Short chain dehydrogenase; part of the SOR gene cluster that mediates the biosynthesis of sorbicillinoids, a diverse group of yellow secondary metabolites that restrict growth of competing pathogenic fungi but not of bacteria (PubMed:29104566). Sorbicillinoids biosynthesis requires the action of two PKSs (PubMed:28809958). The SOR cluster is required for the production of trichodimerol and dihydrotrichotetronin, with sor2 being sufficient for production of trichodimerol, but not dihydrotrichotetronin in the light (PubMed:28809958). Sor1 iteratively combines three acetyl units and the growing chain is modified by the ketoacyl reductase subunit, and optional by the enoyl reductase subunit in the second cycle (By similarity). The polyketide is then handed over to the PKS sor2, which adds three more acetyl units, and two methyl groups (By similarity). Sor2 releases an aldehyde, which undergoes spontaneous cyclization resulting in the formation of sorbicillin or 2',3'-dihydrosorbicillin (By similarity). The monooxygenase sor5 oxidizes sorbicillin and 2',3'-dihydrosorbicillin to 2',3'-dihydrosorbicillinol and sorbicillinol, respectively (PubMed:29104566). The oxidoreductase sor8 further converts sorbicillinol into oxosorbicillinol (PubMed:29104566). Sorbicillinol is the building block for the other sorbicillinoids such as disorbicillinol, bisvertinolon, dihydrobisvertinolone, and dihydrotrichotetronine (PubMed:29104566, PubMed:28809958). Secondary metabolite biosynthesis. Belongs to the short-chain dehydrogenases/reductases (SDR) family.