# Nematoidal Properties of Wild Strains of _Pleurotus ostreatus_
## 4 Discussion
schachtii_ nematode was less susceptible, so we concentrated our study on the cysts, which were trapped and entwined by hyphae. As a result, it was clearly shown that the toxic abilities of hyphae were not uniform in tested strains. Some strains presented higher potential to create toxic hyphal knobs (e.g., Po1 strains) and to kill _C. elegans_ (e.g., all Po1 progenies, Po2 14 dix21, Po2 20 dix2, and Po2 15 dix17) or entwine cysts of _H. schachtii_ (e.g., Po1 5 dix30, Po1 5 dix32, Po1 36 dix30, Po2 15 dix17, Po2 15 dix22, Po2 15 dix23, Po2 20 dix23, Po4 1 dix5, and Po4 1 dix18) than other strains. The mechanism of entwining cysts of _H. schachtii_ seems to be a better method for acquiring nitrogen than capturing nematodes. In the presence of this, pest hyphal knobs were less effectively produced and only a few isolates were able to create a high number of them (Po4, Po1 42 dix30, Po2 15 dix17, Po4 1 dix5, Po4 1 dix18, Po4 1 dix30, and Po4 2 dix17). Entwining and colonization of cysts give a higher dose of nitrogen substrates since cysts are bigger than individual nematodes. Simultaneously, this mode of hyphae action provides better control than killing individual nematodes because cysts are not mobile and contain many larvae. The pot and field experiments showed the possibility of cleaning properties of the _Pleutrotus_ mycelia against _H. schachtii_ nematode. However, the mycelium should be carefully chosen, because _P. ostreatus_ strains may differ in their nematoidal properties. This was clearly visible in the case of the pot experiment, in which the strain Po1 5 dix27 did not reduce the _H. schachtii_ population, and the variant of the experiment with this mycelium was as ineffective as the cultivation of sugar beets. The suppressive properties of soil against _H. schachtii_ was confirmed by [PERSON] and [PERSON] [21]. In their experiment, close to one-third of the cysts but no females from suppressive soil were infested with fungi. The most common fungi isolated from infested cysts were _Fusarium_ sp., _Fusarium oxysporum_, and _Dactylella oviparasitica_. Some unidentified fungi were also isolated from infested cysts. These results combined with ours may support the importance of soil microbiota's role in decreasing the pest population. The potential protective role of _Pleurotus_ mycelia were tested with good results by [PERSON] et al. [22] and [PERSON] et al. [3]. Until now, there have been several studies showing the protective properties of _P. ostreatus_ and other _Pleurotus_ species against _Meloidogyne incognita Meloidogyne javanica_ and _Heterodera goldeni_ and _H. schachtii_[22; 23; 24; 25; 26], and mushrooms or their crude extracts show nematocidal activity against nematodes of genera _Pratylenchus_, _Xiplinema_, _Tylenchorhynchus_, _Tylenchus_, _Helicotylenchus_, _Ditylenchus_, _Psilenchus_, _Aphelenchus_, _Hoplolainus_, _Longidorus_, _Aphelenchoides_, and _Paralongidorus_[26; 27]. Our experiments aimed to select the most effective strains against nematodes. We also wanted to check the diversity of the toxic properties in _P. ostreatus_ wild strains and their progenies, which means that some mechanisms are present in some strains on different levels. This type of studies had not been undertaken before. Previously, the literature reported trans-2-decenediotic acid as a main nematocidal active compound of _P. ostreatus_[8]. It is deposited in droplets produced by hyphal knobs (toxocysts) on the _P. ostreatus_ mycelium; however, other studies found that this compound may not cause as rapid and effective reaction as was observed before [10; 27; 28]. Toxic droplets contain many compounds that may vary among species. A typical _Pleurotus_ toxic droplet measures 1.5-3.0 \(\upmu\)m and, in the case of _P. pulomarrius_, may consist of several toxins such as S-coriolic acid, linoleic acid, panisaldehyde, p-ansilyl alcohol, 1-(4-methoxyphenyl)-1,2-propanediol, and 2-hydroxy-(40-methoxy)-propiophenone [26; 29]. [PERSON] et al.