Abstract: 【Aim】 Ubiquitination is an important reversible post-translational modification, which is involved in cell cycle, signal transduction, transcriptional regulation and immune response. However, the function of ubiquitin-proteasome system in virus transmission by insect vectors remains unknown. This study aims to explore the interactions between the ubiquitin-proteasome system of whitefly Bemisia tabaci and Tomato yellow leaf curl virus (TYLCV). 【Methods】 The expression levels of ubiquitin and proteasome subunit genes in Bemisia tabaci adults feeding on TYLCV-infected and uninfected tomato plants were detected by RT-qPCR. Changes in the contents of free and conjugated ubiquitin proteins in B. tabaci adults after TYLCV infection were detected by Western blotting. After the ubiquitin-proteasome system was disrupted with specific inhibitors or dsRNA injection, changes in the TYLCV content in B. tabaci adults were detected by RT-qPCR. 【Results】 Carrying TYLCV did not lead to significant change in the expression levels of ubiquitin and 26S proteasome subunit 4, 6B and β genes in B. tabaci adults, and had no influence on the contents of free ubiquitin and conjugated ubiquitin proteins and their ratio, suggesting that TYCLV has no effect on the ubiquitin-proteasome system of the whitefly. However, disrupting ubiquitin-proteasome system by specific inhibitors Bortezomib or MG132 or silencing Rpn11 by RNAi led to significant increase in the TYLCV content in B. tabaci adults. 【Conclusion】 Ubiquitin-proteasome system negatively regulates the TYLCV content in B. tabaci. Ubiquitin-proteasome system might help the whitefly to counteract the negative influence from TYLCV through degrading the virus directly or activating immune response.

Key words: Bemisia tabaci, Begomovirus, Tomato yellow leaf curl virus (TYLCV), virus transmission, ubiquitin, proteasome