Messenger RNA Changes in Tomato Fruit Pericarp in Response to Propylene, Wounding or Ripening

Abstract

Summary Immature green tomato ( Lycopersicon esculentum Mill. Line 83G38) fruits were treated with propylene for 2, 4 or 6 days. The respiration rates of the propylene-treated fruit were higher than those of untreated fruit but fell when the propylene was withdrawn. Fruit exposed to propylene for 4 or more days had a higher percentage of polysomes than had untreated fruit or fruit treated for only 2 days. RNA was recovered from individual fruit, translated in a wheat germ translation system in the presence of 35 S-methionine and the products separated by gel electrophoresis and examined by fluorography. Two polypeptide products that were prominent in translations of ripening but not green fruit were seen in all normal fruits examined immediately after exposure to propylene for 2, 4 or 6 days. In fruits exposed to propylene for 2 days but returned to air for 4 days before the RNA was extracted, the ripening-related products were either not seen or were not prominent. Shifts in messenger RNA populations in response to propylene treatments were the same in the ripening-inhibited mutant rin as in the normal line but were reduced in the nonripening nor mutant line. It is concluded that the induction of the messenger RNAs for these ripening-related polypeptides is not of itself sufficient to induce ripening. Wounding either mature-green or ripe pericarp tissue induced a characteristic set of translatable messenger RNAs within 2 hours. One of the set was translated in vitro to a product of Mr 37,500 daltons. This product was also prominent in translations of the RNA of unwounded ripe fruit but was much less prominent with unwounded green fruit. It was not induced when immature fruit was given propylene treatments which did not induce ripening. It is concluded that, apart from the RNA for the 37,500 dalton product, wounding and ripening provoke distinct populations of messenger RNAs.