Identification And Evolution Analysis Of Soybean Mosaic Virus From Wild Soybeans (Glycine Soja) In China

Soybean mosaic virus(SMV)is the major virus disease worldwide in soybean,resulting in substantial yield losses and significant seed quality deterioration.At present,the investigation of the SMVs is mainly carried out in cultivated soybeans(Glycine max),but the study on species and genetic diversity of SMVs in wild soybeans(Glycine soja)is not enough,especially in China.In this study,a total of 60 wild soybean samples collected in 2013 from northeastern and southern China were examined for seed-borne viruses.The results showed that 12 of the samples developed typical mosaic,shrinkage and other symptoms.RT-PCR and sequencing were performed by designing two pairs of Potyvirus primers(PVYG-FI/R1 and PVYG-F2/R2).These 12 samples were infected by SMV,and were grouped into nine types,of which seven were further sequenced.The seven new SMV genomic sequences were then compiled with 83 known SMV genomic sequences to build a phylogenetic tree.It was shown that the four SMVs isolated from the southern wild soybeans all belong to clade II and are similar to the known isolates SC7,BYX006 and LJZ002,all of which contain a recombinant bean common mosaic virus(BCMV)fragment(?900 bp)at the upstream part of the genome.The three northeastern SMV isolates were found to be distributed in clade III and clade IV.Overall,this work revealed that wild soybeans in China also act as important SMV hosts and play a role in the transmission and diversity of SMVs.The southern and northern SMV isolates(SC7-N and HLJBADS001)were used to infect the offspring of representative individuals in wild soybeans.The results showed that 33 samples were resistant to HLJBADS001 and SC7-N,and 26 samples were resistant to HLJBADS001.Therefore,wild soybeans are rich in anti-SMV resources.