Fragaria nilgerrensis, Schltdl. ex J.Gay

Mehmood, Nasir, Yuan, Yuan, Ali, Mohammed, Ali, Muhammad, Iftikhar, Junaid, Cheng, Chunzhen, Lyu, Meiling & Wu, Binghua, 2021, Early transcriptional response of terpenoid metabolism to Colletotrichum gloeosporioides in a resistant wild strawberry Fragaria nilgerrensis, Phytochemistry (112590) 181, pp. 1-12 : 7

4.2. Isolation of phytochemical and volatile compounds from F. nilgerrensis leaves

At different hours (0, 3, 6, 12, 18, 24, 48 and 72 h) after infected with C. gloeosporioides , leaves were removed and collected from the plants, frozen immediately in liquid nitrogen and then stored at 80 ◦ C for future use. Each cryopreserved sample was homogenized in liquid nitrogen by using pestle and mortar. One gram of the powdered samples was mixed with 2 ml saturated NaCl in a 20 ml-head-space vial, in which an internal standard (10 μl of 8.08 mg /L 2,6-dimethyl-4-heptanone (cat. Nr. W353701 from Sigma–Aldrich, Shanghai, China) was added. Before subjecting the mixtures for SPME extraction, each vial was heated at 60 ◦ C for 10 min. Subsequently, the headspace of the sample vial was exposed to a 65 μm divinylbenzene/carboxen/polydimethylsilioxan fiber (Supelco, Bellefonte, PA, USA) for 20 min at 60 ◦ C to complete the extraction. Relative abundance of the compounds was quantified by peak area determination and normalized to the mass of the internal standard. We pooled samples from three plants for one biological replication and the experiment was performed twice which gave similar results. Data are shown as mean without significant test in the Results section.