Improving Stress Tolerance in Carrots

A Popular Vegetable Crop Faces Unique Threats

Carrot production in the United States is under threat from both climate and biological dangers. Because most carrots are irrigated, limited access to water is a major risk factor for carrot producers in Southern California, where 83% of carrots are grown, and this risk has increased in the last century.

Additionally, carrots are susceptible to destructive diseases. Alternaria leaf blight (Alternaria) is one of the most dangerous diseases affecting carrots and can reduce yields by 40-60%. Some cultivated carrots are partially resistant to Alternaria but still require frequent fungicide applications to fully protect crops.

A University of California, Davis, research team led by Dr. Allen Van Deynze, director, UC Davis Seed Biotechnology Center and associate director, UC Davis Plant Breeding Center, in collaboration with Dr. Phil Simon, research leader at the U.S. Department of Agriculture (USDA) Agriculture Research Service, is investigating wild carrots that have shown resistance to Alternaria or can be grown in water-deficient conditions. After determining which wild carrots succeed, researchers will breed them with cultivated carrots to develop these traits in commercial carrots. The investigators are also studying the genetic basis of disease and water-deficiency tolerance to help strengthen these traits in future generations of carrots and other root crops.

Wild Carrots Can Provide Genetic Solutions

Wild carrots (Daucus carota) have rich genetic resources that protect them from drought, disease and other stresses; however, these genetic resources have been bred out of many cultivated carrots. This project employs a multifaceted approach to breed tolerance to water deficiency and Alternaria into cultivated carrots. The research team is exposing wild varieties to water-deficient conditions and Alternaria to determine which have elevated stress tolerances and studying the successful carrots’ genetics to better understand how to improve the traits conferring tolerance. The wild carrots are sourced from the USDA National Plant Germplasm System.

The researchers plan to provide major seed companies and crop breeders with breeding germplasm – genetic material – derived from wild carrots determined to have the best potential to pass on desired traits, along with breeding methods and tools. These partners will in turn deliver resistant carrots to growers. This research is quickly developing carrot crops that both prevent yield and economic loss for growers and ensure the supply of carrots and carrot-based products for consumers.