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isolates of Rhizoctonia solani from Camelina sativa (L) CRTZ were differentiated using inoculation and biochemical methods
M. Henneken, 1. Fbiler, V.H. Paul

Universitaet-Gesamthochschule Paderbom, Fachbereich Agrarwirtschaft, Luebecker Ring 2, D 59494 Soest, Germany

Background and objectives
Camelina sativa (L) CRTZ (false flax) is an old culture crop cultivated since about 2000 b.C. Its potential as a renewable oilseed crop was recognized in the 20th century. One major aspect of a modem culture crop is to afford smal argronomic input like disease control, fertilization and soil management. To reach this aim it is required to breed for disease resistance to emerge healthy plants. Further studies [ 1] discovered the production of phytoalexins whitch cause resistance to Aiternaria spp and probably to other diseases, too. Still there are diseases on C. sativa that need to be taken seriously. To breed for disease resisttnce in C. sativa cultivars practical inoculation methods are needed to distinguist between susceptibility of cultivars C. sativa and between different isolates of the corresponding pathogens. In the presented study two infection methods were established to inoculate C. sativa with Rhizoctonia solani. Differentiation of ten C. sativa cultivars and eight isolates of Rhizoctonia solani was carryed out. Additional biochemical investigations to differentiate the isolates of Rhizoctonia solani were carried out.


Materials and Methodes
Eight isolates of Rhizoctonia solani were isolated from field plots of C. sativa at seven locations in Germany and Poland. The first inoculation method was a quick-agar-test system (QATS) to test the susceptibility of C. sativa cultivars to Rhizoctonia solani. Rhizoetonia solani isolates were grown on PDA (Potato Dextrose Agar) for 3 days. Then C. sativa seeds were added to the surface. After germination the susceptibility was assessed (1 not susceptible; 5 high susceptible). For the second inoculation method Rhizoctonia solani was grown on PDA. For 8 days. The fungal cultures were then mixed with substratum (sand 1 peat 1 : 3) and C. sativa was sown into this mixture. Germination occurred in a climatic chamber (stable conditiones). The assessments of disease symptoms were carried out at the 4 -6 leaf stage. The biochemical differentiation of the Rhizoctonia solani isolates was carried out using the usual methods.


Results and conclusions
The available C. sativa cultivars showed no differences in susceptibility to Rhizoctonia solani but there were some differences in the aggressiveness of the isolates of Rhizoctonia - sOmii. The obtained results from biochemical investigations were compared with the results of the 1 develped inoculation methods used. 5 Rhizoctonia solani isolates can similary be differentiated based upon the biochemical and infections methodes used, while the other 3 can not.


References:
[1] Tewari JP, PS Bains, 1 991: Camelina sativa phytoalexins (camelexin and methoxycamelexin) provide resistance against Alternaria brassicae. Canadien Journal of Plant Pathology, Voilume 13, p. 274