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Advances in Proteomics Research in Environmental Stress Response in Plants

precursors were found in soybean roots subjected to flooding stress, which

is most likely associated with reduced cell wall lignification. The findings

reveal that lignification is inhibited by a reduction in reactive oxygen species

(ROS) and jasmonate production (Komatsu et al., 2010).

13.3.5 PLASMA MEMBRANE

The plasma membrane is a phospholipid bilayer with embedded proteins

that separate the inside of the cell (cytosol) from the outside environment.

Membrane proteins make up around half of the total volume of the membrane.

One of the key cellular reactions required for the perception of a stress signal

and its transmission into the cell, which happens predominantly in the plasma

membrane, is a change in gene expression at the protein level (Alexander­

sson et al., 2004). The identification of potential plasma membrane proteins

of Arabidopsis leaves related to cold acclimation was done using a mass

spectrometric approach. After cold acclimation, a substantial alteration in

protein profile was found. MALDI-TOF MS was used to identify a total

of 38 proteins. The proteins that are altered in the amount on the first day

of cold acclimation are mostly linked with membrane repair, membrane

protection against osmotic stress, CO2 fixation enhancement, and proteolysis

(Kawamura & Uemura, 2003).

Plasma membrane proteins were examined using gel-based and gel-free

proteomics methods to investigate changes in the soybean subjected to

flooding stress reveals flood-induced plasma membrane proteins in soybean.

A total of 35 stress-induced new proteins were discovered, the majority of

which are involved in the antioxidative defense mechanism of plants. Nouri

& Komatsu (2010) investigated the impact of PEG (polyethylene glycol)­

induced osmotic stress on the soybean plasma membrane proteome. Plasma

membrane purity was confirmed by assessing ATPase activity after purifica­

tion using a two-phase partitioning technique. Four and eight protein sites

were found to be up and down-regulated, respectively, after PEG treatment

using gel-based proteomics, whereas 11 and 75 proteins were identified as

up-and down-regulated using the nano-LC-MS/MS method. Three isoforms

of the H⁺-ATPase, which are involved in ion efflux and show an increase

under hyperosmotic stress, have been discovered. According to this result,

one protein phosphatase, three isoforms of protein kinases, calnexin, and

phototropin are among the proteins that regulate H⁺-ATPase activity.