FURTHER EVIDENCE FOR VIROID ETIOLOGY OF APPLE SCAR SKIN AND DAPPLE APPLE DISEASES

Two species of low molecular weight RNA have been associated with apple scar skin and dapple apple diseases.
Both RNAs (ASSARNA 1 and ASSARNA 2) were purified from diseased apples.
Polyacrylamide gel electrophoresis of the purified preparation under denaturing conditions showed that ASSARNA 1 existed in two forms, possibly linear and circular forms.
Under the same electrophoretic conditions ASSARNA 2 migrated faster than the rapidly migrating form of ASSARNA 1. But under fully denaturing conditions (preheated to 100°C for one min.) ASSARNA 2 migrated more slowly than that of ASSARNA 1.

Young seedlings were inoculated with ASSARNA 1 by the razor-slash method.
Thirteen months after inoculation nucleic acid was extracted from the bark of inoculated seedlings and analysed by two cycles of polyacrylamide gel electrophoresis.
ASSARNA 1 was detected in 8 of 14 inoculated seedlings.
The results indicated that ASSARNA 1 was transmitted to apple seedlings and multiplied.

All the properties of ASSARNA 1, so far examined, coincide with those of viroids.
However, the pathogenicity of ASSARNA 1 and the role of ASSARNA 2 are still unknown.

XIII International Symposium on Fruit Tree Virus Diseases

H. Koganezawa

https://doi.org/10.17660/ActaHortic.1986.193.2