# Nematoidal Properties of Wild Strains of _Pleurotus ostreatus_
## 4 Discussion
[22] mentioned that a heat-stable and dialyzable low molecular weight molecule is produced and secreted by the hyphae of _Pleurotus_ spp., which inactivates nematode _H. schachtii_[22]. They also observed that the larvae of _H. schachtii_ were attacked by hyphae, which had grown towards the nematode and penetrated it through one of the body orifices [22]. This opinion confirms our research, which clearly shows that the number of hyphal knobs (toxocysts) is not directly correlated with the killing ability (paralysis) of _P. ostreatus_ mycelium. This means that strains that do not produce a high number of toxocysts may achieve good nematocidal activity. Also, the main mode of action displayed by our mycelia against _H. schachtii_ cysts agrees with observations of [PERSON] et al. [22]. The observations by [PERSON] et al. [22] may be explained, and they remain in agreement with the results of [PERSON] et al. [10], which proved that a volatile ketone, 3-octanone, is produced by _P. ostreatus_ and stored in toxocysts and plays an important role in nematocidal activity. This compound, 3-octanone, disrupts the integrity of the cell membrane in _C. elegans_ N2 tissues (neurons, muscles, hypodermis), which results in a massive calcium influx into the mitochondria and then cell death [10]. Fungivory and mechanical wounding induce defense responses and fungal resistance to mites in _P. ostreatus_. This involves the expression of a lectin gene, _Polec2_, which leads to the activation of the reactive oxygen species (ROS)/MAPK signaling pathway, jasmonic acid (JA) regulation, specific gene expression, protein synthesis, and metabolism of toxic substances [29; 30; 31]. [PERSON] et al. [32] described the role of other toxins produced by _P. ostreatus_--Ostreolysin A and Pleurotolysin B (Olya/PlyB), which are pore-forming cytolysins of a larger group of highly homologous proteins called aegerolysins [32]. The activity of 3-octanone was reported as dose-dependent, which agrees with the observations by [PERSON] et al. [22]. The comparable activity was also observed for other C8 compounds, which are structurally similar to 3-octanone, namely 2-octanone and 4-octanone [10]. However, the nematocidal activity was correlated with carbon chain length but not with the position of the carbonyl group in the chain. Thus, 3-decanone was more active than eight carbon chain substances, and on the other hand, a six-carbon chain compound, 3-hexanone, showed limited activity [10]. 3-octanone is one of the C8 volatile compounds wildly prevalent in many fungi and mushrooms, and it is partially responsible for creating the characteristic mushroom flavor and plays informative roles. 3-octanone acts as a self-inhibitor of spore germination in _Penicillium paneum_. It is a signal for sporulation in the _Trichoderma_ genus, when it occurs in low concentration; however, it acts as an inhibitor of spores' sporulation when it is produced in a higher concentration. In _P. ostreatus_, 3-octanone inhibits various bacteria species at the concentrations naturally found in the fruiting bodies of this mushroom [33; 34; 35]. All the described mechanisms of self-protection in _P. ostreatus_ are present in the progeny according to the mechanisms of heredity. Thus, the individuals of the progeny may present various levels of self-protection ability, which was shown in our previous research [12] and in the current study. Taking into consideration the strains that were the most effective, it is worth noticing that Po1 5 dix27 and the maternal strain Po4 clustered separately, whereas the two other strains, Po2 20 dix21 and Po4 2 dix1, clustered in the same group based on the genetic features tested as ISSR bands. For these strains, the same relationships are reflected in the morphological and physiological analysis; however, these features showed more differences among the tested mycelia.