Phytoparasitica (1997) 25, p. 85 (Saenger et al.)

H.L. Sänger, J. Henkel and R. Spieker (1997)
RNA-recombination between two parental viroids is still taking place in individual coleus plants today and generates a novel viroid offspring
Phytoparasitica 25 (1), 85-85
The Xth International Congress of Virology, August 11-16, 1996, Jerusalem, Israel, lecture
Abstract: In various Coleus blumei cultivars three new viroids were found, which are named CbVd 1, CbVd 2 and CbVd 3 and whose prototypes are 250, 302 and 362 nucleotides long, respectively. They all contain an identical central region (CR) but its sequence differs strikingly from the CRs of all other presently known viroids. Except for their CR, CbVd 1 and CbVd 3 are completely unrelated, whereas CbVd 2 is a recombinant viroid that arises by fusion of the right-hand part and the CR of CbVd 1 with the left-hand part of CbVd 3. The distribution pattern of these three viroids in two sets of 50 individual plants propagated from a single mother plant, respectively, by cuttings, was analyzed over a period of 4 years. At the beginning, CbVd 1 was present in all plants, ca 90% of which contained CbVd 3, 20% harbored CbVd 2, and in 13% of the plants only CbVd 1 and CbVd 2 were found. This pattern changed during the following years of culture but finally still 100% of the plants contained CbVd 1 whereas 65% carried the recombinant CbVd 2. However, in 50% of the latter plants CbVd 3 had been evidently defeated by the novel CbVd 2 offspring. Thus the Coleus viroid system is a naturally occurring viroid family which represents a kind of missing link in support of the repeatedly proposed RNA recombination as an important factor in viroid evolution.

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Coleus blumei viroids