Stimulation of ethylene production by a cell wall component from mature green tomato fruit

Pectic (carbonate‐soluble, covalently‐bound pectin, CBP) material stimulated increased ethylene production when vacuum‐infiltrated into whole, mature green tomato (Lycopersicon esculentum Mill. cv. Rutgers) fruit. Activity was greatest if CBP was extracted from mature green tomatoes with jellied locules. CBP extracted from mature green tomatoes with immature seeds had no elicitor activity, while CBP from turning or red ripe tomatoes was only moderately active. Infiltration of CBP from normal mature green fruit into ripening inhibitor (rin) mutant tomato fruit stimulated ethylene production and attenuated red pigmentation in these fruits. Partial purification of the active material was accomplished using DEAE‐Sephadex and BioGel P‐100 chromatography. The most highly purified fraction is comprised of neutral carbohydrate (95%) with a relatively low content of amino acids (1%) and a uronic acid content of less than 5%. This material may be an endogenous trigger of ethylene production and ripening.