Monoterpene synthase (mono-TPS) involved in the biosynthesis of monoterpenes natural products, constituent of coffee beverage aroma (PubMed:23398891). Catalyzes the conversion of (2E)-geranyl diphosphate (GPP) into linalool and beta-myrcene, and, as minor products, cis-ocimene and trans-ocimene (PubMed:23398891). Not able to use geranylgeranyl pyrophosphate (GGPP) and farnesyl pyrophosphate (FPP) as substrates (PubMed:23398891). (2E)-geranyl diphosphate = beta-myrcene + diphosphate (2E)-geranyl diphosphate + H2O = diphosphate + linalool (2E)-geranyl diphosphate = (Z)-beta-ocimene + diphosphate (2E)-geranyl diphosphate = (E)-beta-ocimene + diphosphate Binds 3 Mg(2+) or Mn(2+) ions per subunit. Secondary metabolite biosynthesis; terpenoid biosynthesis. Monomer. Expressed in flowers and fruits. Observed at early stages of flowers and fruits development (PubMed:23398891). Expressed in flowers and drupes at 10 weeks after pollination, and, at low levels, in fruits at 15 weeks of ripening (PubMed:23398891). The Asp-Asp-Xaa-Xaa-Asp/Glu (DDXXD/E) motif is important for the catalytic activity, presumably through binding to Mg(2+). Belongs to the terpene synthase family. Tpsb subfamily. Truncated N-terminus.