Characterisation of Hop stunt viroid (HSVd) isolates from jujube trees (Ziziphus jujuba)

Abstract

Hop stunt viroid (HSVd) has been detected in many woody species including grapevine, citrus, peach, plum, apricot, and almond. Here, we report the first detection of HSVd in jujube trees (Ziziphus jujuba). Ninety-five samples were collected from jujube trees in Cangzhou, Baoding, and Handan of the Hebei province of China in June 2006. An additional 70 samples were collected from Taigu, the Shanxi province of China in August 2008. From these samples, low molecular weight RNAs were extracted for two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), hybridisation, and reverse transcription polymerase chain reaction (RT-PCR) assays. HSVd was detected in three of the 165 samples, giving an infection rate of 1.8%. The sequences of the HSVd isolates from jujube trees shared 92.6–92.8% homology with the first reported HSVd sequence (GenBank: X00009). Using alignment and phylogenetic analyses, the HSVd sequence variants from jujube were classified in the plum subgroup and were found to be more conserved than other HSVd subgroups.