| Rice,the staple food for over 3.5 billion people in the world,is affected by many diseases and pests.Among them,rice stripe disease(RSD)is a serious threat in Asian countries because of having a history of establishing in the fields and causing repeated outbreaks over the past 50 years.The epidemics of RSD led to 30 – 40% yield losses in the Yangtze River region in China in the early 21 st century.RSD is caused by rice stripe virus(RSV)which is transmitted in a persistent-propagative and transovarial manner by its insect vector,small brown planthopper(SBPH;Laodelphax striatellus).SBPH is not only a polyphagous pest of rice,wheat,oats,maize,and barley but also a vector of some important viruses including RSV.Transmission is an essential step for the infection cycle of viruses and disease epidemic.RSV-SBPH interaction is a complex mechanism as it decides whether the virus was effectively transmitted.This mechanism involves a lot of protein-protein interactions during the virus infection,movement,replication in vector insects.During this study,the interaction of NCP with three SBPH proteins namely sugar transporter 1,sugar transporter 2,and vesicle-associated membrane protein-associated protein B(VAP-B)was verified by yeast two hybrid.Then the m RNA expression level analysis of the three proteins were performed in the insect vector.Further,the interaction between VAP-B of SBPH and RSV NCP was confirmed by pull-down assay.The RNAi for VAP-B was also performed to check its effect on RSV infection and transmission efficiency at different days interval,i.e.2,4,6,8 and 12 days and results verified that the knockdown of VAP-B would lead to RSV reduction in the overall body of SBPH.RNAi of VAP-B was performed to examine the transmission efficiency of subjected SBPHs.The results indicated significantly lower transmission efficiency(10.53 %)after ds RNA injection comparing that of control(GFP ds RNA injection – 44.97 %).The effect of RNAi of VAP-B was maximum in salivary glands after two days,and the m RNA expression of RSV was also minimum in salivary glands in that time.Biological assay indicated a significant decrease in the transmission efficiency of SBPH insects injected by ds RNA of VAP-B.In conclusion,the results suggested that VAP-B of L.striatellus had a strong interaction with the nucleocapsid protein of RSV and might play a significant role in virus transmission.Tomato is the second most important solanaceous vegetable in Pakistan.Interveinal chlorosis and rolling of upper leaves like symptoms of tomato were observed in Multan and Khanewal districts respectively.Surveys were conducted to look for the viruses infecting tomato in these districts.Fifteen samples were collected from Khanewal district and thirty-six samples were collected from Multan district.Reverse transcriptase polymerase chain reaction(RT-PCR)was performed for criniviruses and 27 samples were found to be infected with the tomato chlorosis virus(To CV).Transmission tests plants showed typical To CV symptoms and RTPCR re-confirmed To CV as the causal agent for these symptoms.ELISA was performed to look for the causal agents of upward rolling type symptoms and ten samples were found positive to potato leafroll virus(PLRV).Two isolates of both viruses were selected for partial sequencing and resulted sequences were submitted to NCBI and were assigned with these accession numbers;MN385628 and MN385629(To CV),MN266215 and MN266216(PLRV).To CV and PLRV both were reported first time to infect tomato in Pakistan and this study provides the first sequence-based proof of PLRV infecting tomato in the world. |
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