Neral

The standards, including β-Myrcene (90.0%), Limonene (99.0%), terpinolene (94.0%), cis-rose oxide (96.0%), cis-furan linalool oxide (98.0%), linalool (96.0%), 4-terpinenol (95.0%), menthol (98.0%), β-citronellal (99.0%), myrtenol (95.0%), α-terpineol (99.0%), nerol (98.0%), neral, geraniol (97.0%), and geranial (98.0%), were obtained from Sigma-Aldrich (St. Louis, MO, USA). In total, 98% of 4-methyl-2-pentanol (internal standard) was also obtained from Sigma-Aldrich. The purified water used in this research was obtained from a Master Touch purification system (Shanghai, China). Polyvinylpolypyrrolidone (PVPP) was a product of huayueyang (Beijing, China). SYBR^® Premix Ex TaqTM and Plant Total RNA Kit were respectively purchased from TaKaRa Bio (Otsu, Shiga, Japan) and Gene-Better Life Science (Beijing, China). The reverse transcription system kit was purchased from Promega (Madison, WI, USA). All other reagents used in this study were obtained from the Beijing Chemical Works (Beijing, China), unless otherwise specified.

α-Pinene, α-fellandrene, α-terpinene, linalyl acetate, neral, geranial were purchased from Sigma-Aldrich Co. (Italy). β-Pinene, p-cimene, γ-terpinene, terpinolene, linalool, α-terpineol were purchased from Fluka. Mircene, ocimene, neryl acetate, octyl acetate, β-caryophyllene and limonene were purchased from Merck KGaA. Anisole was purchased from Sigma-Aldrich Co (Italy) and used as internal standard.

Methanol (HPLC grade) was purchased from Merck (Darmstadt, Germany) NaCl (analytical grade) was purchased from Sinopharm Chemical Reagent Co., Ltd (Beijing, China); and pure water was obtained from the Milli-Q purification system (Millipore, Bedford, MA).
The chemical standards were purchased as follows: (Z)-3-hexenal, 2-octanol, hexanal, (E)-2-hexenal, geranic acid, phellandrene, β-myrcene, β-damascenone, D-limonene, citronellol, benzyl alcohol, neral, α-terpineol, geranial, geraniol, rose oxide II (cis), rose oxide I (trans), phenylethyl alcohol from Sigma (St. Louis, MO, USA); octanoic acid, pentanal, octanal, nonanal, benzaldehyde, 3-methylbutanal, hexanoic acid, (Z)-3-hexenol, 1-octen-3-ol, heptanol, ethyl acetate, ethyl butyrate, ethyl isobutyrate, butyl acetate, ethyl pentanoate, methyl salicylate, hexyl acetate, (E)-2-hexenoic acid, P-cymene, terpinolene, linalool, 4-terpineol, geranyl acetone from Dr. Ehrenstorfer (Germany); β-ionone from Fluka (Buchs, Switzerland); ethyl hexanoate from Nu-chek (USA); octanol, hexanol, (E)-2-hexenol from Chem Service (USA), and n-alkanes (C₇-C₂₇) from Supelco (Bellefonte, PA).
The automatic solid-phase microextraction (SPME) fibres of 50/30 μm divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) were purchased from Supelco (Bellefonte, PA, USA).