Genetic background of quality and cell wall changes in fresh-cut melons

Fresh-cut melon is a growing and convenient segment of melon products. Melon cultivars were not bred specifically for fresh-cut processing, and the genetic bases for fresh-cut quality are unknown. We examined the link between fresh-cut quality, cell wall changes, and genetics in three near-isogenic lines (NILs) of melon (Cucumis melo L.) and in a 'Piel de Sapo' (PS) cultivar during a 9-day storage period at 4°C. The three NILs differed in initial firmness and differences persisted throughout storage of fresh-cut melon. Juice efflux was negatively correlated with flesh firmness. The climacteric NIL SC3-5-1 was softer and had higher juice efflux than the remaining NILs of the parental line PS. Fresh-cut prepared from NILs SC7-2 and SC10-2 were firmer and generally released less juice than SC3-5-1 and PS. Chelator-soluble pectins of SC3-5-1 exhibited a marked molecular size downshift during a 6-day storage period in SC3-5-1, but no significant differences in molecular size distribution were observed in the other NILs. Apparently two different quantitative trait loci (QTL) with pleiotropic effect were affecting flesh firmness and juice efflux. One QTL located in the linkage group (LG) III increased pectin depolymerisation, which was probably associated with climacteric behavior. Another two QTLs in LG VII and X were associated with initial firmness levels.