In planta analysis of cv Royal Gala monoterpene synthase enzyme activity. Full-length monoterpene synthase enzymes were cloned into the pHEX2 plant transformation vector and transiently expressed in tobacco leaves. Selected ion (m/z 93) headspace GC-MS profiles are as follows. A, MdPIN/CAM-RG1: peak 1, α-pinene; peak 2, camphene; peak 3, β-pinene; peak 4, β-myrcene; peak 5, limonene. B, MdOCS-RG1: peak 6, (E)-β-ocimene. C, MdLIS-RG1: peak 7, linalool. D, GUS: empty vector control. Products were confirmed by comparison with authentic standards and/or GC-MS retention indices.