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Biology and Biotechnology of Environmental Stress Tolerance in Plants, Volume 3

transketolase (TK), ribulose-1,5-bisphosphate carboxylase/oxygenase large

subunit (RbcL), and oxygen-evolving enhancer protein 1 (OEE1).

13.3.4 CELL WALL

The cell wall is a supporting structure as well as an exterior physical barrier

that is essential for plant physiology to be stress-free. Cellulose, hemicellu­

loses, and pectin with polymer-like lignin make up the majority of the plant

cell wall (Gall et al., 2015; Voxeur & Hofte, 2016). Because of their critical

involvement in stress sensing and signal transduction between the apoplast

and symplast, cell wall proteome research has gained a lot of interest in

recent years. A comprehensive cell wall protein (CWP) analysis was carried

out in the maize root elongation zone for a better understanding of the under­

lying molecular mechanism of drought stress-responsive adaptation (Zhu et

al., 2007). They found 152 water deficit-responsive proteins and categorized

them into five main categories relying on their function in the cell wall: ROS

metabolism, glucose metabolism, defense, and detoxification, and hydro-

lases. The findings suggest that stress-induced alterations in CWPs include

several mechanisms that are likely to control cell elongation responses.

Changes in protein abundance linked to ROS metabolism increased in

apo-plastic ROS generation (H2O2, oxalate oxidase, APX, Cu/Zn-SOD, Trx

m, germins) in the apical area of the water-stressed root elongation zone.

ECM (extracellular matrix) proteins in chickpea seedlings shoot cell walls

subjected to drought stress were found to change cell wall modification, cell

signaling, metabolism, and cell defense and rescue, harming the molecular

mechanism of drought tolerance in plants (Bhushan et al., 2007).

The cell wall proteome of rice shoots under drought stress was examined

using 2-DE, which showed 100 proteins that were differentially expressed

and may play significant roles in the plant’s dehydration tolerance cascade.

The stress causes changes in proteins involved in stress signaling (NDPK,

involved in γ-phosphate transfers, G-protein signaling, and nucleoside

diphosphate kinase), ROS scavenging and detoxification (APX, thioredoxin,

glyoxalase I, chitinase), molecular chaperones (DnaK, CPN60, and HSP20),

carbohydrate metabolism (phosphoribulokinase, transketolase) and cell

wall modifications (enzymes engaged in the phenylpropanoid biosynthesis

pathway and methyltransferases involved in the methylation of lignin compo­

nents) (Pandey et al., 2010). Lower amounts of Cu/Zn-superoxide dismutase

(Cu/Zn-SOD), four germin-like proteins, lipoxygenases, and glycoprotein