The role of glycine betaine in the protection of plants from stress: clues from transgenic plants

TLDR

Plants acclimate to environmental changes by accumulating compatible solutes, and glycine betaine—a quaternary amine—has been shown to act as a key compatible solute protecting plants from stresses such as salinity and cold, though synthesis varies among species. This review summarizes recent advances in genetically engineering glycine betaine synthesis to examine its protective effects in vivo versus in vitro. Genetic engineering enables the introduction of glycine betaine biosynthetic pathways from microbes and higher plants into GB‑deficient species, facilitating studies of its stress‑protective role.

Abstract

Abstract The acclimation of a plant to a constantly changing environment involves the accumulation of certain organic compounds of low molecular mass, known collectively as compatible solutes, in the cytoplasm. The evidence from numerous investigations of the physiology, genetics, biophysics and biochemistry of plants strongly suggests that glycine betaine (GB), an amphoteric quaternary amine, plays an important role as a compatible solute in plants under various types of environmental stress, such as high levels of salts and low temperature. Plant species vary in their capacity to synthesize GB and some plants, such as spinach and barley, accumulate relatively high levels of GB in their chloroplasts while others, such as Arabidopsis and tobacco, do not synthesize this compound. Genetic engineering has allowed the introduction into GB‐deficient species of biosynthetic pathways to GB from both micro‐organisms and higher plants; this approach has facilitated investigations of the importance of GB in stress protection. In this review, we summarize recent progress in the genetic manipulation of the synthesis of GB, with special emphasis on the relationship between the protective effects of GB in vivo and those documented in vitro .