Developing New Crop Varieties with Enhanced Traits and Disease Resistance
ARS advances multiple crop industries by developing new crop varieties with disease resistance and other trait enhancements and providing new tools and approaches that will support future breeding efforts. In addition to supporting major commodities, ARS breeding programs advance specialty crops, which alone have a U.S. farm gate value of $87.7 billion. The following accomplishments are examples of ARS advances in crop breeding for disease resistance and trait enhancement that were made in FY 2020.
Identification of romaine lettuces with reduced browning discoloration for fresh-cut processing. Lettuce is one of the most valuable fresh vegetables and one of the top 10 most valuable crops in the United States, with an annual farm-gate value of more than $2.5 billion. Fresh-cut lettuce is the primary ingredient of the increasingly popular packaged, ready-to-eat salads; however, discoloration (browning) represents a major challenge that limits its quality and shelf life. Processors who lack effective browning control methods are relying on modified atmosphere packaging (MAP) to achieve low oxygen atmospheric conditions and maintain the shelf life. ARS researchers in Salinas, CA, and Beltsville, MD, identified lettuces with limited browning that will be used in breeding programs and to help identify genes associated with limited browning. These findings are of great benefit to the U.S vegetable industry.
Unlocking the genetic resistance of soft winter wheat preharvest sprouting (PHS). PHS is the germination of wheat grains in the field before harvest following 2 or more consecutive days of rain with cool temperatures. These weather conditions occur in the soft winter wheat growing region about once every 2 years and farmers can lose approximately 30 percent of their crop value, which translates into approximately $420 million annually in the United States. Much is known about the biochemical process of PHS but little is understood about the genetics of PHS. Because its genetic nature is not well understood, few markers exist for breeders to use in developing resistant lines. ARS scientists in Wooster, OH, completed a survey of PHS resistance in a population of nearly 200 diverse soft wheat breeding lines over 3 years and over 2 years in a second, and a more diverse population of older varieties. Nine soft winter wheat varieties were identified as PHS-tolerant over multiple years under PHS-inducing conditions. These findings provide important information for breeders about varieties with tolerance to PHS and the potential for future breeding of PHS resistance.
Potato postharvest quality evaluations and release of new potato cultivars. Acceptable processing quality after storage is an essential attribute of a successful potato variety. The standardized evaluation procedures developed and used by ARS scientists in East Grand Forks, MN, a worksite of the ARS research unit in Fargo, ND, have been an important component of the overall process for evaluation and release of new cultivars by Federal and State cooperators nationwide. In the past year, in support of Federal and non-Federal public breeding/screening programs, 139 advanced breeding lines were analyzed for storage/processing quality at multiple storage temperatures and durations. Since 2015, 17 chip clones and 14 fry processing clones identified in East Grand Forks to have superior storage quality have advanced through rigorous national variety testing platforms aimed at providing potato industry stakeholders a high-quality processed potato product throughout storage. Data from these analyses have contributed to the national release of new potato varieties with superior processing quality throughout storage.
Evaluation of blueberry genetic resources identifies fruit fly resistance. Spotted wing drosophila fruit fly appeared in the United States in 2009 and now causes more than $511 million in damage annually to fruit production in Western states. ARS scientists from Corvallis, OR, and Poplarville, MS, searched blueberry genetic resources for resistance to that fruit fly. Twenty-nine blueberry species were tested with a bioassay for resistance to feeding by the fruit fly larvae and adults. Ten blueberry species were resistant to feeding by the fruit fly; three of those species are indigenous to East Asia, in the fruit fly’s native range. Blueberry species from Central and South America were also resistant. Most highbush blueberry cultivars were susceptible, but rabbiteye and other blueberry cultivars with smaller, firmer fruit types were resistant. These findings will enable blueberry breeders to identify parental lines to cross and produce new blueberry cultivars resistant to this fruit fly.