Loop-mediated isothermal amplification (LAMP) for rapid detection of Rhodococcus fascians on ornamentals

Virulent strains of Rhodococcus fascians (Rf) have the potential to cause fasciation, leafy gall (Fig. 1a) and shoot proliferation (Fig. 1b) in susceptible host plants by interfering with the plant’s hormone balance (2). This gram-positive bacterium (Fig. 1c) is of increasing concern to ornamental growers due to its wide host range and the lack of effective control methods. The only sure option for growers is to destroy infected plants. However, it is almost impossible to determine whether a plant intended for propagation is infected until it is too late and the next generation plants are showing symptoms. Current detection methods, including polymerase chain reaction (PCR), are expensive and not readily transferable to growers. Loop-mediated isothermal amplification (LAMP) has been successfully applied to the detection of numerous microbial pathogens (3). The LAMP reaction uses 4 to 6 primers, each with sequence complementary to a selected region of pathogen DNA (Fig. 2). Maryna Serdani, M. Curtis and M. L. Putnam Department of Botany and Plant Pathology Oregon State University, Corvallis, OR 97331