The response of dodder {Cuscuta spp.) seedlings to phytohormones under various light regimes

Summary Phytohormones were screened for their effects on induction of coiling and prehaustoria in de‐etiolated excised dodder seedlings under different light treatments. Zeatin stimulated coiling and the formation of prehaustoria under all light tested, even in darkness. A synergistic effect was observed with zeatin and far‐red light (700–800 nm) but not with red light (600–700 nm) on the formation of prehaustoria. Application of indole‐3acetic acid inhibited zeatin‐induced coiling and prehaustoria development under blue (400–500 nm) and a mixture of red plus far‐red light, but not in blue plus far‐red light. Ethylene had no effect on coiling and prehaustoria development. Observations suggest that zeatin‐induced coiling and prehaustoria development may be mediated by phytochrome.