Zucchini yellow mosaic virus(ZYMV) was detected by RT-PCR from pumpkin(Cucurbita moschata) plant showing yellowing and mosaic symptom from Liaocheng,Shandong Province.The 3′-termial 1 684 bp genomic sequence covered 633 bp of NIb encoding sequence,840 bp of cp gene and 211 bp of 3′-untranslated region of the isolate ZYMV-Liaocheng was determined.The cp gene of ZYMV-Liaocheng shared identities of 81.4%-98.8% and 89.4%-99.5% at nucleotide and amino acid levels,respectively,with other ZYMV sequences available in the GenBank.Phylogenetic analysis indicated that ZYMV could be clustered to 6 genotypes.ZYMV-Liaocheng belonged to genotype I,which contained isolates from Asia,Europe and America.Genotypes III and V were unique and contained only isolates from East Asia.The isolates from East Asia had the highest variability.
Four isolates of Rice black-streaked dwarf virus(RBSDV)were collected from the maize plants showing rough dwarf symptom in Linyi and Tai’an,Shandong province.The S10 genomic sequences of these isolates were determined and compared with those of 14 other RBSDV isolates.All of the four sequences were 1 801 base pairs(bp)long including the 5’-UTR of 21 bp and the 3’-UTR of 103 bp.They all contained an open reading frame of 1 677 bp(22-1698),encoding the coat protein(CP)of 558 amino acids.The sequences of these four RBSDV isolates and those of the major cp gene of 14 other isolates available in the GenBank were divided into two groups in the phylogenetic tree.Recombination analysis indicated that the isolate Lym2 was likely a recombinant of isolates Lym1 and Zhjs.
Chaste tree(Vitex negundo var.heterophylla)witches’-broom was a new disease found in Mountain Taishan and the neighboring region.Phytoplasmal cells could be easily observed in the phloem sieve elements of diseased plants under electron microscope.The 16S rRNA gene of phytoplasma associated with this disease(CTWB)was amplified with nested-PCR with the universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2.An amplified fragment of ca.1.2 kb was sequenced and subjected to identity and phylogenetic analyses.Phytoplasma CTWB shared identities of more than 99.0% with members of Aster yellows group(16SrI)in 16S rRNA genes.It had the highest identity of 99.8% with phytoplasmas associated with Maize bushy stunt(subgroup 16SrI-B),and clustered into a common branch with phytoplasmas of the subgroup in the phylogenetic tree constructed with 16S rRNA genes.These results indicated that CTWB belonged to subgroup B of Candidatus Phytoplasma asteris(16SrI-B).
