Mapping Fruit Susceptibility to Postharvest Physiological Disorders and Decay Using a Collection of Near-isogenic Lines of Melon

Melon (Cucumis melo L.) is a perishable fruit that requires refrigeration to extend its shelf life. Postharvest behavior differs substantially among melon varieties due to genetic differences. In this work, we use a collection of near-isogenic lines (NILs) derived from a cross between the Spanish cultivar Piel de Sapo (PS) and an exotic Korean accession 'Shongwan Charmi' SC (PI161375), each of them with a single introgressed region from SC into the PS background, to detect and map quantitative trait loci (QTLs) involved in postharvest life traits, such as total losses, water-soaking, necrosis of the placental tissue, chilling injury (CI), decay, fruit over-ripening, flesh browning, hollow flesh disorder, and flavor loss during storage. Fruit were examined at harvest and after 35 days at 8 degrees C. Three QTLs induced desirable quality traits: flv4.1 reduced the loss of fruit flavor after refrigeration, tl8.1 reduced total losses, and fus8.4 reduced the susceptibility to fusarium rot (Fusarium Link). Another 11 QTLs produced a detrimental effect on other quality traits. The NIL population was useful for dissecting complex, difficult-to-measure pre- and postharvest disorder traits of different degrees of development and for investigating flavor loss during storage. Further studies with the QTLs described herein will shed light on the genetic control of melon shelf life and help breeders who are interested in this fruit quality trait.