Molecular Characterization of the 3′‐Terminal Region ofTurnip mosaic virusIsolates from Eastern China

Abstract

Turnip mosaic virus (TuMV; genus Potyvirus, family Potyviridae) causes great losses to cruciferous crop production worldwide. The 3¢-terminal genomic sequences of eight TuMV isolates from eastern China were compared with those of 74 other Chinese TuMV isolates of known host origin in the GenBank and isolated during the past 25 years. The reported sequences of the eight TuMV isolates are 1125 or 1126-nucleotides (nt) long excluding the poly(A) tail. They all contain one partial open reading frame of 912 nt, encoding 304 amino acids, followed by a stop codon and a non-translated region of 209-210 nt. Results of phylogenetic analyses showed that Chinese TuMV isolates clustered into three groups: basal-BR, Asian-BR and world-B. The ratios of non-synonymous and synonymous substitutions and results of amino acid alignment provided evidence for purifying or negative selection in TuMV populations of China. *Tian Y.-P. and Zhu X.-P. contributed equally to this research.www.blackwell-synergy.com

Complete genomic sequence analyses of Turnip mosaic virus basal-BR isolates from China

“…Our previous results had shown that, according to the CP genes, Chinese TuMV isolates were under negative or purifying selection [21]. In this research, we confirmed that conclusion according to analyses of the whole ORF and other genes, and further proved that the selection pressure on P1, the most diverse part in potyviral genome, was the highest.…”

“…The results showed that, as the case for CP genes [21], the d NS / d S ratios for other genes were close to 0, which implied that negative or purifying selection on Chinese TuMV isolates. The d NS /d S ratios for genes P1 and P3 were higher than those for other genes, implying that the selection pressure on these two genes was higher.…”

“…They were in a state of sudden expansion and had evolved into more and more sub-lineages [17,18]. Isolates belonging to basal-BR group in China were first collected in the year 2004-2005 [21]. The genetic structure of Chinese TuMV population was being studied in our laboratory to elucidate the incidence and state of different sublineages, especially those on recently discovered sublineage basal-BR.…”

“…The conserved amino acids FDSS [46] at position 2611-2614 of the polyprotein was located 266 aa upstream of the putative NIb/CP cleavage site. The conserved (S/T)G-(X) 3 -T(X) 3 -N(S/T)(X) [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] GDD that is necessary for RNA polymerase activity and NTP binding began at position 2669. In CP, the DAG motif that interacts with PTK of HC-Pro to regulate virus transmission by aphids [47] was located at position 2882-2884.…”

“…However, our previous research indicated that basal-BR isolates did occur in China [21]. In this article, we determined the full-length genomic sequences of the first two basal-BR isolates from China, and analyzed the recombination pattern and genetic diversity of Chinese TuMV isolates.…”