Callus and cell suspension cultures of Rudgea jasminoides, a tropical woody Rubiaceae

Abstract

Rudgea jasminoides is a woody Rubiaceae that produces phytoalexins in response to fungal inoculation, the response being dependent of the seasonal conditions. With the aim of studying phytoalexin induction under controlled conditions, callus cultures were established from petiole explants of R. jasminoides on a modified basal MS medium supplemented with picloram alone or in combination with kinetin. The highest frequency of callus formation was observed in solid medium containing 2.22 μM kinetin and 2.07 μM picloram. Development of fast-growing friable white callus was achieved in the absence of kinetin, in cultures supplemented only with 8.28 μM picloram. Cell suspension cultures were established from this friable callus by transferring pieces directly to the same medium without agar. Preliminary experiments revealed that cell suspension cultures of R. jasminoides represent a useful system to analyse induced defensive metabolites produced by this Rubiaceae species.