Technical Abstract: The effects of chilling on fruit ripening and the expression of ripening-related genes have been investigated in a wild species introgression breeding tomato line (Solanum lycopersicum ' S. pennelli) that preliminary investigations suggested harbors some fruit chilling tolerance. Fruit were harvested at the breaker stage of ripening were, stored at 3 degrees C for 0, 1, 2 and 4 weeks, followed by 20 degrees C for 0 to 14 d. Fruit stored for 1 week ripened normally as assessed by red color development and softening at 20 degrees C, but those stored for 2 and 4 weeks showed delayed or inhibited ripening. The concentrations of the carotenoids, phytoene, phytofluene, z-carotene, g-carotene and lycopene, but not lutein and beta-carotene, were reduced in chilled fruit. Microarray analysis showed that after storage at 3 degrees C for 4 weeks, 352 genes were up-regulated by chilling, whereas 321 genes were down-regulated, while after 7 d at 20 degrees C, 180 and 126 genes, respectively, were up- and down-regulated in chilled fruit. Chilling-induced changes included expression of transcriptional repressors such as a C2H2-type zinc finger protein and chilling reduced gene expression of a ripening-regulated transcription factor, LeMADS-RIN.