Carrot (Daucus carota) is an important US vegetable crop that has an annual value of $820 million (USDA NASS 2016). Sclerotinia sclerotiorum is a devastating necrotrophic pathogen that affects >400 plant species in the field and in storage. S. sclerotiorum alone accounts for up to 50% of carrot post-harvest losses. Although multigenic (QTL)-mediated partial resistance has been discovered in specific cultivars of some crop species, no complete resistance to S. sclerotiorum has yet been identified. The capacity of plants to produce antibiotic compounds is one important pathogen defense mechanism.

Carrots and other Apiaceous species produce polyacetylenic lipids, often in the form of falcarins such as falcarinol and falcarindiol, C₁₇ aliphatic compounds with multiple triple bonds thought to be derived from linoleic acid (C_18:2). These falcarins are known to have potent antibiotic activities against human pathogens as well as anticancer activities. Although they have been described in primary literature for decades, their role in plant disease resistance and the genetic basis of their biosynthesis remain poorly understood. Results on the biosynthesis and functional role of falcarins in defense against S. sclerotiorum and other necrotrophic pathogens will be presented.