Structural–functional state of thylakoid membranes of wheat genotypes under water stress

Abstract

Plants were grown in field conditions in the wide area under normal water supply and severe water deficit. Two wheat (Triticum aestivum L.) genotypes contrasting by architectonics and differing in drought-resistance were used: Giymatli-2/17, short stature, with broad and drooping leaves, drought-sensitive, and Azamatli-95, short stature, with vertically oriented small leaves, drought-tolerant). It was found out that Giymatli-2/17 was characterized by relatively low content of Chl a-protein of PS I (CP I) and beta-subunit of ATP-synthase complex, the high content of proteins in the 33-30.5 kDa region and LHC polypeptides (28-24.5 kDa), the intensive fluorescence at 740 nm and more high photochemical activity of PS II under normal irrigation compared with Azamatli-95. However, the content of CP I (M(r) 115 kDa) and apoprotein of P700 with M(r) 63 kDa insignificantly increases in the drought-resistant genotype Azamatli-95 under extreme water supply condition while their content decreases in drought-sensitive cv Giymatli-2/17. Intensity of synthesis alpha- and beta-subunits of CF(1) (55 and 53.5 kDa) also decreases in Giymatli-2/17. The levels of the core antenna polypeptides of FS II with M(r) 46 and 44.5 kDa (CP47 and CP43) remains stable both in normal, and stressful conditions. At the same time the significant reduction is observed in the content of polypeptides in the 33-30.5 kDa region in the more sensitive genotype Giymatli-2/17. There is an increase in the LHC II polypeptides level in tolerant genotype Azamatli-95 in contrast to Giymatli-2/17 (where the content of these subunits is observed decreasing). The intensity of short wavelength peaks at 687 and 695 nm sharply increases in the fluorescence spectra (77 K) of chloroplasts from sensitive genotype Giymatli-2/17 under water deficiency and there is a stimulation of the ratio of fluorescence band intensity F687/F740. After exposure to drought, cv Giymatli-2/17 shows a larger reduction in the actual PS II photochemical efficiency of chloroplasts than cv Azamatli-95.

Improved drought resistance in a wheat stay-green mutant tasg1 under field conditions

“…Water stress damages thylakoid membranes, disturbs their function, and ultimately decreases photosynthesis and crop yield (Shah and Paulsen 2003, Huseynova et al 2007, Zhao et al 2007). Stay-green mutants are characterized by increased stability of chloroplast membranes and chlorophyll-protein complexes , Park et al 2007.…”

Hydrogen peroxide generation and antioxidant enzyme activities in the leaves and roots of wheat cultivars subjected to long-term soil drought stress

“…Photochemical activity of chloroplasts isolated from control and drought-stressed plants were followed polarographically as O 2 evolution at 20°C using a water-jacketed Clark-type oxygen electrode chamber under illumination with saturating white actinic light (Huseynova et al 2007). Chloroplast concentrations equivalent to 100 lg Chl were used for all measurements.…”

“…This causes not only a substantial damage to photosynthetic pigments, but it also leads to deterioration of thylakoid membranes. In the last years, many experimental evidences have suggested that the chloroplast is the main site of ROS production and the primary site of damage of abiotic stresses: various abiotic stresses (cold, light, and drought) with different mechanisms impair the chloroplast function and lead to the production of reactive oxygen species (due to the overexcitation of the photosystem) that may damage chloroplast proteins, membranes, and pigments (Huseynova et al 2007;Huseynova 2012;Anjum et al 2011;Kannan and Kulandaivelu 2011). Oxidative stress can lead to inhibition of the photosynthesis and respiration processes and, thus, plant growth.…”

Overaccumulation of glycine betaine enhances tolerance of the photosynthetic apparatus to drought and heat stress in wheat

“…Stress damages the thylakoid membrane, disturbs its functions, and ultimately decreases photosynthesis and crop yield (Shah and Paulsen 2003, Huseynova et al 2007, Zhao et al 2007. Preservation of the photosynthetic apparatus is an important strategy for enhancing crop yield under stress.…”