Functional Analysis of the Pyruvate Carboxylase Gene in Fusarium oxysporum f. sp. Momordicae
Bitter gourd wilt is a soil-borne vascular disease caused by Fusarium oxysporum f. sp. Momordicae (FOM). Fusaric acid (FA), a fungal toxin, plays an important role during host infection by Fusarium. Pyruvate carboxylase (PC), a key enzyme in the tricarboxylic acid cycle, has important functions in fungal energy metabolism, amino acid biosynthesis, and pathogenicity. In this study, a gene encoding pyruvate carboxylase, FoPycA, was identified in FOM. A FoPycA deletion construct was generated using the split-marker strategy, and the knockout mutant and complemented strain were obtained by polyethylene glycol (PEG)-mediated protoplast transformation. In addition, the expression levels of genes related to fusaric acid biosynthesis in the mutant were analyzed by RT-qPCR. The results showed that deletion of FoPycA significantly increased the sensitivity of the strain to cell membrane- and cell wall-damaging stresses, reduced the expression levels of genes involved in fusaric acid biosynthesis, and markedly attenuated pathogenicity. In conclusion, FoPycA is involved in fusaric acid biosynthesis in FOM and thereby affects its stress tolerance and pathogenicity