Volatile compounds of endophyte-free and infected tall fescue (Festuca arundinacea Schreb.)

Volatile compounds produced by intact plants and ground leaf tissue from endophyte-infected (E+) and endophyte-free (E-) tall fescue (Festuca arundinacea Schreb.) were collected by a purge-and-trap procedure and analyzed by gas chromatography/mass spectrometry The volatile compound profile from ground leaf tissue was similar between E+ and E- clonal plants; however, the sheaths of E + clonal plants produced higher levels of 1-octen-3-ol, a characteristic volatile compound derived from lipid peroxidation in fungi, which was absent in E- clonal plants. Intact plants produced fewer volatiles than macerated leaves. At 25 °C, (Z)3-hexen-1-ol acetate was the most abundant compound, accounting for 77 and 89% of the total volatile emission from E+ and Eplants, respectively. Higher temperature (32 °C) significantly reduced the production of (Z)-3-hexen-l-ol acetate. Nonanal was the most abundant compound at 32 °C accounting for 52 and 45% of the total volatile emission from E+ and E- plants. Treatment of E+ and E- plants with jasmonic acid (JA) dramatically altered the volatile compound profile. The levels of (E)-β-ocimene increased more than 200-fold and accounted for at least, 43% of the total volatile emissign. Although the presence of endophyte resulted in some qualitative and quantitative differences in the production of volatile compounds, they are unlikely to account for the differences in insect resistance between E+ and E- plants. Nevertheless, the production of a unique spectrum of volatiles after JA treatment may represent a significant plant-based defense response in tall fescue that is independent of endophyte.