the greenhouse and field. These data are currently being analyzed to identify loci that affect the severity of stripe rust. A serious outbreak of stripe rust occurred this past season in Kansas due to a new race of the pathogen with virulence to the Yr17 resistance gene. Sources of resistance to the new race have been identified that need to be characterized. Crosses have been initiated to create mapping populations for these sources of resistance. Wheat leaf rust resistance gene Lr12 is effective in adult plants, but not in seedlings. However, this gene can be effective in seedlings when the complementary gene Lr27 is also present. Our long term goal is to understand how Lr27 increases the effectiveness of Lr12. We determined the chromosome location of Lr12 and identified molecular markers that flank the gene. These may be useful for further fine mapping studies that could eventually lead to isolating the gene. A system has been developed using biolistics to test the function of genes from the leaf rust pathogen, P. triticina, as candidates for avirulence factors. The technique involves using the gene gun and co- bombarding two plasmids into the wheat seedlings. One plasmid contains the reporter gene and the other contains the avirulence gene candidate. The plasmids are shot into seedling leaf tissue of wheat isolines that contain different resistance genes. The level of expression of the reporter gene is measured. A reduction of the reporter gene expression is correlated with the induction of the hypersensitive disease resistance response. A positive reaction indicates that the gene may function as an avirulence factor in the host/parasite interaction. New diagnostic test for Wheat Streak Mosaic Virus and Triticum Mosaic Virus. Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are widespread throughout the southwestern Great Plains states. Both viruses have similar symptoms which makes visual identification almost impossible. The current ELISA method for detection of the viruses in plant samples uses antibodies specific to each of the viruses, but can be insensitive to low concentrations and depends on having high quality antiserum. The PCR method can be more sensitive and does not depend on antiserum. In both cases, only one of the viruses can be tested for per assay. The work that is being reported is a new multiplex method to test for both viruses at the same time in the same assay. Because of the higher sensitivity, it is superior to previous testing methods and can be used to more rapidly and more accurately diagnose these viruses. Progress on this agreement is monitored by regularly discussing program goals and approaches and by reviewing annual accomplishments reports.
Impacts
(N/A)
Publications
|
Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1. Conduct genetic mapping studies on Lr12 and Lr42. 2. Conduct marker-assisted selection for Karnal bunt resistance genes. 3. Develop resources and techniques for identification of targeted wheat mutants by TILLING. Approach (from AD-416) A collaborative program will be conducted to tag and identify genes that control avirulence in the wheat leaf rust fungus. Biolistics will be used to tag genes within the leaf rust fungus genome and sequencing will be used to identify candidate avirulence genes. Resistance genes for important wheat diseases will be genetically mapped and markers will be developed for marker-assisted selection. Microsatellites, amplified fragment length polymorphisms, and expressed sequenced tags will be used as sources of molecular markers. Physical maps will be constructed using genomic libraries and electrophoresis. Significant Activities that Support Special Target Populations Research continued on marker-assisted selection for resistance to Karnal bunt of wheat. Isogenic lines for resistance genes on chromosomes 4B, 5B, and 6B are in development. A new doubled haploid mapping population was tested for resistance at both CIMMYT and Punjab Agricultural University. A program to backcross resistance into the cultivar Jagger is at the third generation. The fungus Gibberella zeae (also known as Fusarium graminearum) causes Fusarium head blight of wheat and barley. This species is composed of multiple lineages that are morphologically similar and that are capable of crossing with each other to varying degrees. Chromosome rearrangements between the lineages could be an important barrier to fertility. We developed rapid methods for detecting chromosome rearrangements in this species. A new plant virus was discovered in Kansas and characterized. Physical properties indicated that the virus was flexuous rod shaped and about 800 nm in length. The coat protein of the virus was sequenced and it was determined that this virus belonged to the Potyvirus family and was given the name Triticum mosaic virus (TriMV). Sequence comparisons show that TriMV is significantly different from any other known virus and is distantly related to Wheat streak mosaic virus. The virus is transmitted by the wheat curl mite, but because of the divergence in sequence, we are proposing that TriMV be classified in a new family, Susmovirus. We are currently looking at samples taken from the lower Great Plains to determine the variation in sequence of TriMV. A manuscript is in preparation for the chromosome location of wheat leaf rust resistance gene Lr12 and a manuscript has been accepted for Lr42. Progress on this agreement is monitored by regularly discussing program goals and approaches and by reviewing annual accomplishments reports.
Impacts
(N/A)
Publications
|
Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) 1. Construct genetic populations of wheat for discovery of molecular markers for wheat resistance genes. 2. Conduct lipidomics analysis of genes up-regulated by rust resistance gene Lr34/Yr18 in wheat. 3. Test feasibility of using pheromones to control Fusarium graminearum on wheat. Approach (from AD-416) A collaborative program will be conducted to tag and identify genes that control avirulence in the wheat leaf rust fungus. Biolistics will be used to tag genes within the leaf rust fungus genome and sequencing will be used to identify candidate avirulence genes. Resistance genes for important wheat diseases will be genetically mapped and markers will be developed for marker-assisted selection. Microsatellites, amplified fragment length polymorphisms, and expressed sequenced tags will be used as sources of molecular markers. Physical maps will be constructed using genomic libraries and electrophoresis. Significant Activities that Support Special Target Populations This report serves to document research conducted under a specific cooperative agreement between ARS and Kansas State University, the Department of Plant Pathology. Additional details of this research can be found in the report for the parent project 5430-21000-005-00D, Genetic Enhancement for Resistanct to Biotic and Abiotic Stresses in Hard Winter Wheat. Leaf rust is a major disease of wheat that is economically important worldwide. Molecular markers were identified that flanked the wheat resistance gene Lr17a. These markers allow us to rapidly identify experimental lines that may carry Lr17a, which is thought to be common in hard winter wheat cultivars. Another approach is being used to investigate the process by which the wheat leaf rust pathogen, Puccinia triticina, infects and triggers the resistance pathway. Haustoria are the fungal structures that penetrate wheat leaf cells and withdraw nutrients. Five thousand clones of expressed genes from fungal haustoria were sequenced. These are being evaluated as potential avirulence factors that may trigger the plant defense system. The Lr34/Yr18 wheat resistance gene provides durable, adult-plant, slow- rusting resistance to leaf rust and yellow rust (stripe rust) of wheat. Patterns of gene expression were examined by microarray analysis in two pairs of wheat lines with or without Lr34/Yr18. Many genes with up- regulated expression in Lr34/Yr18 lines are associated with osmotic stress, cold stress, or seed maturation. These results support the hypothesis that Lr34/Yr18 has a novel mode of action. Several of these up- regulated genes could be useful as biomarkers for the presence of the Lr34/Yr18 gene in wheat lines. Progress on this agreement is monitored by regularly discussing program goals and approaches and by reviewing annual accomplishments reports.
Impacts
(N/A)
Publications
|
Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Kansas State University, Department of Plant Pathology. Additional details of this research can be found in the report for the parent project 5430-21000-005-00D of the Plant Science and Entomology Research Unit. This is a new project for FY2006. The objectives of this research project are: 1) Construct genetic populations of wheat for validation of molecular markers for Karnal bunt resistance genes; 2) Conduct functional analysis of genes up-regulated by rust resistance gene Lr34/Yr18 in wheat; 3) Determine role of pheromones on germination of Fusarium graminearum. Two putative KB resistance genes have been proposed for marker assisted breeding. The objectives are to verify the effect of these genes. We have F4 seed from individual F2 plants that carried markers for one or both genes. These materials are being used to develop near
isogenic lines for the resistance genes. Wheat leaf rust is one of the most important diseases of wheat worldwide. There are two groups of resistance mechanisms that have been described: hypersensitive resistance and slow rusting resistance. Gene expression in two pairs of isolines carry the slow rusting gene, Lr34, was studied using microarray chips. Gene expression patterns suggested a novel mechanism for the slow rusting phenotype. Fusarium graminearum is the major cause of Fusarium head blight of wheat and barley. In previous research, we found that the fungus produces sex pheromones that can affect sexual fertility and germination of spores. This system is being studied for possible control strategies.
Impacts
(N/A)
Publications
|
|