Co-infection of TYLCV and ToCV increases cathepsin B and promotes ToCV transmission by Bemisia tabaci MED.

Tomato disease is an important disease affecting agricultural production, and the combined infection of tomato chlorosis virus (ToCV) and tomato yellow leaf curl virus (TYLCV) has gradually expanded in recent years, but no effective control method has been developed to date. Both viruses are transmitted by Bemisia tabaci Mediteranean (MED). Previously, we found that after B. tabaci MED was fed on ToCV-and TYLCV-infected plants, the transmission efficiency of ToCV was significantly higher than that on plants infected only with ToCV. Therefore, we hypothesize that co-infection could enhance the transmission rates of the virus. In this study, transcriptome sequencing was performed to compare the changes of related transcription factors in B. tabaci MED co-infected with ToCV and TYLCV and infected only with ToCV. Hence, transmission experiments were carried out using B. tabaci MED to clarify the role of cathepsin in virus transmission. The gene expression level and enzyme activity of cathepsin B (Cath B) in B. tabaci MED co-infected with ToCV and TYLCV increased compared with those under ToCV infection alone. After the decrease in cathepsin activity in B. tabaci MED or cathepsin B was silenced, its ability to acquire and transmit ToCV was significantly reduced. We verified the hypothesis that the relative expression of cathepsin B was reduced, which helped reduce ToCV transmission by B. tabaci MED. Therefore, it was speculated that cathepsin has profound research significance in the control of B. tabaci MED and the spread of viral diseases.

Integrated Analysis of microRNA and mRNA Transcriptome Reveals the Molecular Mechanism of Solanum lycopersicum Response to Bemisia tabaci and Tomato chlorosis virus.

Tomato chlorosis virus (ToCV), is one of the most devastating cultivated tomato viruses, seriously threatened the growth of crops worldwide. As the vector of ToCV, the whitefly Bemisia tabaci Mediterranean (MED) is mainly responsible for the rapid spread of ToCV. The current understanding of tomato plant responses to this virus and B. tabaci is very limited. To understand the molecular mechanism of the interaction between tomato, ToCV and B. tabaci, we adopted a next-generation sequencing approach to decipher miRNAs and mRNAs that are differentially expressed under the infection of B. tabaci and ToCV in tomato plants. Our data revealed that 6199 mRNAs were significantly regulated, and the differentially expressed genes were most significantly associated with the plant-pathogen interaction, the MAPK signaling pathway, the glyoxylate, and the carbon fixation in photosynthetic organisms and photosynthesis related proteins. Concomitantly, 242 differentially expressed miRNAs were detected, including novel putative miRNAs. Sly-miR159, sly-miR9471b-3p, and sly-miR162 were the most expressed miRNAs in each sample compare to control group. Moreover, we compared the similarities and differences of gene expression in tomato plant caused by infection or co-infection of B. tabaci and ToCV. Taken together, the analysis reported in this article lays a solid foundation for further research on the interaction between tomato, ToCV and B. tabaci, and provide evidence for the identification of potential key genes that influences virus transmission in tomato plants.

Aphid endosymbiont facilitates virus transmission by modulating the volatile profile of host plants.

BACKGROUND: Most plant viruses rely on vectors for their transmission and spread. One of the outstanding biological questions concerning the vector-pathogen-symbiont multi-trophic interactions is the potential involvement of vector symbionts in the virus transmission process. Here, we used a multi-factorial system containing a non-persistent plant virus, cucumber mosaic virus (CMV), its primary vector, green peach aphid, Myzus persicae, and the obligate endosymbiont, Buchnera aphidicola to explore this uncharted territory. RESULTS: Based on our preliminary research, we hypothesized that aphid endosymbiont B. aphidicola can facilitate CMV transmission by modulating plant volatile profiles. Gene expression analyses demonstrated that CMV infection reduced B. aphidicola abundance in M. persicae, in which lower abundance of B. aphidicola was associated with a preference shift in aphids from infected to healthy plants. Volatile profile analyses confirmed that feeding by aphids with lower B. aphidicola titers reduced the production of attractants, while increased the emission of deterrents. As a result, M. persicae changed their feeding preference from infected to healthy plants. CONCLUSIONS: We conclude that CMV infection reduces the B. aphidicola abundance in M. persicae. When viruliferous aphids feed on host plants, dynamic changes in obligate symbionts lead to a shift in plant volatiles from attraction to avoidance, thereby switching insect vector's feeding preference from infected to healthy plants.

Silencing of Odorant-Binding Protein Gene OBP3 Using RNA Interference Reduced Virus Transmission of Tomato Chlorosis Virus.

Tomato chlorosis virus (ToCV) is widespread, seriously impacting tomato production throughout the world. ToCV is semi-persistently transmitted by Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Currently, insect olfaction is being studied to develop novel pest control technologies to effectively control B. tabaci and whitefly-borne virus diseases. Despite current research efforts, no report has been published on the role of odorant-binding proteins (OBPs) in insect preference under the influence of plant virus. Our previous research showed that viruliferous B. tabaci preferred healthy plants at 48 h after virus acquisition. In this study, we determined the effect of OBPs on the host preference interactions of ToCV and whiteflies. Our results show that with the increase in acquisition time, the OBP gene expressions changed differently, and the OBP3 gene expression showed a trend of first rising and then falling, and reached the maximum at 48 h. These results indicate that OBP3 may participate in the host preference of viruliferous whiteflies to healthy plants. When the expression of the OBP3 gene was knocked down by an RNA interference (RNAi) technique, viruliferous Mediterranean (MED) showed no preference and the ToCV transmission rate was reduced by 83.3%. We conclude that OBP3 is involved in the detection of plant volatiles by viruliferous MED. Our results provide a theoretical basis and technical support for clarifying the transmission mechanism of ToCV by B. tabaci and could provide new avenues for controlling this plant virus and its vectors.

[Effects of Rhodopseudomonas palustris PSB06 on Pepper Rhizosphere Microbial Community Structure].

The use of biological pesticide can greatly reduce the soil pollution in the environment. Exploring the effect of biological pesticide on community diversity and distribution of pathogenic bacteria will provide theoretic basis for subsequent researches on biological pesticide micro-ecological control. In order to explore the microbial ecological mechanism of pepper phytophthora blight, this research compared the difference of microbial diversity between rhizosphere soil of infected and healthy plants, and the effects of Rhodopseudomonas palustris PSB06 on microbial diversities of plant rhizosphere soil were investigated using Illumina MiSeq sequencing technology. The results showed that there was less difference in the microbial diversity from the same soil between the seventh day and the fourteenth day. The microbial diversity of rhizosphere soil of healthy plants was higher than that of rhizosphere soil of infected plants. The soil sprayed with Rhodopseudomonas palustris PSB06 exhibited the highest diversity. Moreover, the abundance of Actinomycetes in the rhizosphere soil of healthy plants was higher than that of infected plants, and the highest abundance of Actinomycetes was observed in the soil sprayed with Rhodopseudomonas palustris PSB06. The microbial diversity between rhizosphere soil of infected and healthy plants was significantly different. Spraying Rhodopseudomonas palustris PSB06 could significantly alter the microbial community structure of the soil. It could also increase the diversity of microorganism and the abundance of Actinomycetes in the soil.

Development of a lateral-flow assay (LFA) for rapid detection of Soybean mosaic virus.

Soybean mosaic virus (SMV) is the most common virus in soybean and poses a serious threat to crop production and germplasm recession in many countries worldwide. In this study, a highly practical and rapid lateral-flow assay (LFA) was developed for the detection of SMV. The SMV coat protein (CP) was prokaryotically expressed and purified to immunize mice. After generation of hybridoma cell lines, four anti-SMV monoclonal antibodies were selected. The LFA-strip was then assembled using a double-antibody sandwich strategy. When the SMV-infected leaf sample was assayed using the assembled LFA-strip, the positive pink color appeared in the test line within 5-10min. The strip only gave positive results with SMV and not other viruses tested and could be used to detect 800 fold dilutions of infected leaf samples. The LFA could be used to detect SMV in infected leaf tissue as well as soybean seeds. To our knowledge, this is the first report of the development of a LFA for the detection of SMV. The practical, rapid and specific assay that was developed in this study can be widely applied to the diagnosis and surveillance of SMV in the laboratory and the field.

One-step reverse transcription loop-mediated isothermal amplification for the rapid detection of cucumber green mottle mosaic virus.

Cucumber green mottle mosaic virus (CGMMV) has caused serious damage to Cucurbitaceae crops worldwide. The virus is considered one of the most serious Cucurbitaceae quarantine causes in many countries. In this study, a highly efficient and practical one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) was developed for the detection of CGMMV. The total RNA or crude RNA extracted from watermelon plants or seeds could be detected easily by this RT-LAMP assay. The RT-LAMP assay was conducted in isothermal (63°C) conditions within 1h. The amplified products of CGMMV could be detected as ladder-like bands using agarose gel electrophoresis or visualized in-tube under UV light with the addition of a fluorescent dye. The RT-LAMP amplification was specific to CGMMV, as no cross-reaction was observed with other viruses. The RT-LAMP assay was 100-fold more sensitive than that of reverse-transcription polymerase chain reaction (RT-PCR). This is the first report of the application of the RT-LAMP assay to detect CGMMV. The sensitive, specific and rapid RT-LAMP assay developed in this study can be applied widely in laboratories, the field and quarantine surveillance of CGMMV.