Floral maturation and changing air temperatures influence scent volatiles biosynthesis and emission in Jasminum auriculatum Vahl

Benzenoid and terpenoid volatiles are the major compounds contributing to the unique floral scent of Jasminum auriculatum. Biosynthesis and emission of specialized scent metabolites showed maturation stage specific pattern; maximum scent emission was observed when flowers start unfurling and become fully opened under in situ condition. The activities of volatile biosynthesizing enzymes and expressions of several scent-related genes correlated well with the fragrance emission patterns. We also assessed the impact of varying air temperatures (20 degrees C, 25 degrees C, 30 degrees C and 35 degrees C) on the metabolism as well as vaporization of scent volatiles. The contents of both emitted and endogenous volatiles were higher at either 25 degrees C or 30 degrees C and showed relatively lower amounts at both border-range temperatures (20 degrees C and 35 degrees C). Further, the activities of key pathway enzymes and expressions of several scent-related genes under varying temperatures exhibited similar trends with the scent emission patterns. Analysis of non-volatile metabolites from flowers grown under different air temperatures suggests a perturbation occurring in the primary metabolism and immediate precursors of scent compounds. The knowledge base created through these studies shall be helpful in improving the yield of floral scent production from such horticulturally important plants in controlled cultivation systems.