Evaluation for Efficient Hairy Root Production Assessed by GFP-gene Expression in Tomato Cultivars Inoculated with Agrobacterium rhizogenes MAFF07-20001

When leaf segments of a tomato cultivar ‘Ponderosa’ were inoculated with Agrobacterium rhizogenes MAFF07-20001 carrying the binary vectors pRi and pBI121/sGFP, adventitious roots were developed from calli formed at the edges of the segments. Primordial roots were obtained with green fluorescence under blue light and elongated vigorously on hormone-free medium without loss of the green fluorescence. They were easily distinguishable from the non-fluorescing roots on the same segments. Successful integration of the sGFP and rol C genes into the chromosome of tomato roots was confirmed by polymerase chain reaction and Southern hybridization. The present method enables us to evaluate the hairy root formation without subculture, isolation and DNA analysis. All commercial cultivars available in Japan (24 cultivars) and 14 breeding lines of tomato were tested by this method. All but two breeding lines produced the hairy roots. Thus, the present method is useful for hairy root production in tomato.