Gene expression during the ripening of tomato fruit was investigated by cDNA cloning and hybrid-select translation. A cDNA library was prepared from poly(A)-containing mRNA from ripe tomato fruit and sreened by differential hybridization. 146 ripening-related cDNA clones were found. Eleven groups and eight unique clones have been identified so far. The sizes of the cloned cDNA inserts were determined and type-members for seven groups were used in hybrid selection experiments. Six of the seven clones encode translation products corresponding to six ripening related polypeptides detected previously by in vitro translation of total cytoplasmic RNA (14). One cDNA group codes for a Mr 48 000 protein that was identified as polygalacturonase on the basis of immunoprecipitation with specific antiserum raised against tomato polygalacturonase. re]19840918 rv]19850613 ac]19850618.

Seven cDNA clones for ripening-related mRNAs were used as hybridization probes to study the regulation of gene expression during tomato {Lyeopersieon eseulentum Mill) ripening. The mRNAs corresponding to each clone were detected by Northern blotting and the sizes of the transcripts compared with the molecular weights of polypeptides identified previously by hybrid-release translation. Dot hybridization to poIy(A)-t-mRNA from leaves, roots, unripe and ripe tomatoes established that five of the clones encoded mRNAs that were ripening specific and two encoded mRNAs also expressed in other organs. Appearance of these ripening-specific mRNAs was correlated with ethylene production as ripening commenced and occurred befote lycopene synthesis began. Thereafter, the mRNAs increased to maximum levels at the orange stage and then declined slowly as fruit turned red. When tnature green fruit were picked before any increase in ethylene synthesis occurred and placed in air plus 10 cm-* m^-* ethylene, substantial changes in translatable tnRNA were noted within 30 h. Five mRNAs that increased in amount directed the synthesis in vitro of poiypeptides similar in size to those encoded by the five ripening-specific clones. Several different patterns of mRNA accumulation were observed, with increases in concentration ofthe order of 300-fold.

No abstract

Seven cDNA clones for ripening-related mRNAs were used as hybridization probes to study the regulation of gene expression during tomato {Lyeopersieon eseulentum Mill) ripening. The mRNAs corresponding to each clone were detected by Northern blotting and the sizes of the transcripts compared with the molecular weights of polypeptides identified previously by hybrid-release translation. Dot hybridization to poIy(A)-t-mRNA from leaves, roots, unripe and ripe tomatoes established that five of the clones encoded mRNAs that were ripening specific and two encoded mRNAs also expressed in other organs. Appearance of these ripening-specific mRNAs was correlated with ethylene production as ripening commenced and occurred befote lycopene synthesis began. Thereafter, the mRNAs increased to maximum levels at the orange stage and then declined slowly as fruit turned red. When tnature green fruit were picked before any increase in ethylene synthesis occurred and placed in air plus 10 cm-* m^-* ethylene, substantial changes in translatable tnRNA were noted within 30 h. Five mRNAs that increased in amount directed the synthesis in vitro of poiypeptides similar in size to those encoded by the five ripening-specific clones. Several different patterns of mRNA accumulation were observed, with increases in concentration ofthe order of 300-fold.

No abstract