GENES FROM LYCOPERSICON CHMIELEWSKII AFFECTING TOMATO QUALITY DURING FRUIT RIPENING

Three chromosomal segments from the wild tomato, L. chmielewskii, intr ogressed into the L. esculentum genome have been previously mapped to the middle and terminal regions of chromosome 7 (7M, 7T respectively), and to the terminal region of chromosome 10 (10T). The present study was designed to investigate the physiological mechanisms controlled by the 7M and 7T segments on tomato soluble solids (SS) and pH, and thei r genetic regulation during fruit development. The effects of 7M and 7 T were studied in 64 BC2F5 backcross inbred lines (BILs) developed fro m a cross between LA1501 (an L. esculentum line containing the 7M and 7T fragments from L. chmielewskii), and VF145B-7879 (a processing cult ivar). BILs were classified into four homozygous genotypes with respec t to the introgressed segments based on RFLP analysis, and evaluated f or fruit chemical characteristics at different harvest stages. Gene(s) in the 7M fragment reduce fruit water uptake during ripening increasi ng pH, sugars, and SS concentration. Gene(s) in the 7T fragment were f ound to be associated with higher mature green fruit starch concentrat ion and red ripe fruit weight. Comparisons between tomatoes ripened on or off the vine suggest that the physiological mechanisms influenced by the L. chmielewskii alleles are dependent on the translocation of p hotosynthates and water during fruit ripening.