Terpene cyclase involved in the biosynthesis of culmorin, a tricyclic sesquiterpene diol reported to have antifungal activity and some phytotoxicity to wheat coleoptile tissue, contributing to Fusarium head blight disease (PubMed:19880637) (Probable). The terpene cyclase CLM1 is responsible for the cyclization of farnesyl diphosphate into the intermediate longiborneol (PubMed:19880637). Longiborneol is then hydroxylated in a regio- and endo-stereoselective manner at position C-11 by the cytochrome P450 monooxygenase CLM2 to produce culmorin (PubMed:26673640). Additional non-specific oxygenases are also able to hydroxylate longiborneol at other sites than C-11 leading to 3-hydroxylongiborneol, 5-hydroxylongiborneol, 12-hydroxylongiborneol and 15-hydroxylongiborneol (PubMed:26673640). Moreover, another oxygenase capable of installing a C-11 exo-hydroxy group in longiborneol can also yield 11-epi-acetylculmorin (PubMed:26673640). The production of these longiborneol derivatives is dwarfed by the high abundance of culmorin, suggesting that CLM2 displays superior enzymatic activity to the unidentified, possibly promiscuous, additional oxygenases (PubMed:26673640). Mycotoxin biosynthesis. Expressed under trichothecene-inducing conditions. Leads to complete loss of culmorin production (PubMed:19880637). Does not affect the trichothecene biosynthetic pathway since 15-acetyldeoxynivalenol (15ADON) is still produced (PubMed:19880637). Keeps the ability to convert exogenously added longiborneol to culmorin (PubMed:19880637). Longiborneol synthase CLM1 is a potential target to reduce Fusarium head blight disease. 3D-structure modeling based on known 3D-structure of losely related enzymes has been used for screening of hypothetical inhibitors of CLM1 catalytic activity. Belongs to the trichodiene synthase family.