Project description:Background: Hypovirulent fungal strain Gibellulopsis nigrescens Vn-1 cross-protects sunflower against Verticillium wilt. To discover the mechanism of cross-protection by this hypovirulent strain, we analyzed defense enzyme activities and transcriptomes of root samples infected with virulent and hypovirulent strains. Results: Defense enzyme activities increased after inoculation, with the highest levels observed 24 h post-inoculation. At the same time, defense enzyme gene expressions were upregulated, and H2O2 accumulation decreased. A comparative transcriptome analysis revealed that there are 23 GO terms significantly enriched in the Vn-1 group compared with the control, including three specific oxidoreductase-related and four signaling related GO terms. In addition, there were 7 KEGG pathway only enriched in V33 group compared with the control, and 3 KEGG pathway (Alanine, aspartate and glutamate metabolism, Cutin, suberine and wax biosynthesis and Ribosome) only enriched in Vn-1 compared with the control. Conclusions: According to our results, both hypovirulent strain G. nigrescens Vn-1 and virulent strain V. dahliae V33 can reduce levels of reactive oxygen species in sunflower seedling by regulating HaCAT and HaPOD expression. Twenty three GO terms and three KEGG pathway contribute to the formation of specific resistance against virulent strain V. dahliae V33.
