## 2 Results and Discussion
The last three clusters were represented by the samples contaminated with _A. tenuissima_ (3 rd), _F. oxysporum_ (4 th), and _F. sambucinum_ (5 th), respectively. The predominant compounds included: 1-octane-3-ol, benzothiazazole, \(\beta\)-cedrene, isobuthylbenzene, and 1,2,3-trimethylbenzene (At), 1,2,3-trimethylcyclopentane, 1-ethyl-4-methylbenzene, 2-methylheptane, 3-methyloctane, 4-methyloctane, 4-heptanone (Fo), and 3-octanol, valencene, chamigrene, dimethyl sulfide, \(\alpha\)-cubehene, \(\alpha\)-guaiene, (+)-epi-bicyclosesquiphellandrene, and spirou[3.4]octen-5-one (Fs). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **PC 1** & **PC 2** & **PC 3** & **PC 4** \\ \hline Control & 0.128 & 0.001 & 0.840 & 0.018 \\ _A. alternata_ & 0.048 & 0.070 & 0.015 & 0.003 \\ _A. solani_ & 0.120 & 0.087 & 0.037 & 0.006 \\ _A. tenuissima_ & 0.093 & 0.001 & 0.007 & 0.751 \\ _C. cocodes_ & 0.041 & 0.051 & 0.038 & 0.005 \\ _F. oxysporum_ & 0.752 & 0.050 & 0.115 & 0.078 \\ _F. sambucinum_ & 0.206 & 0.783 & 0.000 & 0.005 \\ _P. carootororum_ & 0.005 & 0.001 & 0.018 & 0.073 \\ _P. exigua_ & 0.001 & 0.084 & 0.014 & 0.000 \\ _R. solani_ & 0.147 & 0.120 & 0.014 & 0.001 \\ _S. scabiei_ & 0.154 & 0.162 & 0.013 & 0.174 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Squared cosines of the observations. Figure 1: Principal component analysis (PCA) biplot of volatile compounds determined in potato tuber samples contaminated with different phytopathogens. Fo—_F. oxysporum_; Fs—_F. sambucinum_; Aa—_A. alternata_; As—_A. solani_; At—_A. tenuissima_; Rs—_R. solani_; Cc—_C. cocodes_; Pe—_P. exigua_; Ss—_S. scabiei_; Pc—_P. carootororum_. A characteristic group of compounds identified in the sample contaminated with _F. sambucinum_ are sesquiterpenenes such as valencene, \(\alpha\)-cubebene, \(\alpha\)-guaiene, chamigrene, and (+)-epi-bicyclosesquiphellandrene. Moreover, \(\beta\)-cedrene was detected only in the sample contaminated with A. tenuissima (Table S1 and Table 3). [PERSON] and [PERSON] (2017) in an extensive review concerning the relationship between the spoilage of agricultural products and volatile metabolites of fungi cited the studies conducted by [PERSON] et al. (2018), which showed a correlation between the release of volatile compounds by Aspergillus fungi, including sesquiterpenes, and the initiation of mycotoxin biosynthesis. [PERSON] et al. (2018), in turn, confirmed the ability of fungi to synthesize eucalypt (1,8-cineole). In this study, eucalypt was identified only in the sample contaminated with _S. scabiei_ (Tables 2 and 3). Another compound representing the terpene group is D-limonene, the monoterpene, which was found only in the contaminated samples, in the case of _A. alternata, C. cocodes, P. carovorum_, and _S. scabiei_. In these samples, D-limonene was marked in the large relative content of 34.19, 20.18, 32.72, and 25.24% peak area, respectively (Table 3). D-limonene was commonly detected as a metabolite of fungi (2017; 2018; 2019). D-limonene and \(\alpha\)-pinene identified for all the tested pathogens are regarded as the markers of potato phytotoxicity and have also been found to inhibit sprouting (2019). In turn, octanone reported for _C. cocodes_ samples was previously detected in the early stages of potato storage (2019). 3-carene was also detected in several trials; however, compared to the control sample before storage, the highest relative content of this chemical was in the headspace from potato tubers contaminated with _A. solani_ (9.14% of the total peak area). As in the case of D-limonene, no 3-carene was detected in the control sample after storage. 3-carene has also been recognized to have antimicrobial activities (2019). The studies of [PERSON] et al. (2019) confirmed the presence of dimethyl disulfide in the headspace of containers filled with potato tubers contaminated with two pathogens _Erwinia carovorora_ var. _carovorora_ and _Fusarium reseum_ var. _sambucinum_. In this study, dimethyl disulfide was found in the sample infected with _F.