The contribution of carbohydrates including raffinose family oligosaccharides and sugar alcohols to protection of plant cells from oxidative damage.
Recently we have reported that high intracellular levels of galactinol and raffinose in Arabidopsis plants overexpressing the heat shock transcription factor A2 or galactinol synthase are correlated with increased tolerance to methylviologen treatment and salinity or chilling stress, and galactinol and raffinose also are found to effectively protect salicylate from attack by hydroxyl radicals in vitro.1,2 These findings indicate that galactinol and raffinose act not only as osmoprotectants, but also as antioxidants in the leaves of Arabidopsis plants. At the same time, we found that the rate constant (1.1 +/- 0.29 x 10(10) M(-1)s(-1)) for the reaction between stachyose and hydroxyl radicals was higher than those of galactinol and raffinose and typical antioxidants. The accumulation of stachyose was only observed in seeds. Furthermore, glucose, fructose and sucrose which are abundant in higher plants efficiently scavenge hydroxyl radicals. Judging from the radical scavenging activity and the intracellular level of each compound reported here and previously, we suggest that carbohydrates including raffinose family oligosaccharides and sugar alcohols are present at high levels under normal and/or stressfull conditions, and act as antioxidants to protect plant cells from oxidative damage and maintain redox homeostasis.
Nishizawa-Yokoi
Ayako
A
Department of Advanced Bioscience; Faculty of Agriculture; Kinki University; Nara Japan.
Yabuta
Yukinori
Y
Shigeoka
Shigeru
S
Plant Physiol. 1987 Jan;83(1):185-9
16665199
J Exp Bot. 2002 May;53(372):1305-19
11997377
Plant J. 1999 Dec;20(5):509-18
10652123
Science. 1988 Jun 3;240(4857):1302-9
3287616
Plant Cell Environ. 2006 Mar;29(3):409-25
17080595
FEBS Lett. 2001 Nov 23;508(3):438-42
11728468
Plant Physiol. 2008 Jul;147(3):1251-63
18502973
Plant Physiol. 1997 Apr;113(4):1177-83
9112772
Plant J. 2002 Feb;29(4):417-26
11846875
Plant Physiol. 1992 May;99(1):235-8
16668855
Trends Plant Sci. 2004 Oct;9(10):490-8
15465684
Plant Physiol. 2004 Oct;136(2):3148-58
15466240
Planta. 1977 Jan;136(2):163-6
24420322
Anal Biochem. 1998 Nov 1;264(1):98-110
9784193
Plant J. 2006 Nov;48(4):535-47
17059409
Plant Physiol. 1999 Jun;120(2):453-62
10364396
Trends Plant Sci. 2002 Sep;7(9):405-10
12234732