Praxelis clematidea is a very vigorous non-native weed in tropical and subtropical regions of China. P. clematidea plants showing symptoms of phyllody disease were found in an orchard located in Hainan province, PR China. The presence of phytoplasmas was confirmed by PCR of 16S rRNA gene using phytoplasma universal primers R16mF2/R16mR1 followed by R16F2n/R16R2. According to 16S rRNA gene sequence similarity, the P. clematidea phyllody (PCP) phytoplasma is a 'Candidatus Phytoplasma australasiae'-related strain (99.5 % similarity). The virtual RFLP pattern analyses of 16S rRNA gene sequences indicated that the PCP is a new subgroup within 16 Sr group II. The most similar RFLP pattern is the reference pattern of 16Sr group II, subgroup M, with a similarity coefficient of 0.94. These results were confirmed by phylogenetic analyses of the 16S rRNA gene. These findings suggest that P. clematidea phyllody disease is caused by a new phytoplasma considered to be a novel subgroup, 16SrII-V.

Rubber tree (Hevea brasiliensis Muell. Arg.), a tropical perennial crop species which produces natural rubber widely used in industries, is the most important economic crop in tropical areas of China. Rubber trees exhibiting symptoms of stem fasciation; irregular bending of branches, witches’ broom, little leaves on abnormal branches and early withering of abnormal branches (Figure 1) were observed during a field survey conducted in December 2011 in Hainan Province, China. The disease was named rubber tree stem fasciation (RTSF). The incidence rate of RTSF is less than 3% in surveyed areas. Former studies have reported similar symptoms associated with phytoplasmas in rubber tree on the basis of transmission electron microscope (Chen et al. 1991). The objectives of this work were to detect and identify the agent associated with the symptomatic rubber trees and to carry out molecular characterization of the pathogen. Samples of symptomatic (21) and asymptomatic (6) rubber trees were collected in three locat...

The complete genomic sequence of a Cassava common mosaic virus Linggao isolate (CsCMV-LG) was determined from cassava (Manihot esculenta Crantz) with mild leafy mosaic symptom to no symptom in China. Excluding the poly(A) tail, the CsCMV-LG genome (GenBank accession No. MT038420) is 6374 nucleotides (nts) in length, with five major open reading frames encoding a 1450-amino acids (aa) RNA-dependent RNA polymerase (RdRp), three triple gene block (TGB) proteins (231-aa, 110-aa and 95-aa), and a 229-aa coat protein (CP). Phylogenetic analysis indicated that the complete genome of the CsCMV-LG is closely related to that of CsCMV-Brazilian which has been assigned to the genus Potexvirus, but the sequence identity shared only 88.0%. Notable, the mild CsCMV-LG isolate can also infect Nicotiana benthamiana in laboratory through rub inoculation causing mild vein yellowing at 15-day post inoculation. This is the first full-length genome sequence of a distinct isolate of Cassava common mosaic virus (CsCMV) infecting cassava in Hainan, China.