Geoscience Reference
In-Depth Information
High temperature
Oxidative stress
Disruption of membrane properties,
proteins/enzymes and cellular homeostasis
Transcriptional
factors
Activation of stress-responsive genes
Activation of antioxidant enzymes, free radical
scavengers, signalling molecules and osmoprotectants
ROS detoxification, reactivation of protein and
enzymes and re-establishment of cellular homeostasis
Development of heat tolerance
FIGURe 14.4
A schematic illustration of heat-induced signal
transduction mechanism and development of heat tolerance
in plants.
as an important element in high thermotolerance. In a mutant
wheat line with increased heat resistance, heat treatment
increased relative quantities of linolenic acid (among galacto-
lipids) and
trans
-3-hexaldecanoic acid (among phospholipids),
when compared with the wild type. Currently, it is unknown
whether a higher or a lower degree of membrane lipid satu-
ration is beneficial for high-temperature tolerance. The contri-
bution of lipid and protein components to membrane function
under heat stress needs further investigation. Localisation of
low molecular weight (LMW)-HSPs with chloroplastic mem-
branes upon heat stress suggests that they play a role in protect-
ing photosynthetic electron transport. An important component
of thermotolerance is changes in gene expression. Heat stress is
known to swiftly alter patterns of gene expression (Yang et al.
2006), inducing expression of the HSP complements and inhib-
iting expression of many other genes.
Acclimatisation
of the plant
at low
temperatures
The study of cold-tolerant, herbaceous plants such as wheat,
barley, spinach and the model plant species has enhanced our
understanding of the metabolic and molecular events before,
during and after acclimation. This has assisted greatly in the
