1a.Objectives (from AD-416)
A new late blight isolate, called blue 13 with fungicide resistance has recently taken a dominant position in Phytophthora populations in the United Kingdom, the Netherlands, Germany and France. These new isolates are more aggressive compared to the old population. While this new isolate is not yet present in the United States, we need to be prepared with germplasm that is resistant to highly virulent strains.
Our specific objectives are to:
1. Conduct transformations with candidate sequences of a putative S. microdontum R-gene.
2. Identify functional orthologs of the late blight R-gene RB from disease resistant wild germplasm and test the functionality of these genes using a transient expression assay.
3. Evaluate the late blight resistant potato advanced breeding lines including the varieties 'Defender' and 'Jacqueline Lee' for resistance to Blue 13 and identify the presence of genes that recognize P. infestans effectors.
4. Evaluate the effect of pyramiding the RB with conventionally bred late blight resistant lines.
1b.Approach (from AD-416)
Test the resistance phenotype of transgenic plants with the S. microdontum gene to P. infestans isolates collected from the United States and Guatemala.
This project is focused on understanding the molecular interactions determining resistance in potato to the late blight pathogen Phytophthora infestans. Resistance to this disease is present in many wild species of potato and some resistance traits have been incorporated into cultivated potato varieties. However, little is known about the genes that have been transferred and what they recognize to elicit resistance. A graduate student has been trained on the methods involved in testing whether the plant contains a major resistance gene. We are in the process of evaluating cultivated potato varieties 'Defender' and 'Jacqueline Lee' for their ability to recognize one of a set of specific protein molecules derived from P. infestans. Our set of P. infestans proteins includes approximately 75 candidates. A positive response will indicate that the plants contain the corresponding resistance gene. This response can then be used as a marker to track resistance in segregating populations, alleviating the need for field trials to test for resistance by inoculating with the pathogen. The scientists and students associated with the project meet on a bi-weekly basis to discuss progress on the project.