Detection And Identification Of The Pathogen Of Pepper Virus Disease In Shandong Province And The Sequences Analysis Of BWYV And CABYV

Pepper is an important vegetable crop,and Shandong province is one of the major pepper production areas in China.In recent years,with the expansion of the scale of pepper cultivation,the pepper virus diseases are also increasing,which lead to reduced yield and loss of pepper quality,and eventually results in economic losses and restrictions for the pepper industry development.The objective of this study is to further identify the types of viruses infecting pepper and the occurrence and distribution of the viruses on pepper in Shandong province.In this study,542 pepper samples collected from seven urban areas(Jining,Weifang,Liaocheng,Tai’an,Yantai,Dezhou and Zibo)in Shandong province,were tested and identified by 14 kinds of virus specific primers using molecular biology technologies.In addition,the genome sequences of Beet western yellows virus(BWYV)and Cucurbit aphid-borne yellows virus(CABYV)were cloned,sequenced and analyzed.The complete genome sequences of the two viruses were aligned with the others virus sequences,and the similarity analysis and phylogenetic analysis of the whole genome nucleotide sequences were carried out.RNA recombination anaylsis was performed on BWYV and CABYV isolates using RDP 4 software.The main findings are as follows:1.In 2016-2017,14 kinds of viruses were detected for 542 sweet pepper samples,five kinds of viruses were detected,which were BWYV,CABYV,Pepper vein yellows virus(PeVYV),Pepper cryptic virus 1(PCV-1)and Pepper cryptic virus 2(PCV-2).The other viruses were not detected in this study,which were Melon aphid-borne yellows virus(MABYV),Tomato spot wilt virus(TSWV),Southern tomato virus(STV),Chilli ring spot virus(ChiRSV),Tomato mottle mosaic virus(ToMMV),Pepo aphid-borne yellows virus(PABYV),Suakwa aphid-borne yellows virus(SABYV),Peanut stunt virus(PSV)and Tomato necrotic stunt virus(ToNStV).In 2016-2017,the detection rate of virus was 63.65%.In 2016,the detection rate of virus was 64.18%,and in 2017,the detection rate of virus was 60.92%.In the detected viruses,the detection rate of PCV-1 was the highest,it was 32.84%.The detection rate of PCV-2,BWYV and PeVYV were 31.73%,31.32%,7.75% respectively.CABYV has the lowest detection rate,was 0.37%.2.Complex infection phenomenon of the virus was existed among 542 samples.The complex infection rate of the virus was 31.30%.There were mainly two and three kinds of viruses complex infection types,in which two viruses were the main type of complex infection,and the complex infection rate was 92.59%.The complex infection rate of the three viruses was 7.41%.3.One of the pepper samples infected with BWYV was selected from Jining and Weifang in 2016 and 2017 respectively for BWYV genome sequences amplification.Four complete genome sequences of BWYV were obtained,the lengths were between 5693-5699 bp.Fouthermore,the whole genome sequence of CABYV was amplified,and the length of complete genome of CABYV was 5684 bp.4.The similarity analysis and phylogenetic analysis of the whole genome nucleotide sequences of BWYV and CABYV were carried out.The results showed that four BWYV Shandong isolates were clustered on a branch,and the phylogenetic relationship of BWYV Shandong isolates are close to Chinese and Korean isolates,were clustered on a branch.The evolution of BWYV had no obvious relationship with the host,but was related to the geographical location.CABYV-LJ3 is related to China,Korea and Japan isolates,and is clustered on a branch.The evolution of the CABYV is mainly related to geographical location and not relevant to the host.Recombination analysis of CABYV and BWYV showed that the recombination phenomenon was occurred between BWYV-JN16311 and BWYV-WF1793 isolates,and CABYV-LJ3 was recombined with Chinese isolate(GQ221223),and potentially recombined with Chinese isolate(HQ439023).