3.3 AaFla1 mediates the anti-tumour activity of A. alstroemeria
To further investigate the molecular mechanisms underlying the loss of antitumour activity of AaLaeA OE26, the results of the metabolomic analysis were combined and found that flavonoids (epicatechin gallate) might contribute prominently to the antitumor activity of AaLaeA OE26. Therefore, we hypothesized that AaLaeA primarily regulated flavonoid synthesis inAaLaeA OE26. And then, we did an in-depth analysis of metabolomic and transcriptomic data, and a total of 86 genes involved in flavonoid metabolism and antitumour related were obtained (Table S2). The gene number 3698 encoding FAD-binding domain protein (Fla1) (Fig.4A) was mostly significantly down-regulated inAaLaeA OE26. The expression of this gene inAaLaeA OE26 was verified using qRT-PCR and found to be consistent with the results of transcriptome analysis (Fig. 4B). To confirm whether Fla1 mediates the antitumour activity of the fungus,Fla1 was overexpressed in A. alstroemeria wild type (Fig. S3). It was found that overexpression of Fla1 led to a significant increment in the antitumour activity of the strain. The IC50 of AaFla1 OE23 against A549 was 368 μg/mL, significantly lower than that of WT at 445 μg/mL (Fig. 4C); The rate of apoptosis was also significantly increased (Fig. S4), about 4.72-fold higher than WT (Fig. 4D). Those suggest that Fla1 mediates the antitumour activity of A. alstroemeria .