Selection and Evaluation of the Resistant Resources to Rose Crown Gall Disease

Fifty samples of Rosa spp. were inoculated with the highly virulent strain J-5-1 of Agrobacterium tumefaciens as in vivo testing for resistance to crown gall disease in 2003, 2004. According to disease incidence, tumor size and weight and the impacts on the hosts'growth, these materials were categorized as:highly resistant, moderately resistant, moderately susceptible and highly susceptible. R. rugosa,R. xanthina, R. hybrida 'Fire', R. hybrida ' Double Delight', R. hybrida 'Blue Ribbon 'were highly resistant;R. multiflora 'Inermis No3 ', R. multiflora 'Inermis No4', R. multiflora var. cathayensis and R. multiflora 'Baiyutang'and other 13 materials were grouped as moderately resistant. R. multiflora 'Inermis No11 ', R. multiflora f. carnea, R. chinensis, R. hybrida 'Rouge Meilland',R. hybrida 'Goldmarie'and other 12 materials were moderately susceptible. R. x odorata, R. hybrida 'Schloss Mannieim', R. hybrida 'Yankee Doodle', R. hybrida 'Princess de Monaco'and other 7 samples were highly susceptible. Furthermore, in vitro testing method was introduced to escape the limitations of in vivo testing method. It showed that the tumor size produced on the in vitro cultured plantlets was significant different among the samples, and it could be used as an index for the hosts'susceptibility to A. tumefaciens. The result of in vitro testing method was basically consistent with that of in vivo testing method.