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

in excess under salinity stress. By comparing the reference wheat variety

Chinese Spring (CS) to a salt-tolerant amphiploid, the influence of salinity

on the mitochondrial protein was studied (AMP). The AMP had a greater

abundance of Mn-SOD, MDH (malate dehydrogenase), aconitase, SHMT

(serine hydroxymethyltransferase), and β-CAS (β-cyanoalanine synthase)

than CS, indicating genotypic variations in mitochondrial composition. In

addition, they found organ-specific differences in proteins such as aspartate

aminotransferase, GDH (up-regulated in the shoot, down-regulated in root)

(Jacoby et al., 2013).

13.3.3 CHLOROPLAST

Abiotic stresses like drought, salt, high or low temperatures, heavy metal

cause a significant impact on chloroplasts which is the sites of the photosyn­

thetic machinery. Stress-induced alterations in cellular redox balance, reduc­

tion in CO2 fixation, and NADP⁺ regeneration through the Calvin cycle make

the photosynthetic apparatus very sensitive. As a result, the photosynthetic

electron transport chain becomes too reduced, resulting in the formation

of superoxide radicals and singlet oxygen in the chloroplasts. Excess ROS

inhibits photosynthesis-related chloroplast protein activities (Hossain et al.,

2012; Kosava et al., 2018).

So far, only a few research have been conducted on the abiotic stress

responses in chloroplast proteomes. The impact of short-term salt stress on

maize chloroplast’s proteome was investigated using 2DE MALDI-TOF

during the early phases of salt stress (Zorb et al., 2009). This study revealed

that ferredoxin-NADP reductase, 23 kDa PSII, FtsH-like; ATP synthase

CF1ε were up-regulated and ATP synthase CF1α, LHC a/b binding proteins

were down-regulated.

In a soybean plant, the response to ozone stress and alterations in chloro­

plast protein expressions were extensively researched (Ahsan et al., 2010).

The study found 32 chloroplast proteins that were differentially expressed.

Under stress, several proteins involved in photosystem I/II and carbon

absorption decreased, possibly explaining why photosynthetic activity

dropped in response to ozone. On the other hand, protein responsible for

carbon metabolism and antioxidant defense was increased. The authors

concluded that sucrose availability may play a crucial role in oxidative stress

signaling and antioxidative process regulatory pathways, as well as the