Kuraklık stresi altında Brachypodium distachyon yapraklarının proteom analizi

Among the environmental stress factors, drought is the one that has the most severe effect on agricultural production. Hence, improving the yield under drought stress is one of the most important challenges in agriculture. Drought or water deficit has a direct impact on the cellular metabolism of plant. This impact significantly reduces the growth index and crop yield. A number of studies highlighted the existence of a complex network in the cell upon drought stress. Changes in protein expression play the major role in this complex network. The main strategy to improve crop yield is to integrate all the properties that are required to sustain yield under drought stress and accumulate the most powerful genes and proteins in elite genotypes without any harmful effect on the potential crop yield. This approach will provide the improvement of new plant cultivars that are stable and exhibit high yield potential under drought conditions. In plants, there are number of studies on transcriptome level to elucidate the mechanisms underlying stress response. However, alterations in mRNA levels do not always correlate well with protein levels in the cell due to the post-transcriptional and post-translational modifications. Therefore, transcriptome studies are insufficient for understanding the complex network of stress response, causing a lack of knowledge for the enlightenment of the mechanisms related to stress response. Brachypodium distachyon, model plant for monocot species, exhibits a close relationship to agriculturally and economically important crops. It is also known that Brachypodium distachyon displays high variation in the response against drought stress. This variation will potentially lead to identify new stress-responsive genes and thus proteins. Ongoing transcriptomic analyses in Brachypodium distachyon are available. However, requirement of proteomic analyses is an emerging subject for this plant species. In this study, changes in protein repertoire of Brachypodium distachyon leaves after exposing individuals to time-dependent drought stress (4, 8 and 12 day application of drought) were described. Based on two-dimensional difference gel electrophoresis (2D-DIGE), constructed with 3 replicates, and combined mass spectrometry (MS) experiments, a proteomic approach was carried out for this purpose. The comparison of the resulting proteomic data highlighted differentially expressed proteins (DEPs) upon drought stress. 37 differentially expressed proteins were detected via statistical evaluation of relative spot densities and among these one, thirteen DEPs were identified by MS and classified according to their functions. The role and relation of DEPs in drought response of Brachypodium distachyon were discussed. The biological functions of DEPs included roles in photosynthesis, protein folding, antioxidant mechanism and metabolic processes. It has been highlighted that there is a significant degree of overlapping between metabolic alterations induced by drought stress. The identified proteins in this study could serve as potential biomarkers for the selection of drought-tolerant Brachypodium distachyon plants as well as its relatives like wheat, barley and rye. Furthermore, identified proteins will contribute on the studies on development of drought-resistant crop species such as wheat, oat and barley, which are close relatives of Brachypodium distachyon.