FvBCK1, A BCK1Homolog, Is Required For Cell Wall Integrity, Microconidia Development And Pigments Production In Fusarium Verticillioides

FvBCK1was predicted to encode mitogen-activated protein kinase kinase kinase(MAPKKK) in Fusarium verticillioides homologous to BCK1which is the componentof CWI pathway in Saccharomyces cerevisiae. Targeted deletion of FvBCK1resultedin the F. verticillioides growing slowly and showing severe sensitivity tochitin-binding agent Calcofluor White, reducing agent DTT,high temperature and cellwall-degrading enzyme. The FvBCK1deletion mutant only produced microconidialfales heads, but no microconidial chains were detected on modified Bilai's culturemedium. Furthermore, the FvBCK1mutant failed to produce pigments as many aswild type strain. Complementation of the mutated gene restored its tolerance to cellwall-disturbing compounds, ability to produce microconidial chains and pigments.Taken together, our results suggest that FvBCK1is an MAPKKK involved inmaintaining cell wall integrity, micoconidia development, and secondary metabolismof F. verticillioides.