| 19140950 |
Tossi V, Lamattina L, Cassia R: An increase in the concentration of abscisic acid is critical for nitric oxide-mediated plant adaptive responses to UV-B irradiation. New Phytol. 2009 Jan 8.
* Here, the link between UV-B stimulus and the abscisic acid (ABA)-induced nitric oxide (NO) synthesis pathway was studied in leaves of maize (Zea mays). * The ABA concentration increased by 100% in UV-B irradiated leaves. Leaves of viviparous 14 (vp14), a mutant defective in ABA synthesis, were more sensitive to UV-B-induced damage than those of the wild type (wt). ABA supplementation attenuated UV-B-induced damage in both the wt and vp14. The hydrogen peroxide (H (2) O (2)) concentration increased in the irradiated wt, but changed only slightly in vp14. This increase was prevented by diphenylene iodonium (DPI), an inhibitor of NADPH oxidase (pNOX). * NO was detected using the fluorophore 4,5-diamino-fluorescein diacetate (DAF-2DA). DAF-2DA fluorescence increased twofold in UV-B-irradiated wt leaves but not in vp14 leaves. H (2) O (2) and NO production was restored in vp14 plants supplied with 100 microM ABA. Catalase, DPI and the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) partially blocked UV-B-induced NO accumulation, suggesting that H (2) O (2) as well as NOS-like activity is required for a full plant response to UV-B. NO protects against UV-B-induced cell damage. * Our results suggest that UV-B perception triggers an increase in ABA concentration, which activates pNOX and H (2) O (2 ) generation, and that an NOS-like-dependent mechanism increases NO production to maintain cell homeostasis and attenuate UV-B-derived cell damage. |
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