Another group of secreted proteins
Another group of secreted proteins that determine the virulence of V. dahliae are effectors and microbe associated molecular patterns (MAMP) that regulate plant immunity . So far, there is only one SEA0400 australia gene Ave1 cloned in V. dahliae, yet it does not exist in race 2 strains such as V592 and sequenced VdLs.17 , . The MAMP molecules such as necrosis and ethylene-induced proteins were functionally elucidated , . The representatives are VdNLP1 and VdNLP2 that induced plant cell death and might contribute to pathogen colonization in plants. To figure out the relationship between VdUDG and genes involved in microsclerotial formation as well as pathogenicity, the transcription was quantified for a series of reported genes. As anticipated, genes such as VMK1, VDB, VDH1 and VdGARP1 were significantly downregulated in VdUDG gene knockout mutants. Interestingly, secreted protein genes showed differential expression upon knock-down of VdUDG gene. As it shown in Fig. 8, peVD1 and VdNLP2 were down-regulated, whereas VdNLP1 was strongly up-regulated in VdUDG gene knockout mutants. This is also indicative for the complexity of plant-Verticillium interactions.
Despite the enzyme activity, we have fully investigated the biological function of VdUDG. However, more genes and signal transduction pathways influenced by uracil-DNA glycosylase remain to be investigated. Our study on VdUDG gene would be one case suggesting the importance of epigenetics on plant–pathogen interaction, and hopefully a new way to search for targets of vascular wilt pathogens.
Acknowledgment This work was financially supported by the National Science Foundation granted to FG (31160350 & 31160351), and the China Transgenic Research and Commercialization Key Special Project (2014ZX0800908B). We thank Dr. Chenlei Hua (Institute of Microbiology, CAS) for suggestion to the manuscript.