An R2R3-MYB transcription factor, SlMYB28, involved in the regulation of TYLCV infection in tomato

Tomato yellow leaf curl virus (TYLCV), which is one of the most critical plant diseases, is transmitted by Bemisia tabaci. TYLCV is a devastating disease of tomato, seriously affecting the growth of infected tomato plants. MYB transcription factors play central roles in plant development and pathogen defense response, but their functions in tomato defense response to TYLCV infection remain incompletely understood. In this study, a tomato MYB gene, SlMYB28 was identified. The open reading frame of SlMYB28 gene spans 702 bp, encoding 233 amino acids. SlMYB28 is an R2R3-MYB transcription factor. Nuclear localization assays revealed that SlMYB28 protein localizes to the nucleus. In the promoter region of SlMYB28 gene, a few cis-elements related to plant development or environmental stress responses were observed. SlMYB28 expression was strongly induced by TYLCV infection in TYLCV-susceptible cultivar 'Jinpeng-1'and TYLCV-resistant cultivar 'Zheza-301'. We further investigated the function of SlMYB28 in response to TYLCV by using virus-induced gene silencing. DNA content of TYLCV in SlMYB28-silenced tomato plant was lower than that of the negative control line. These results imply the involvement of SlMYB28 as a negative regulator in regulation of TYLCV infection in tomato.