In vitro testing of rose rootstocks resistance to crown gall disease

Abstract

Fifteen rose rootstocks which were cultured and propagated in vitro were inoculated with the strain GOU1 of Agrobacterium tumefaciens as a test for resistance to the crown gall disease. Rosa multiflora and R. multiflora 'K2' were highly susceptible, 95% and 90% of the stems forming large tumors, 6.61 and 3.62 (mm x mm), respectively. Three varieties of R. canina, 'Pfander', 'Superbe', and 'Brogs Stachellose', and a native one became infected but formed small tumors (0.5 mm x mm). In R. rugosa and R. canina 'Superbe' 40% of the infected shoots formed tumors during the first week after inoculation. Thus, these species have a low resistance to tumor formation, whereas R. virginiana formed no tumor during the first week after inoculation; 73% of the shoots produced tumors 3 weeks after inoculation. Therefore, R. virginiana is subject to infection but resistant to tumor formation.