Evaluation Of Crown Gall Disease Resistance In Hybrids Of Rosa 'Pekcougel' And Tetraploid Of R. Multiflora 'Matsushima No. 3'

Crown gall disease caused by Agrobacterium tumefaciens causes economic loss in ornamental production in Japan. To breed a resistant rootstock, we used crown gall resistant Rosa 'PEKcougel' to hybridized with tetraploid of R. multifora 'Matsushima No. 3'. In this study, we investigated the crown gall resistance characteristics in their progenies. In the needle prick test, eight tested progenies showed significantly smaller wounds than R. 'PEKcougel'. In the stem segment culture and opine assay, six progenies formed no callus tissue while three progenies formed calluses and had no opine detected. Further oncogene expression analysis was performed to evaluate crown gall disease resistance, since the low callus formation rate limited the application of opine assay. In the oncogene expression analysis, some progenies of tetraploid of R. multiflora 'Matsushima No. 3' showed a lower expression level of both 10 and iaaM than R. 'PEKcougel'. Furthermore, ipt expression had a significant positive relationship with tumor size. Taken together, these results suggest that ipt expression analysis can be used for evaluating crown gall disease resistance in rose progenies. Furthermore, eight progenies with strong crown gall disease resistance were confirmed.