Factors Influencing Induction of Resistance to Dark Abscission by Malformin

摘要

Factors influencing induction of resistance to dark abscission by malformin on cuttings ofVigna radiataduring treatment in light were examined. When light duration (13.5 W m−2) increased from 0 to 48 h, the effect of malformin on subsequent dark abscission changed from stimulation only (0 to 4 h), stimulation followed by inhibition (8 to 12 h), to inhibition only (24 to 48 h). Maximum abscission resistance occurred after 48 h when irradiance was 6.6 W m−2. Kinetin treatment in light reduced subsequent dark abscission by controls but did not reduce abscission on malformintreated cuttings. Hadacidin had no effect on induction of abscission resistance by malformin. IAA, hydroxyproline, CaCl2, sucrose, and NH4NO3were inactive. ABA and ethephon completely blocked induction of abscission resistance by malformin. Inhibition of abscission induced by kinetin was also blocked by ABA. Because both puromycin and malformin inhibited dark abscission following treatment in light, malformin may induce abscission resistance by inhibiting protein synthesis or promoting formation of other substances which inhibit protein synthesis. Leaf blade removal from the distal end of the petioles abolished malformin-induced abscission resistance. It is suggested that in light malformin induces formation of abscission-inhibiting compounds in leaves which are responsible for development of abscission resista