Acetohydroxyacid synthase FgIlv2 and FgIlv6 are involved in BCAA biosynthesis, mycelial and conidial morphogenesis, and full virulence in Fusarium graminearum

作者：Liu Xin; Han Qi; Xu Jianhong; Wang Jian; Shi Jianrong^*

来源：Scientific Reports, 2015, 5(1): 16315.

DOI：10.1038/srep16315

In this study, we characterized FgIlv2 and FgIlv6, the catalytic and regulatory subunits of acetohydroxyacid synthase (AHAS) from the important wheat head scab fungus Fusarium graminearum. AHAS catalyzes the first common step in the parallel pathways toward branched-chain amino acids (BCAAs: isoleucine, leucine, valine) and is the inhibitory target of several commercialized herbicides. Both FgILV2 and FgILV6 deletion mutants were BCAA-auxotrophic and showed reduced aerial hyphal growth and red pigmentation when cultured on PDA plates. Conidial formation was completely blocked in the FgILV2 deletion mutant Delta FgIlv2-4 and significantly reduced in the FgILV6 deletion mutant Delta FgIlv6-12. The auxotrophs of Delta FgIlv2-4 and Delta FgIlv6-12 could be restored by exogenous addition of BCAAs but relied on the designated nitrogen source the medium contained. Deletion of FgILV2 or FgILV6 also leads to hypersensitivity to various cellular stresses and reduced deoxynivalenol production. Delta FgIlv2-4 lost virulence completely on flowering wheat heads, whereas Delta FgIlv6-12 could cause scab symptoms in the inoculated spikelet but lost its aggressiveness. Taken together, our study implies the potential value of antifungals targeting both FgIlv2 and FgIlv6 in F. graminearum.

• 出版日期2015-11-10
• 单位江苏省农业科学院