Location: Crop Improvement and Protection Research
Project Number: 2038-21530-003-031-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Apr 1, 2026
End Date: Mar 31, 2027
Objective:
To characterize mutant lettuce lines derived from cv. ‘Eruption’ for enhanced horticultural performance and disease resistance. The project specifically focuses on developing green-pigmented lines that integrate robust Impatiens necrotic spot virus (INSV) resistance with delayed bolting and superior postharvest quality.
Approach:
Field evaluation and phenotyping mutant lines, alongside ‘Eruption’ and other check cultivars, will be evaluated using standard commercial practices. Trials will follow established, peer-reviewed protocols to ensure data reproducibility. At least two distinct field experiments will be conducted:
Inoculated Trials: Plants will be grown in fields inoculated with Sclerotinia minor sclerotia to rigorously evaluate resistance to lettuce drop.
Uninoculated Trials: These plots will assess performance under natural disease pressure (e.g., downy mildew and INSV) and quantify horticultural traits, including maturity, size, color, and pigment content.
Controlled Environment INSV Screening To mitigate the risk of low natural disease pressure in the field, lines will be screened for INSV resistance under greenhouse conditions. Using the protocol developed by USDA-ARS, which demonstrates high correlation with field observations, we will ensure consistent resistance data regardless of seasonal fluctuations in vector activity.
Laboratory and Molecular Marker Analysis Tissue samples will undergo molecular marker assays to characterize alleles associated with critical traits. Specifically, we will screen for resistance to:
Verticillium wilt (Race 1)
Corky root
Lettuce Mosaic Virus (LMV)
Tomato Bushy Stunt Virus (TBSV)
Postharvest shelf-life longevity.
Molecular marker data will be validated against established resistance profiles to confirm genetic potential.