1a. Objectives (from AD-416)
Develop reliable high throughput methods of phenotyping common scab resistance. Accelerate selection of breeding lines combining chip processing, late blight and scab resistance.
1b. Approach (from AD-416)
In cooperation with Sklarczyk Minitubers, Johannesburg, MI, a hydroponic tuberization system (nutrient film technology or NFT) has been set up at Michigan State. Initial experiments will be conducted to examine how nutrient solution pH, inoculum concentration and timing of inoculation influence scab lesion development on a set of four lines that differ in their scab reaction under field conditions. The validated NFT system will be further used to evaluate commonly grown varieties and breeding material, as well as for phenotyping scab tolerance in populations developed during other research projects. We will evaluate 117 crosses comprising about 500 selections segregating for common scab resistance, late blight resistance and chip-processing to select optimal lines with good agronomic traits that also combine these three characteristics for further advancement in our breeding program. In addition, 53 lines that may combine scab resistance, late blight resistance and chip-processing will be evaluated in replicated trials for agronomic performance in 2009 and also screened in replicated trials for late blight and scab resistance.
3. Progress Report
Screening potato breeding lines for susceptibility to common scab requires several years of field tests, replicated in multiple geographic locations. To identify quicker and more reproducible methods of screening for common scab resistance, a nutrient film technology (NFT) hydroponic mini-tuberization system has been set up in a greenhouse at Michigan State University. Initial experiments were done to optimize potato tuberization to establish suitable procedures for inoculating tissue culture potato plants with Streptomyces scabies. The susceptible variety Atlantic developed scab lesions when grown in vermiculite inoculated with S. scabies. Replicated trials on 12 (susceptible and resistant) breeding lines and cultivars that ranged in their response to scab in previously conducted field and greenhouse trials are now being set up. The NFT scab results will be compared to previous field and greenhouse trial results. To accelerate selection of potato lines combining chip processing quality with late blight and common scab resistance, early generation breeding materials will be phenotyped for these 3 traits in the field this season. Of a total of 117 crosses comprising about 500 selections segregating for these qualities, 59 selections from 53 different crosses that may combine scab resistance, late blight resistance and chip-processing were evaluated in replicated trials for agronomic performance in 2009. This field season we are testing additional lines in our scab and late blight nurseries, and repeating testing of the best of the lines from 2009. Chip-processing will again be evaluated following selection in the field. The best lines will be targeted toward advanced testing and future on-farm testing. The impact of this research is that it contributes potentially speedier methods of evaluating common scab resistance, and it speeds selection of potato breeding material incorporating multiple valuable traits. Progress was monitored by regular telephone calls, exchange of e-mails, and receipt of a preliminary written report containing experimental results.