With continued growth of global population, the demand for food production is increasing. This is driving the intensification of agriculture and the widespread use of environmentally harmful synthetic fertilizers and pesticides. A shift towards sustainable and environmentally friendly agricultural practices is therefore essential and usage of endophytes represents a promising approach. The aim of this master’s thesis is to establish an optimized system for investigating the tripartite interaction between the endophytic bacteria Bacillus subtilis, the endophytic fungi Fusarium oxysporum, and potato plants, and to further assess the effects of both endophytes and their filtered media on directed potato root growth. After micropropagation of potato plants of the genotypes Désirée and Rywal and their transgenic lines Désirée coi1 (impaired jasmonic acid signaling) and shRBOHD Rywal (reduced production of apoplastic reactive oxygen species), root growth was restricted using physical barriers. At 12, 13, or 14 days after micropropagation, endophytes and their filtered media were inocula-ted in proximity of the plants in various combinations. Directed root growth was quantified five days post inoculation using ImageJ software and expressed as normali-zed root growth. Roots of all plants consistently, and in some cases even statistically significantly, exhibited directed growth towards the physically present bacterium B. subtilis. This effect was even more pronounced in the shRBOHD Rywal transgenic line. Unlike the physically present B. subtilis bacteria, its filtered medium had no effect on directed root growth. On the other hand, the endophytic fungi F. oxysporum did not have such a pronounced effect, since in some cases, its mycelium inhibited root growth. However, potato roots occasionally responded with directed root growth towards filtered F. oxysporum medium. This response was statistically significant in the Désirée coi1 transgenic line.
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