Isolation and nucleotide sequence analysis of a partial cDNA clone for potato Y-VN (Korean isolate) genome

Abstract

Potato Virus Y-VN (PVY-VN) isolated from Nicotiana tabacum var. 'Burley 21’ in Korea was verified by electron microscopy observations of purified virions and SDS-PAGE analysis of viral proteins. RNA was isolated from the purified PVY particles and about 10 pg of RNA was obtained from approximately 500 pg of particles. Double strand cDNA was synthesized by using oligo(dT) primer and cloned in a Smal site of pUC19. The size of cDNA inserts was estimated by restriction enzyme digestion analyses. The identification of coat protein gene of PVY-VN was done by Southern blot analysis using a radiolabeled 900 bp fragment of PVY (isolate Amigo) as a probe. The insert of the longest cDNA clone 18 was subcloned into pUC19 and subjected to sequencing analysis. The nucleotide sequences of the clone 18 reported here comprise the entire viral coat protein gene and almost the full length of the nuclear inclusion protein b (Nib) gene region, totalling 2,541 nucleotides in length. The PVY-VN coat protein (CP) starts at Gi^s and codes for 267 amino acids with A/r=30,062. At the amino acid level the CP sequence of PVY-VN strain shares a 93 to 96% sequence homology with those of PVY strains whose CP sequences are known.