Estimation of hyperauxinity during tumour formation in castor bean hypocotyls

The hyperauxinity of tumourous tissues of castor bean plants(Ricinus communis L. variety Pacific 6), infected by Agrobacteriumtumefaciens (Smith and Town) Conn, strain B6, was quantitativelyestimated. The auxin extracted was found to be indole-aceticacid (IAA), which gave a typical Ehrlich's reaction, an equalR.f. value and a characteristic indole UV spectrum which weresimilar to those of authentic IAA. The Avena coleoptile straightgrowth test revealed a higher auxin concentration in the typicalR.f. region (0.2–0.4) in the tumourous tissues than inthe control. Colorimetric estimation of the auxin concentrationin developing tumourous tissues revealed fluctuating hyperauxinitiesthroughout the test period. The possible nature of this fluctuationis discussed but it is still unexplained. (Received January 28, 1975; )