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

• Published in: Journal of plant pathology 2009-07, Vol.91 (2), p.500-500
• Main Authors: Yue, H.N., Sun, R.H., Wei, T., Wu, Y.F.
• Format: Article
• Language: English
• Subjects: Disease Note; DNA; Phytoplasma; Plant diseases; Prunus; Prunus armeniaca
• ISSN: 1125-4653; 2239-7264

In July 2007, a phytoplasma-like disease was observed on apricot plants (Prunus armeniaca L.) grown in the Chinese province of Shaanxi. Affected trees were stunted and showed yellow, small and upward curled leaves. Incidence of this disease was less than 15%. From samples collected from 14 symptomatic and six symptomless plants in six different orchards, total DNA was extracted from ca. 0.5 g of leaf midrib or stem phloem tissue using a modified cetyltrimethyl-ammonium bromide (CTAB) method (Qi et al., 2004). DNA extracts were analyzed by nested PCR, using the 16S rRNA gene universal primer pairs R16mF2/R16mRl followed by R16F2n/R16R2 (Gundersen et al., 1996), which amplified a 1.4 kb and a 1.2 kb product, respectively, from symptomatic plants only. RFLP analysis of the 1.2 kb products with AluI, MseI, HhaI, HpaI, RsaI, BfaI, HinfI and TaqI endonudease (Lee et al., 1998), showed that all symptomatic plants were infected by a phytoplasma belonging to the subgroup B of the elm yellows group (16SrV-B) (Candidatus Phytoplasma ziaphi). The nucleotide sequence of cloned 16SrDNA (Gen-Bank Accession No. FJ572660) showed the highest identity (99%) with comparable sequences of subgroup 16SrV-B, thereby confirming the results of RFLP analysis. Phytoplasmas of 16SrV-B subclade have previously been detected in cherry in China and in peach in India (Lee et al., 2004), and in Poland in apricot imported from China (Cieslinska et al., 2004). However, to our knowledge, this is the first molecular evidence of the presence of a phytoplasma of the 16SrV-B subgroup associated with a leafroll-type disease of apricot in northern China.