Mechanism of parasitism by Cuscuta reflexa: Distribution of cytokinins in different regions of the parasite vine

Cytokinins in the different regions of Cuscuta reflexa Roxb. vine have been extracted and assayed using the Xanthium cotyledon bioassay with N6‐benzylaminopurine as the reference cytokinin. Maximum cytokinin level was found in the haustoria‐bearing region with the gradient decreasing towards the apex. The cytokinin content of the apex was less than 1% of that in the whole haustorial region. Interestingly, the concave half of the vine contained about forty times more cytokinin in the haustorial region than the corresponding convex half. The high concentration of cytokinin or cytokinin‐like substances in the haustoria‐bearing site in Cuscuta might be due either to a high RNase activity in the region or translocation from the host to parasite or both.