First Report of Sweet potato leaf curl virus on Blue Morning Glory in Greece.

Abstract

Blue morning glory (Ipomoea indica, Convolvulaceae) plants are widespread along the Greek coast, where they grow as weeds in addition to being cultivated as ornamentals. Yellow vein symptoms are frequently observed on these plants. These symptoms are similar to those reported for isolates of Sweet potato leaf curl virus (SPLCV) infecting I. indica in Italy and Spain (1,3). SPLCV belongs to the sweepoviruses, a unique group within the genus Begomovirus in the family Geniminiviridae that infects sweet potato (I. batatas) crops around the world. In May 2013, three leaf samples of I. indica showing yellow vein symptoms were collected in Kolymbari (Crete Island), where ~50% of the observed plants were symptomatic, and five asymptomatic leaf samples were collected in Kremasti and Mandriko (Rhodes Island). Total DNA, isolated from all samples, was used as a template in rolling-circle amplification (RCA) using ϕ29 DNA polymerase (TempliPhi kit, GE Healthcare, Little Chalfont, UK) and the product was digested with a set of restriction endonucleases. The samples from Kolymbari and one sample from Kremasti yielded amplification products that were shown to contain a single BamHI site. The DNA fragments of ~2.8 kbp obtained from one sample from each island were cloned into pBluescript II SK(+) (Stratagene, La Jolla, CA). Inserts of two clones from the Kolymbari sample and one clone from the Kremasti sample were completely sequenced (Macrogen, Seoul, South Korea). Sequences were aligned with available sequences of sweepoviruses using MUSCLE and pairwise identity scores were calculated with SDT as described (4). The sequences obtained from Kolymbari (2,830 nt, GenBank Accession Nos. KF697069 and KF697070) were 98.8% similar between them and showed the highest nucleotide identity (97.7%) with a SPLCV isolate obtained from an I. indica plant in Sicily Island (Italy) (AJ586885) (1). The sequence obtained from Kremasti (2,804 nt, KF697071) showed the highest nucleotide identity (92.4%) with a SPLCV isolate (previously named as Ipomoea yellow vein virus, which is currently a synonym of SPLCV [2]) obtained from an I. indica plant from southern Spain (EU839578) (3). Nucleotide sequence identities were above the 91% threshold for begomovirus species demarcation (2), thus confirming that the begomoviruses found infecting I. indica in Greece are isolates of SPLCV. It is worth to note that the infected I. indica plant from Kremasti did not show any conspicuous symptoms, thus highlighting the importance of this species as an alternative host for SPLCV, which could thus affect the sweet potato crop that is grown in Greece in familiar plots. To our knowledge, this is the first report of SPLCV in Greece.