Hagh Doust, Niloufar, juhendajaObinwanne, Patricia KikaTartu Ülikool. Loodus- ja täppisteaduste valdkondTartu Ülikool. Tehnoloogiainstituut2024-06-172024-06-172024https://hdl.handle.net/10062/99642Drought is one of the significant environmental stresses resulting from climate change. Drought can cause a reduction of cultivable land and decreased productivity. This thesis delves into exploring and utilizing endophytic fungi from grasslands to augment plant growth and fortify crop drought stress tolerance. We isolated the endophytic fungi from plants growing naturally in various dry grasslands and saline habitats in Saaremaa, Estonia. We used standard molecular methods for the identification of isolated fungal endophytes. The ability of fungal endophytes to tolerate salt stress was evaluated in the seven most abundant isolates, which were subjected to different concentrations of NaCl (0M, 1M, 2M, and 3M). Our results showed that all seven tested fungal endophytes were halotolerant even though none were isolated from plants growing in saline habitats. Our results indicate that the survival mechanisms of endophytic fungi in dry conditions mirror their survival mechanisms in saline conditions. Isolates Alternaria sp. strain EFP2 (EFP2), Alternaria sp. strain EFP4 (EFP4), and Alternaria alternata strain EFP76 (EFP76) were selected to study their effects on the growth of wheat and barley as model plants under drought. We used a random block design with three factors, namely fungi (four levels), drought (four levels), and soil type (autoclaved and non-autoclaved soil). The experiment was carried out in triplicates and included controls. All three isolates could colonize roots and somewhat promote growth in both model plants. EFP2 protected model plants against water loss, showing relevance in plant water conservation and overall improvement of plant photosynthesis under all drought treatment levels. Among all three isolates tested, EFP4 showed the highest positive impact on growth-promoting characteristics, enabling as much as a 118% increase in total biomass, a 13.5% increase in shoot growth, and a leaf chlorophyll content increase of 18% in wheat across drought treatment levels. EFP2 had the best outcomes for barley, with increases of 6.2%, 3.6%, and 45.8% for total biomass, shoot growth, and leaf chlorophyll content, respectively. It can be concluded that all fungal endophytes that were included in this experiment can be exploited to alleviate the impact of drought stress on crops. Our findings provide a scientific basis for potentially integrating these biological agents into farming systems, aiming to reduce reliance on chemical inputs and improve crop productivity in environmentally stressed areas. These results add to the understanding of plant-microbe interactions and underscore the potential of using endophytic fungi to develop sustainable crop production strategies in the face of global climate challenges.enAttribution-NonCommercial-NoDerivs 3.0 EstoniaClimate changeEnvironmental stressGrasslandEndophytic fungiDroughtSalinityGrowth promotionAlternaria sp.WheatBarleyBiomassShoot lengthLeaf chlorophyllmagistritöödThesis