Molecular, serological and transmission electron microscopic analysis of the barley yellow dwarf virus-PAVand the cereal yellow dwarf virus-RPV in canary seed (Phalaris canariensisL.)

Abstract

Canary seed (Phalaris canariensis L.) is a cereal crop belonging to the tribe Phalarideae of the Poaceae family. A prevailing virus infection, which causes dwarfing of plants and yellowing of leaves, was observed in canary seed fields in the Tekirdag province of Turkey. The aim of this study was to identify, clone and sequence the cereal viruses naturally occurring on P. canariensis by employing serological tests as DAS-ELISA and TAS-ELISA tests combined with transmission electron microcopy (TEM) and molecular analysis. One hundred and one plant samples showing symptoms were collected and tested serologically using polyclonal antisera against Barley yellow dwarf virus-PAV (BYDV-PAV) and Cereal yellow dwarf virus-RPV (CYDV-RPV). The results of both immunoassays showed that 48% of the samples were infected with BYDV-PAV, 2% with CYDV-RPV and 14% were mixed infection. 36% of the samples were uninfected or infected at level below detection. Aphid transmission experiments revealed that barley (cv. Rubina) exhibited characteristic of CYDV-RPV. Investigations of infected canary grass seedlings using transmission electron microscopy (TEM) supported the findings of serological tests and revealed the presence of isometric particles of approximately 25 nm in diameter. These results were also confirmed by using BYDV-PAV and CYDV-RPV specific primers. Sequence analysis of cDNA and probable translation products revealed a high level of homology to BYDV-PAV and CYDV-RPV isolates found in other plant species. The sequence data obtained from this research were deposited in the EMBL/GenBank Data Libraries under the accession nos. EGO19056 and EF372272.