Isolates of Turnip mosaic virus (TuMV) are divided into four molecular lineages based on host range and geographical origins. Basal-BR is one of the four lineages and represented a new emergent lineage in East Asia. In one previous paper, we report the occurrence of basal-BR isolates in China. Here, we presented the first two complete genomic sequences of Chinese TuMV basal-BR isolates, WFLB06 and TANX2. The genomes of both isolates were 9833 nucleotides excluding the poly(A) tail, and had identical genomic structure. Most of their genes shared the highest identities with Japanese isolates. Recombination analysis showed that WFLB06 was an interlineage recombinant of basal-BR and Asian-BR parents, while TANX2 was an intralineage recombinant of basal-BR parents, and these two isolates represented two novel recombination patterns of TuMV. The ratio of nonsynonymous and synonymous substitution for the P1 gene of Chinese TuMV population was the highest and amounted to 12 times higher than that for the NIa-Pro gene, which implies that the selection pressure on the P1 gene was the highest among the genes present in the genome.

Elm samples with and without witchesÕ-broom symptoms (EWB) were collected from TaiÕan and Zhaoyuan, Shandong Province, China. Phytoplasmal cells were observed in the phloem cells of symptomatic plants under electron microscope. Specific fragments of about 1.2 kb in length were amplified with nested-PCR from symptomatic samples, while no fragment was obtained from healthy plants. The 16S rRNA gene sequences of the phytoplasmas associated with elm witchesÕ-broom in TaiÕan (EWB-TA) and Zhaoyuan (EWB-ZHY) had high similarities, and formed a sublineage in phylogenetic tree, with members of subgroup B or D of aster yellows group (16SrI). Computer simulated restriction fragment length polymorphism analysis of 16S rRNA gene revealed that EWB-TA and EWB-ZHY patterns had similarity coefficients of 1.00 with the pattern from the representative strains of subgroup 16SrI-B, and had a similarity coefficient of lower than 0.97 with representatives of other subgroups. These results indicated that the phytoplasma strain associated with elm witchesÕ-broom in China was very closely related to ÔCandidatus Phytoplasma asterisÕ OAY, belonging to subgroup-B of aster yellows group (16SrI-B). This is the first report of a phytoplasma associated with elm witchesÕ-broom disease in China.

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