Detection and Characterization of Abscission-Inhibiting Substances in Leaves of Malformin-Treated Cuttings

Malformin, which induces resistance to dark leaf abscissionfollowing treatment in the light, did not alter the course ofdark aging (loss of chlorophyll, wet and dry weight) in Vigna.Peroxydisulfate, which destroys IAA, did not influence malformininducedabscission resistance. Leaf blades from cuttings treated withmalformin in the light contained higher levels of abscissioninhibitors, which could be divided into ethanolsoluble and water-solublefractions. The inhibitors appeared to be heat stable anionsthat are insoluble in ether. Although malformin also increasedthe amount of abscission inhibitors in leaves when applied inthe dark, where malformin stimulates abscission, a parallelincrease in abscission stimulators may explain the failure ofthese inhibitors to function in the dark. (Received June 25, 1984; Accepted August 20, 1984)