Castor plant is well known to be fairly resistant to biotic stress under the field conditions except for some notorious pests and microbial pathogens.Nevertheless,this condition cannot be taken as a constant phenomenon in castor life cycle since the pathogen-host in interaction in any known biological species is continuous and will selectively generate wavy non-overlapped advantage for one of the two colliding biological systems over an irregular intervals of time and the outcome of which would be co-evolution of both or extinction of either one of the factors.To practically realize this concept, castor plant of wild types have been chosen as a model system in an unusual way after an observation of disease symptoms witnessed in the concerned subjects in Europe.
Scientists from Italy have followed initially an experimental design called “Koch’s Postulates” to confirm that the disease was due to a microbial pathogen and further made extensions in their experimental investigation by molecular probes.They used techniques, PCR and dot blot to precisely detect the nature of pathogen and observed the virulent factor to be a virus. Specifically, the researchers categorized it as Olive Latent Virus 2(OLV2) and found to be a closest relative of type strain OLV 1,infecting tobacco.
Co-evolution of host-pathogen is well noticed in this case following the discovery of a novel viral pathogen in a host what is considered to be resistant.Another interesting aspect is also to be watched with respect to the timely disease observation made by phyto-pathologists on the wild castor plants whose frequency in the natural ecosystem is normally limited.The experimental approach is also relatively robust enough to permit an unambiguous identification of an evolving pathogen.Efforts are still required to better the understand the pathogen behaviour and its transmission media for formulation of effective disease management procedures in agricultural cultivars in a pre-determined way.
For reference: http://www.sipav.org/main/jpp/volumes/0202/020208.pdf