Petunia Flower Volatile Analysis

Petunia flower volatiles were collected by a closed-loop stripping method and analyzed by GC-MS as described previously^{66 (link)} with minor modifications. Briefly, volatiles were collected from 20:00 to 21:00 h from a minimum of three 2-day-old flowers per biological replicate. Absorbed volatiles were eluted from collection traps containing 20 mg of Porapak Q (80-100 mesh) (Waters, Milford, MA) with 200 μl DCM supplemented with 1 μg of naphthalene as internal standard. For the analysis of internal pools, 100 mg of ground tissue was extracted twice at 4 °C with 500 μL DCM containing 1 μg naphthalene as internal standard. The extracts were pooled together and concentrated to about 200 μL under a mild stream of nitrogen gas. Samples were analyzed on an Agilent 7890B-5977B GC-MS system using an analytical method translated from established method with Agilent 6890N-5975B GC-MS system as previously described^{66 (link)}. Quantitation of different volatile compounds was performed based on standard curves generated with authentic standards.