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.

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.

Tomato chlorosis virus (ToCV) is an RNA virus and a member of the Closteroviridae, Crinivirus, that is primarily vectored by Bemisia tabaci MED (B. tabaci MED). An outbreak of ToCV causes destructive damage to tomato plants and other solanaceous vegetables. Currently, ToCV has not been effectively controlled. Rhodopseudomonas palustris PSB-06 is a novel biological agent that is effective at controlling the tobacco mosaic virus (TMV). In this study, we investigated the role of PSB-06 in ToCV-infected tomato plants, and we studied the effects of PSB-06 on plant defense and plant photosynthetic pathways. Furthermore, the effect of PSB-06 on the acquisition and transmission of B. tabaci MED was determined. The results showed that compared with water-treated tomato plants, the contents of jasmonic acid increased, and the activities of catalase, peroxidase and superoxide dismutase increased significantly in tomato plants treated with PSB-06. The relative expression of genes involved in chlorophyll development, chlorophyll metabolism and photosynthesis also increased significantly. Simultaneously, treatment with PSB-06 reduced the acquisition and transmission of B. tabaci MED. We verified the hypothesis that PSB-06 is effective at controlling ToCV by promoting plant defense responses and reducing the amount of ToCV in tomato plants. We also confirmed the ability of B. tabaci MED to transmit ToCV. This study should help to control B. tabaci MED and reduce the spread of ToCV.