A genetic approach to improving postharvest quality in lettuce

Ready to eat salad products have considerable added value. However, such products have increased perishability resulting in high wastage. Many leafy vegetables and fruits are susceptible to discolouration, and breeding crop varieties with reduced propensity to discolour offers a cost effective solution as growing them has no added costs. This project facilitates a genetic approach to controlling postharvest discolouration by developing an understanding of the genetics and biochemistry of discolouration and providing underpinning knowledge to allow exploitation of quantitative natural variation in the development of discolouration whilst maintaining other traits (e.g., disease resistance, taste, etc.) at acceptable levels. We have observed that a lettuce (Lactuca sativa) recombinant inbred population from 'Saladin' × 'Iceberg' segregates into two Iceberg and Cos head morphotypes. Levels of phenolics in the leaves are associated with morphotype and processed and bagged leaves from the population show a general negative association between pinking and browning symptoms. Discolouration traits exhibit genotypic variation allowing the identification of breeding material to develop lines with improved postharvest quality. A better understanding of the biochemical variation has the potential to lead to specific treatments that could be applied during processing to reduce discolouration development and increase shelf life