The influence of RNA-synthesis inhibitors on in vivo pollen tube growth and the self-incompatibility reaction in Lilium longiflorum thunb.

Injection of 3 X 10(-4) g/ml acridine orange, 2 X 10(-5) g/ml actinomycin-D, or 1.34 X 10(-3) g/ml 6-methyl-purine in stigmatic exudate into the hollow styles of Lilium longiflorum immediately before, or 6 or 12 hr after pollination restricted compatible pollen tube growth to lengths typical of incompatible tubes. Treatment 24 hr after pollination resulted either in no effect on compatible tube growth or in a significant retardation of compatible tube growth but not to the length of tubes in incompatibly pollinated styles. Aqueous solutions of these inhibitors at the same concentrations injected into lily styles 6 or 12hr before pollination significantly stimulated incompatible pollen tube growth. These results suggest that RNA synthesis in the style is necessary for the self-incompatibility reaction and RNA synthesis in the pollen tube is required for compatible tube growth. The RNA synthesis in the pollen tube may be completed by 24 hr after pollination.