USE OF AN IN VIVO INFECTIOUS CDNA CLONE OF STRAWBERRY MILD YELLOW EDGE POTEXVIRUS TO STUDY THE ETIOLOGY OF THE DISEASE

A potexvirus that is transmitted in a persistent manner by the strawberry aphid Chaetosiphon fragaefolii has been associated with strawberry mild yellow edge disease.
To study the etiology of the disease and its vector transmission, a full-length in vivo infectious cDNA clone of the potexvirus (SMYEPV) was constructed by ligating together cDNA fragments of the MY-18 isolate.
The cDNA was inserted between the cauliflower mosaic virus 35S promoter and a polyadenylation signal.
To enable the production of constructs of other virus isolates, a method to generate full-length PCR products was developed.
Mechanical inoculation of the MY-18 full-length construct resulted in local infections on Chenopodium quinoa and C. foetidum. Fragaria vesca ‘Alpine’ seedlings were systemically infected after biolistic or agroinoculation with the construct.
The plants developed symptoms that were indistinguishable from control plants inoculated by graft or aphid transmission.
Infections were evaluated by TAS-ELISA and immuno-electron microscopy (IEM). The presence of SMYEPV particles was confirmed by decoration using an antiserum (no. 648) to a chimeric coat protein expressed in Escherichia coli. The potexvirus was not aphid transmissible from strawberry inoculated with the MY-18 full-length construct, thus suggesting that a helper mechanism is required for vector transmission.
The nucleotide sequence of the 3′ terminal half of the D-74 isolate, encompassing the triple gene block and the coat protein, was obtained and compared with the MY-18 isolate.

VIII International Symposium Small Fruit Virus Diseases

S. Lamprecht, W. Jelkmann

https://doi.org/10.17660/ActaHortic.1998.471.5