Genes for direct methylation of glycine provide high levels of glycinebetaine and abiotic-stress tolerance in Synechococcus and Arabidopsis.
Betaine is an important osmoprotectant, synthesized by many plants in response to abiotic stresses. Almost all known biosynthetic pathways of betaine are two-step oxidations of choline. Recently, a biosynthetic pathway of betaine from glycine, catalyzed by two N-methyltransferase enzymes, was found. Here, the potential role of N-methyltransferase genes for betaine synthesis was examined in a freshwater cyanobacterium, Synechococcus sp. PCC 7942, and in Arabidopsis plants. It was found that the coexpression of N-methyltransferase genes in Synechococcus caused accumulation of a significant amount of betaine and conferred salt tolerance to a freshwater cyanobacterium sufficient for it to become capable of growth in seawater. Arabidopsis plants expressing N-methyltransferase genes also accumulated betaine to a high level in roots, stems, leaves, and flowers and improved seed yield under stress conditions. Betaine levels were higher than those produced by choline-oxidizing enzymes. These results demonstrate the usefulness of glycine N-methyltransferase genes for the improvement of abiotic stress tolerance in crop plants.
Waditee
Rungaroon
R
Research Institute, Graduate School of Environmental and Human Sciences, and School of Agriculture, Meijo University, Nagoya 468-8502, Japan.
Bhuiyan
Md Nazmul H
MN
Rai
Vandna
V
Aoki
Kenji
K
Tanaka
Yoshito
Y
Hibino
Takashi
T
Suzuki
Shigetoshi
S
Takano
Jun
J
Jagendorf
André T
AT
Takabe
Tetsuko
T
Takabe
Teruhiro
T
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001622:Betaine / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000235:genetics; D009994:Osmolar Concentration; D030821:Plants, Genetically Modified / Q000378:metabolism; D046940:Synechococcus / Q000235:genetics / Q000378:metabolism*
D001622:Betaine; D008780:Methyltransferases; D005998:Glycine