Location: Crop Improvement and Protection Research
Project Number: 2038-21530-001-12-I
Project Type: Interagency Reimbursable Agreement
Start Date: Sep 1, 2013
End Date: Aug 31, 2017
Objective 1: Collect and screen Lactuca accessions for resistance to race 2 V. dahliae. Objective 2: Develop high throughput screening methods for assessing foliar disease severity using remote sensing technology. Objective 3: Map QTL in partial resistant (PR) × PR and PR × susceptible crosses for race 2 V. dahliae resistance and horticultural characteristics hypothesized to be correlated with resistance. Objective 4: Select for race 2 V. dahliae resistant iceberg cultivars in field and greenhouse experiments.
Approach 1: We will screen Lactuca germplasm for resistance to race 2 isolate Vdls17 in greenhouse and field experiments using previously collected accessions and newly collected accessions from the lettuce center of diversity. Accessions resistant to Vdls17 will be evaluated for resistance against a diversity of race 1 and race 2 isolates. Approach 2: We will use field and greenhouse experiments to determine if a spectroradiometer (visible and near infrared spectra) and thermal imaging can discriminate diseased and healthy plants. Approach 3: i) We will assess disease resistance and horticultural characters in field and greenhouse experiments in populations from multiple crosses. We already have populations from eight crosses to use in identifying resistance QTL. ii) In crosses that segregate for resistance, we will construct molecular marker linkage maps to use in QTL mapping. iii) We will identify SNP markers that are informative across the genepool and flanking the QTL that are independent of plant morphology for use in MAS. Approach 4: We will use a modified pedigree breeding approach to select for resistant breeding lines. Families will be planted in V. dahliae infested and non-infested field experiments. Resistance will be assessed in infested fields. In non-infested fields we will select plants with the superior horticultural characteristics from resistant families for seed production and testing in the next generation.