FIRST REPORT OF A 16 SrV-B GROUP PHYTOPLASMA ASSOCIATED WITH A LEAFROLL-TYPE DISEASE OF APRICOTS IN NORTHERN CHINA

Citrus leprosis virus C (CiLV-C), the causal agent of one of the main virus disease of citrus in Brazil, is considered to have a narrow host range. However, recent studies have shown that some weeds, hedgerow and windbreak plants can host CiLV-C, thus may play a role in the epidemiology of the disease (Bastianel et al., 2006). We now report that CiLV-C can infect Glycosmis pentaphylla Retz. DC., a rutaceous shrub native to tropical Asia. G. pentaphylla is grown for its edible ripe fruits in gardens that can be near citrus groves. G. pentaphylla leaves were infested with presumably viruliferous Brevipalpus phoenicis mites, the vector of CiLV-C, which had been reared on leprosisinfected plants for 72 h. Twenty-four days after infestation, localized symptoms appeared as conspicuous dark spots, with a darker center and irregular borders surrounded by a small chlorotic halo. These spots differed significantly from the well-defined chlorotic to necrotic lesions often seen in leprotic Citrus spp. tissues. The symptoms remained unchanged for 110 days. CiLV-C was detected in symptomatic leaves by RT-PCR using specific primers that amplify a region of its putative movement protein gene (Locali et al., 2003). Amplified products had the expected 344 bp size. Thirty-three amplicons were cloned and sequenced (GenBank accession No. EU257507). Their deduced amino acid sequence was 93% identical to that of a Brazilian isolate of CiLV-C (YP_654542.1), confirming the identification of the virus transmitted. This is the first report of CiLV-C infecting a remote citroid fruit tree, and G. pentaphylla is the only so far known CiLV-C host exhibiting such particular symptoms.