First report of grapevine viroids in the East Mediterranean region of Turkey

Grapevine (Vitis vinifera L.) is one of the most important crops in Turkey, with a total area under production of 540,000 hectares producing 3,400,000 tons of grapes (Anon., 2000). The East Mediterranean region of Turkey has 19.7% of the grapevine growing areas of the country and the varieties Tarsus Beyazý, Yalova Ýncisi, Antep Karasý, Hatun Parmaðý, Ergin Çekirdeksiz, Perlette and Cardinal are the most important.

Viroids are widespread throughout all grapevine growing areas of the world. According to sequence analysis 6 distinct viroids have been recognised on grapevine (Szychowski et al., 1988). A survey was conducted during 1999-2001 to identify viroids affecting grapevine in the East Mediterranean region. A total of 184 samples of the major grapevine varieties were collected from an area of 135 hectares. Vein banding, yellow vein, leaf rolling, yellowing, spotting and small leaf symptoms were detected in all areas surveyed. The samples were tested for the presence of grapevine viroids by sPAGE and RT-PCR. The viroids were detected by sPAGE essentially as described by Szychowski et al., (1988) following nucleic acid extraction. RT-PCR detection was carried out according to Visvader & Symons (1985).

Sixty-two of the 184 samples were found to be infected using sPAGE analysis. These samples were then tested by RT-PCR (Fig. 1) and 23 were found to be infected with GYSVd-1 (Grapevine yellow speckle viroid-1), 4 with GYSVd-2 (Grapevine yellow speckle viroid-2) and 11 infected with HSVd-g (Hop stunt viroid-grapevine). Seven samples were infected with GYSVd-1 and GYSVd-2, 7 with GYSVd-1 and HSVd-g and 6 with GYSVd-1, GYSVd-2 and HSVd-g. Four samples were infected with CEVd-g (Citrus exocortis viroid-grapevine), GYSVd-1, GYSVd-2 and HSVd-g.

This is the first report of CEVd-g in Turkey, and of GYSVd-1, GYSVd-2 and HSVd-g in the East Mediterranean region.