Hydrolyase; part of the gene cluster that mediates the biosynthesis of a tyrosine-derived cytochalasan acting as a fungal signal recognized by resistant rice plants and leads to avirulence in Pi33 resistant rice cultivars (PubMed:18433432). The first step in the pathway is catalyzed by the hybrid PKS-NRPS ACE1, assisted by the enoyl reductase RAP1, that are responsible for fusion of the tyrosine precursor and the polyketide backbone (PubMed:29142718). The polyketide synthase module (PKS) of ACE1 is responsible for the synthesis of the polyketide backbone and the downstream nonribosomal peptide synthetase (NRPS) amidates the carboxyl end of the polyketide with the tyrosine precursor (PubMed:29142718). Because ACE1 lacks a designated enoylreductase (ER) domain, the required activity is provided the enoyl reductase RAP1 (PubMed:29142718). Reduction by the hydrolyase ORFZ, followed by dehydration and intra-molecular Diels-Alder cyclization by the Diels-Alderase ORF3 then yield the required isoindolone-fused macrocycle (Probable). A number of oxidative steps catalyzed by the tailoring enymes identified within the cluster, including cytochrome P450 monooxygenases CYP1 to CYP4, the FAD-linked oxidoreductase OXR2 and the short-chain dehydrogenase/reductase OXR1, are further required to afford the final cytochalasans that confer avirulence and which have still to be identified (Probable). The monooxygenase CYP1 has been shown to be a site-selective C-18 hydroxylase whereas the function of CYP3 is the site-selective epoxidation of the C-6/C-7 olefin that is present in some intermediate compounds (PubMed:31644300). Finally, SYN2 and RAP2 are not required for avirulence in Pi33 resistant rice cultivars (PubMed:18433432). Secondary metabolite biosynthesis. Homodimer. Expressed exclusively during fungal penetration of host leaves, the time point at which plant defense reactions are triggered. Belongs to the AB hydrolase superfamily. FUS2 hydrolase family.