Sirvi Märksõna "Climate change" järgi

Nüüd näidatakse 1 - 3 3

listelement.badge.access-status Embargo ,
Identification of Plant Growth-Promoting Endophytic Fungi from grasslands
(Tartu Ülikool, 2024) Obinwanne, Patricia Kika; Hagh Doust, Niloufar, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Tehnoloogiainstituut
Drought 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.
listelement.badge.access-status Avatud juurdepääs ,
Meltwater of freeze‑thaw cycles drives N2O‑governing microbial communities in a drained peatland forest soil
(Springer Nature, 2023) Kazmi, Fahad Ali; Espenberg, Mikk; Pärn, Jaan; Masta, Mohit; Ranniku, Reti; Thayamkottu, Sandeep; Mander, Ülo
Soil freeze-thaw cycles affect N2O fluxes in high- and mid-latitude regions, but understanding microbial processes behind N2O will help clarify the long-term impact of freeze-thaw on climate change. The aim of this study was to investigate the impacts of freeze-thaw cycles on microbial abundances and N2O emissions in a hemi-boreal drained peatland forest. The soil freeze-thaw experiment involved artificial heating to thaw the topsoil after freezing. Results showed that thawing of the 5 cm topsoil increased soil water content (SWC) and N2O emissions. Microbial analysis demonstrated that the abundance of soil prokaryotes increased with thawing. N2O emissions were negatively correlated with NH4+-N while ammonia-oxidizing archaea and bacteria, including complete ammonia oxidizers, increased their abundance. This indicates a potential nitrification pathway. The abundance of nitrite reductase genes (nirK and nirS) showed a positive correlation with N2O fluxes, while nosZ genes did not increase. The results provide an insight into the impact of soil freeze-thaw cycles on N2O fluxes and the underlying microbial processes. The dynamics of SWC during the thawing period were the most direct driver of the increase in N2O emissions. Incomplete denitrification was the dominant process for the N2O emissions during the thaw. More than 80% of produced N2O was denitrified to inert N2, as shown by high potential N2 emissions. The frequency of freeze-thaw events is expected to increase due to climate change; therefore, determining the underlying microbial processes of the N2O emissions under freeze-thaw is of great importance in predicting possible impacts of climate change in forests.
listelement.badge.access-status Avatud juurdepääs ,
Search for missing components in high VPD-induced stomatal closure pathway
(Tartu Ülikool, 2024) Morozova, Daana; Merilo,Ebe, juhendaja; Tartu Ülikool. Loodus- ja täppisteaduste valdkond; Tartu Ülikool. Tehnoloogiainstituut
Climate warming is associated with rising atmospheric Vapour Pressure Deficit (VPD), which affects plant physiology and production. Some proteins in the high VPD-induced stomatal closure pathway are known (e.g., protein kinase OST1), but there are still missing components. To address this knowledge gap, the study aimed to investigate Arabidopsis mutants defective in selected genes in order to reveal new elements that might be involved in VPD-induced stomata closure. Mutants were selected based on Wang et al. (2020) table of OST1 putative substrates and the expression levels of these genes in guard cells versus mesophyll cells. Experiments were conducted using a gas exchange measurement device to study plants’ stomatal conductance in response to high VPD and a plant stress hormone - abscisic acid (ABA). The study results showed no statistically significant differences in the steady-state stomata conductance and closure responses among mutants and wild-type, suggesting that these genes are not involved in VPD-induced stomata closure. Therefore, more studies are needed to reveal the missing components in the stomatal high VPD-induced closure pathway above OST1. Current results still add knowledge about stomatal behavior in future climatic conditions.