CHAPTER 2: Betaine in Sugar Beet
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Published:15 May 2015
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T. Takabe, Y. Tanaka, and T. Takabe, in Betaine: Chemistry, Analysis, Function and Effects, ed. V. R. Preedy, The Royal Society of Chemistry, 2015, pp. 9-28.
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Beta vulgaris is a glycine betaine-accumulating dicotyledonous plant of the Chenopodiaceae family. In plants, glycine betaine is synthesized by two step oxidation of choline in chloroplasts. The first step converts choline to betaine aldehyde, which is the rate-limiting step and catalyzed by choline mono-oxygenase. The second step, conversion of betaine aldehyde to betaine, is catalyzed by betaine aldehyde dehydrogenase. Due to one of the two main sources of sucrose, sugar beet has high economic value. In sugar beet, accumulation levels of betaine are high in leaves and roots including tap roots. Sugar beet is a halophytic plant that can grow under relatively high salinity conditions concomitant with the accumulation of betaine. Recent studies suggest the importance of precursor supply for the large accumulation of betaine. In this chapter, the regulation of biosynthetic genes for betaine synthesis, precursor supply of choline and transport of betaine are discussed. Metabolic engineering and application of betaine from sugar beet are also described.