# New Detection Method for Fungal Infection in Silver Fir Seeds
## 5 Discussion  
### Role of Chemical Components Identified by GC-MS Method  
Based on the GC-MS analyses, we found that monoterpenes and sesquiterpenes were the main volatile components emitted from _A. alba_ seeds. Previous studies found that essential oils from _A. alba_ seeds contain a large amount of monoterpenes (especially limonene and \(\alpha\)-pinene) [61], whereas _A. alba_ seed hydrolate is rich in sesquiterpenes [62]. Notable among the compounds was pinene (C\({}_{10}\)H\({}_{16}\)), the monoterpene responsible for the pine forest aroma. In addition to their occurrence in pines (_Pinus_ spp.) and hemp (_Cannabis sativa_), \(\alpha\) and \(\beta\)-pinene (as individual compounds or together) are also found in sage (_Salvia_ spp. ), mint basil (_Ocimum mentheafolium_), juniper (_Juniperus communis_), rosmear (_Rosmarinus officinalis_), French lavender (_Lavandula stocchus_), coriander (_Coriandrum sativum_),  
Figure 11: Visualization of the top 15 the most important modeling features selected by the random forest classification method for three considered binary classifications G-W-green vs. white, C-G-control vs. green, C-W-control vs. white. The x-axis has no meaningful units. The name of each feature represents the symbol of the sensor (e.g., W5S) and the time (seconds, e.g., 14) of the measurement. Figure 10: Average of out-of-bag (OOB) error score (classification accuracy) versus the number of estimators used in training of the random forest classification model. Various binary models were compared: C-W–uninfected vs. white samples, C-G–uninfected vs. green samples, G-W–green vs. white samples. Since the number of observations varied between categories (Table 3), the OOB score was normalized to the case of equal populations in the classified categories. caraway (_Cuminum cynimun_), prickly juniper (_Juniperus oxycedrus_), tea tree (_Melaleuca alternifolia_), yarrow (_Achillea millefolium_), lavage (_Liguscium levisticum_), strong dogwood (_Grindelia camporum_), black pepper (_Piper nigrum_), Korean mint (_Agastache rugosa_), and bergamot (_Citrus bergamia_) [63]. Like other terpenes and terpenoids, pinene is produced by the trichomes. It is one of the best-known members of the monoterpenes found in nature. This terpene has two isomers: \(\alpha\)-pinene and \(\beta\)-pinene, each with two enantiomers. Pinene plays a protective role in defence against predators and pests, and \(\alpha\)- and \(\beta\)-pinenes are used to manufacture liver and kidney medicines, as a flavor and fragrance additives, and as fungicides [64]. In a study of mice allergic to egg albumin, the use of \(\alpha\)-pinene reduced the number of nasal, eye, and ear abrasions, suggesting that this substance may be an effective anti-allergic agent [65]. In a study on \(\alpha\)-pinene [66], this compound showed similar efficacy to the drugs indomethacin and gabapentin. The researchers attributed the pain relief at least in part to the \(\alpha\)-pinene. Terpenes are produced by plants act as natural protection against pests and can be used to produce safe and effective pesticides including ones which contain \(\alpha\)-pinene, limonene, citronellol, camphor, and thymol among others [67]. \(\alpha\) and \(\beta\)-pinenes are also used as antimicrobial agents, and in a study of pistachio gum essential oil, in which \(\alpha\)-pinene (75.6%) and \(\beta\)-pinene (9.5%) were the two major constituents, the researchers found inhibitory activity against 9 of 13 bacteria and 3 of 3 pathogenic yeasts [68]. The presence of sesquiterpenes in VOC of incubated seeds is correlated with the detection of _Trichoderma_ in such seeds. Emission of allaoromandchr-9-ene, \(\gamma\)-cadinene, germacrene D, and \(\alpha\)-selinene was reported in _T. asperellum_[69] longifolene and caryophyllene in _T. longibrachiatum_[70]. Resin accumulation in Pinaceae is induced after pathogen or herbivore attack and probably plays an important defensive role as a physical and chemical barrier against invaders [71; 72; 73]. Conifer resin contains mainly terpenes.