Author(s): Bielawski W, Joy KW
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Abstract In three-week-old pea plants (Pisum sativum L., cv. Little Marvel) grown in the light, total glutathione levels were highest in apex and expanding leaves (1.5 μmol·(g FW)(-1)), and lower (0.4-0.6 μmol·(g FW)(-1)) in older leaves and roots. In the light period, levels in expanded leaves increased by about 40\%, compared with dark values, with lesser increases in roots and apex. In illuminated plants the proportion in the reduced form was 86-88\% in leaves and 80\% in roots, and these values fell during the dark period (to 82\% and 69\%, respectively). Reduced glutathione makes up 65-70\% of the low-molecular-weight thiol in leaves, but over 95\% in roots. Chloroplasts contained about 10\% of the leaf glutathione, at a concentration of 1-2 mM; total glutathione in the chloroplasts, and the proportion of oxidised form (GSSG) increased in light, while NADP(+)/NADPH ratios decreased, indicating both synthesis and active oxidation of glutathione in light. Chloroplasts contained 52\% (young leaf) to 75\% (mature leaf) of the GSSG-reductase (EC 126.96.36.199) activity in the leaves. In roots, over 30\% of the GSSG reductase was in the plastid fraction. Very little GSSG-reductase activity was associated with mitochondria in leaf or root.
This article was published in Planta
and referenced in Transcriptomics: Open Access