Glycine betaine improves thylakoid membrane function of tobacco leaves under low-temperature stress

Abstract

Glycine betaine (GB) is an effective compatible solute that improves the tolerance in plants to various stresses. We investigated the effects of 2 mM GB applied to the roots of a tobacco (Nicotiana tabacum L.) cultivar on enhancing photosynthesis under low-temperature (LT) stress (5/5 °C, 12/12 h, 300 μmol m -2 s -1 ) and in the subsequent recovery (25/18 °C) from the stress. The net photosynthetic rate, intrinsic efficiency measured as the ratio of variable to maximum fluorescence, and actual efficiency of the photochemistry of photosystem 2 as well as the ATPase activity in the thylakoid membrane decreased, and a distinct K step in the fluorescence transient O-J-I-P appeared under cold stress. Exogenous GB alleviated the decrease in all these parameters. The LT-stress induced the accumulation of 33-66 kDa polypeptides and decreased the proportion of unsaturated fatty acids in the thylakoid membrane. In plants subjected to LT-stress, GB protected these polypeptides from damage and enhanced the proportion of unsaturated fatty acids. An increase in non-radiative energy dissipation (NPQ) may be involved in the improvement of the function of the thylakoid membrane by GB since exogenous GB protected violaxanthin de-epoxidase and enhanced NPQ.

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

“…These results suggest that xanthophyll cycle-dependent thermal dissipation might be one of the most important mechanisms mediating GB-based improvement of PSII functions. This is consistent with the findings of Wang et al (2008) in tobacco.…”

“…Based on the results above (Figs. 6, 7) and our previous studies (Wang et al 2008), GB could improve the efficiency of PSII photochemistry and alleviate photoinhibition under stress conditions. Our data in Fig.…”

“…4, 5, Tables1, 2) in thylakoid membrane, for ∆pH is closely related to the fluidity and integrality, which are determined by its composition. However, GB cannot protect VDE from damage caused by DTT (Wang et al 2008). But it is important to consider that DTT is not a specific inhibitor of VDE and may also interfere with other proteins.…”

ENHANCED TOLERANCE TO LOW TEMPERATURE IN TOBACCO (NICOTIANA TABACUML.) SPRAYED WITH A LOW-TEMPERATURE-RESISTANT AGENT

“…For instance, Glycine betaine (GB) could induce FAD7 (fatty acid desaturase 7) and LOX13 (lypoxygenase 13) expression in the plasma membrane of tomato (Solanum lycopersicum) leaf, which could ameliorate lipid peroxidation, maintain stability and intactness of plasma membrane, and thus increase the resistance of plants to low-temperature stress (Karabudak et al, 2014). A similar alleviating effect of GB was also observed in tobacco (Nicotiana tabacum) leaves suffering low-temperature stress (Wang et al, 2008). GB could protect plasma membrane via lowering H + -ATPase activity, acting as a cryoprotectant against dehydration and keeping reactive oxygen species balance (Fan et al, 2012;Zhang et al, 2010).…”

“…GB is an effective compatible solute that improves the tolerance of plants to various stresses. As a GB non-accumulator species, the effect of applying exogenous GB or expressing foreign GB synthesis-related genes for cold resistance is quite significant in tobacco (Wang et al , 2008). Tobacco line transformed with foreign GB accumulation gene codA presented 33% to 6 times higher CAT activity than wild type in cold stress (Parvanova et al , 2004).…”