Genetic challenges of flavor improvement in tomato

In many instances, the intensive breeding of crops over the past half century with a focus on yield has indirectly led to reductions in flavor and nutrient content. Largely, this deterioration of quality relates directly to the genetic and biochemical complexity of such traits. Here, we describe challenges associated with quality improvement, emphasizing tomato fruit flavor. Flavor improvement is particularly problematic because of the difficulty of assessing the phenotype as well as a lack of fundamental knowledge about the chemicals driving consumer preferences, the pathways for their synthesis, and the genes regulating the output of these pathways. Recent breakthroughs from a systematic analysis of these factors and the availability of a tomato genome sequence have led to significant progress in our understanding of flavor. However, the need to deliver improved flavor in the context of high yield and long postharvest shelf life still present major challenges.