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

Abstract

To investigate the role of glycine betaine in photosynthesis under stress, a transgenic wheat (Triticum aestivum L.) line T6 overaccumulating glycine betaine and its wild type Shi4185 were used. Seedlings were exposed to conditions of drought (30%, PEG-6000), heat (40°C) and their combination. The results revealed ultrastructural damage to the chloroplast and thylakoid lamellae with the withered phenotype by both drought and heat stress, and the damage was exacerbated by the combination of drought and heat. The appearance of a K step in the typical O-J-I-P curve and the decrease of Hill activity indicated a reduction of oxygen evolving complex function caused by stress. The greater damage was found in wild type than T6. Overaccumulation of glycine betaine in T6 could protect lipids in the thylakoid membrane from damage and stabilize the index of unsaturated fatty acids under stress. A lower ratio of monogalactosyl diacylglycerol/digalactosyl diacylglycerol and higher phosphatidylglycerol content in the thylakoid membrane of T6 were also observed under stress. These effects can promote stability of the thylakoid membrane. Otherwise, glycine betaine overaccumulation decreased photoinhibition of PSII under stress. The results also suggest that xanthophyll cycle-dependent non-radiative energy dissipation may be involved in the GB-mediated effects on PSII function under stress conditions.

Exogenous application of glycinebetaine and potassium for improving water relations and grain yield of wheat under drought

“…This beneficial effects of GB has been reported in a number of studies for various crops, particularly those which do not normally accumulate significant amount of GB under drought stress (e.g. Wang et al 2010a;2010b).…”

Consequences of Seed Priming with Salicylic Acid and Hydro Priming on Smooth Vetch Seedling Growth under Water Deficiency

“…Waditee et al (2005), expressed that introduction of genes involved in GB biosynthesis to Arabidopsis plants induces higher accumulation of GB and increases plant tolerance to abiotic stresses including water deficit. Another study conducted by Wang et al (2010) clarified that over-accumulation of glycine betaine in a transgenic wheat line, protects thylakoid membrane from harmful consequences of drought/heat stresses and stabilizes the index of unsaturated fatty acids.…”

Glycinebetaine and abiotic stress tolerance in plants

“…15 Identification of genes of GB biosynthetic pathways has made it easy to engineer GB biosynthesis into non-accumulators by transgenic approach for improved stress tolerance. This approach has been successfuly used in diverse plant species, e.g., Arabidopsis, [25][26][27][28] tobacco, [29][30][31] Brassica, 32,33 Persimmon, 34 tomato, 35,36 maize, 37 rice, 38-40 potato 41 and wheat 42 to improve their abiotic stress tolerance. Among the different GB biosynthetic genes, choline oxidase (codA) from A. globiformis has been widely used for GB production in transgenic plants.…”

“…[51][52][53] GB antagonizes the inhibition of protein biosynthesis 69 and Artiplex. 42 betA, E. coli gene encoding choline dehydrogenase.…”