THESIS
2019
xiii leaves, 144 pages : illustrations ; 30 cm
Abstract
Thigmorphogenesis is the response of plants to environmental mechanical stimuli (like
wind, raindrops, touch etc.) which can cause significant morphogenetic changes over
times. After applied periodic touching stimulus in a long term period, Arabidopsis
thaliana presents a shorter inflorescence length, delayed flowering day and smaller
rosette radius. Which are consistent with the previous study. In cellular level, many
molecular signals and phytohormones are involved in this response.
In this study,
15N-stable isotope labeling in Arabidopsis (SILIA) combined with the high-resolution
mass spectrometer approach was used to study new signaling components
after 40 seconds touch treatment applied (1 touch/ second). Phosphorylation changes
were the mainly target for profiling because...[
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Thigmorphogenesis is the response of plants to environmental mechanical stimuli (like
wind, raindrops, touch etc.) which can cause significant morphogenetic changes over
times. After applied periodic touching stimulus in a long term period, Arabidopsis
thaliana presents a shorter inflorescence length, delayed flowering day and smaller
rosette radius. Which are consistent with the previous study. In cellular level, many
molecular signals and phytohormones are involved in this response.
In this study,
15N-stable isotope labeling in Arabidopsis (SILIA) combined with the high-resolution
mass spectrometer approach was used to study new signaling components
after 40 seconds touch treatment applied (1 touch/ second). Phosphorylation changes
were the mainly target for profiling because its importance. In total, 4, 895 unique
phosphopeptides were identified at least twice experimentally. And 579 unique phosphopeptides were novel ones. As for the quantification result, 24 phosphopeptides
driven from 34 proteins were touch regulated. Selected from these 34 touch regulated
proteins, both MAP Kinase Kinase 2 (MKK2) and an previously unknown protein that
being named Touch-Regulated Phosphoprotein 1 (TREPH1) were continued with the
functional study. Loss-of-function mutants mkk2 and treph1-1 were insensitive to
gentle touch and exhibits earlier bolting under mechanical stresses compared with wild
type. Transformation of S625A mutant TREPH1 protein into the loss-of-function treph1-1 background failed to complement its abnormal thigmomorphogenesis. Furthermore,
transcriptomics analysis of the loss-of-function treph1-1 and mkk2 mutants showed a
reduced gene expression in touch-inducible genes. Confocal and super-resolution
microscopy analysis of TREPH1 protein subcellular localization revealed that it located
on the membrane of the plastid envelope and plasma membrane. All these functional
data support these two proteins (especially the phosphorylation site being identified by
LC-MS/ MS) are essential for Arabidopsis mechanical stimuli.
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