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Carleton University (2012)

Functional analysis of FLRS and FLR in wheat during drought stress

Alsaiari Sarah

Titre : Functional analysis of FLRS and FLR in wheat during drought stress

Auteur : Alsaiari Sarah

Université de soutenance : Carleton University

Grade : Master of Science M.Sc. 2012

The MAPK cascade plays an important role in intracellular signal transduction processes involved in response to abiotic stress such as drought, high salinity, and low temperature. Plants respond to abiotic stress through the activation and coordination of different pathways. The regulation of some of these pathways requires the phosphorylation of proteins by MAP kinase cascade. This protein kinase cascade is composed of three classes of enzymes : MAPK, MAPK kinase (MAPKK), and MAPK kinase kinase (MAPKKK). Our study has implicated that at the transcriptional level, the level of FLR (a wheat MAPKKK) and FLRS (a wheat MAPK) gene transcripts do not change during drought stress. This suggests that FLR and FLRS may not play a role in wheat response to drought stress at the transcriptional level. However, ERK-type MAPKs (including FLRS) may be involved in the signalling pathway at post-translational level as seen by Western blot analysis with specific phospho-ERK antibody. Programmed cell death (PCD) is associated with the accumulation of reactive oxygen species (ROS) in wheat and the level of PCD increased during drought stress. The transcription of Wcbf2-2 gene did not change during drought stress in the presence of ERK inhibitor or general protein kinase inhibitor, suggesting Wtcbf2-2 did not respond to drought stress in wheat. This may also indicate that Wtcbf2-2 might not be downstream of ERK-type MAPK pathway in wheat. Bioinformatics analysis has indicated that there is no significant difference in FLR and FLRS expression level between drought tolerant and drought sensitive genotypes. Motif analysis has identified the possible phosphorylation sites for FLR as T104, T149, and T958, and for FLRS as T365, T617, T1028 and T1753. Work in this thesis shed light on the role of MAPK in plant response to abiotic stress and more specifically drought stress.


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