Factors influencing root formation in dicots by Agrobacterium rhizogenes

Abstract

Agrobacterium rhizogenes (Riker et al.) Conn genetically transforms the roots of many dicotyledonous plants, causing them to produce numerous functional secondary roots. The intentional inoculation of forest, nursery, or vegetable transplants with A. rhizogenes may have some value in promoting rapid establishment after transplanting. We examined some factors that may influence the development of roots in plants inoculated with A. rhizogenes (by the carrot disc assay). A pH near neutrality, a temperature of ca. 25 °C, and a freshly cut root surface serving as the inoculation site favoured root development. Roots that were inoculated and then stored at 10 °C did not produce secondary roots at that temperature. However, upon placement at 23 °C for 2 days new roots began to form. Octopine at 10 mM stimulated root production. Carrot roots stored for 9 months produced few if any roots upon inoculation with A. rhizogenes, suggesting the importance of tissue age in genetic transformation.