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Abstract Seven cDNA clones for ripening‐related mRNAs were used as hybridization probes to study the regulation of gene expression during tomato ( Lycopersicon esculentum 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 poly(A)+ 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 before lycopene synthesis began. Thereafter, the mRNAs increased to maximum levels at the orange stage and then declined slowly as fruit turned red. When mature green fruit were picked before any increase in ethylene synthesis occurred and placed in air plus 10 cm 3 m −3 ethylene, substantial changes in translatable mRNA were noted within 30 h. Five mRNAs that increased in amount directed the synthesis in vitro of polypeptides similar in size to those encoded by the five ripening‐specific clones. Several different patterns of mRNA accumulation were observed, with increases in concentration of the order of 300‐fold.
Maunders et al. (Sun,) studied this question.