ISHS Acta Horticulturae 547: III International Symposium on Rose Research and Cultivation
SPREAD OF CROWN GALL DISEASE IN ROSE CULTURES |
| Authors: | C. Poncet, G. Bonnet, S. Pionnat, D. Héricher, A. Bettachini |
| Keywords: | Agrobacterium physiology, plasmids genetics, succinamopine, Polymerase Chain Reaction, Restriction Fragment Length Polymorphism, Mediterranean Region. |
| Abstract:
Crown gall caused by Agrobacterium is one of the most damaging rose diseases, reducing both the vigor of the plants and the yields of marketable flowers. However, our current knowledge of the bacterial strains that invade rose plants and the way they spread is limited. Here, we present the establishment of a collection of 30 Agrobacterium isolates that were obtained from diseased rose plants from France, Spain and Morocco. We also collected information about the origins of plant material that was used for flower production and the culture conditions used for generating the rose plants. Then, the physiological and molecular characteristics of the Agrobacterium isolates were analyzed with determination of the biovar, analysis of the 16S ribosomal DNA (rDNA) restriction fragment length polymorphism (PCR-RFLP), elucidation of the opine-type, and PCR-RFLP analysis of genes involved in virulence and oncogenesis. This study led to the classification of rose isolates into seven groups with common chromosome characteristics and seven groups with common Ti-plasmid characteristics. Furthermore, a strong correlation between plasmid characteristics of the bacterial isolates and the origin of rootstock was found when we analyzed relationship between A. tumefaciens genotypes and the origin of rose plant samples. This study represents the first demonstration that the exponential spread of crown gall disease in Mediterranean rose cultures is due: to the vegetative propagation of rootstocks, to the frequent exchange of plant material between professional breeders, multipliers and grafters, and to the increasing turnover rates for flower production. As an efficient chemical or genetic control of the disease will not be applicable in the near future, a further propagation of disease can be reduced only through selection of healthy rootstocks. Thus, sensitive methods for detection and characterization of the bacteria are required. In our study, we presented valuable tools for such purposes. | |
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