Molecular characterization and phylogenetic analysis of hop stunt viroid isolates from sweet cherry in China

Hop stunt viroid (HSVd), a member of the family Pospiviroidae , infects a large number of plants and causes substantial economic losses. In this study, HSVd was detected in dappled fruits of sweet cherry and then molecularly characterized. We sequenced 164 cDNA clones from six sweet cherry cultivars in the Shandong Province of China and identified 23 HSVd sequence variants, which ranged in size between 293 and 303 nucleotides (nt) and shared 97~99% sequence identity with each other. Characterization of HSVd variants revealed that three were predominant in sweet cherry trees. Phylogenetic analysis showed that most of the HSVd variants isolated from sweet cherry were clustered within the plum-type group and that two variants were clustered with the recombinant P-C group, regardless of geographic origin. This study identified 23 HSVd variants and provided the molecular characterization of viroid infection (HSVd) in sweet cherry in China.