Functional Analysis Of A Putative Bax Inhibitor-1 Homolog In Fusarium Graminearum

Fusarium graminearum is a major pathogen that causes Fusarium head blight on wheat and ear rot on corn.Bax inhibitor-1 is very conserved in animal,plant and yeast.As an ancient inhibitor of cell death,it plays a key role in programmed cell death.To characterize this gene in filamentous fungi,we retrieved the ortholog in F.graminearum by BLASTP search of the Fusarium genome database.Then we knockouted FgBI-1 by homologous recombination.The results showed that loss of FgBI-1 had no effect on its vegetative growth,pigment formation,conidiation,germination rate,sexual reproduction,DON accumulation and pahtogenicity and so on.Consequently,it is believed that BI-1 is not essential during its developmental process since its loss caused no apparent phenotypes.Because of the predicted function involving in apoptosis,we had treated the gene deletion mutant under various stress to see whether it has any difference comparing to the wild-type.Unexpectedly,there is no difference between ?Fgbi-1 and wild-type,though the expression level of FgBI-1 was upregulated when treated by DTT.However,FgBI-1 could partially complement Saccharomyces cerevisiae ?bxilp mutant,and FgBI-1 colocalized with FGSG₀9471 at the endoplasmic reticulum as in yeast,indicating that the BI-1 in Fusarium and yeast may have similar function,which we have not found.