The inhibitor of zeaxanthin formation, dithiothreitol, inhibits blue-light-stimulated stomatal opening inVicia faba
✍ Scribed by Alaka Srivastava; Eduardo Zeiger
- Publisher
- Springer-Verlag
- Year
- 1995
- Tongue
- English
- Weight
- 556 KB
- Volume
- 196
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Dithiothreitol (DTT), an inhibitor of violaxanthin de-epoxidation and zeaxanthin formation in chloroplasts, inhibited blue-light-stimulated stomatal opening in epidermal peels of Viciafaba L. in a concentration-dependent fashion. Complete inhibition was observed at 3 mM DTT. The DTT effect was specific for the stomatal response to blue light, and the red-light-stimulated opening, which depends on photosynthetic reactions in the guard cells, was unaffected. Preirradiation of stomata in epidermal peels with increasing photon fluence rates of red light, prior to an incubation in 10 ~tmol.m-2. s-1 of blue light and 100 ~tmol.m-2.s-~ red light, resulted in a DTT-sensitire, blue-light-stimulated opening that was proportional to the fiuence rate of the red light pre-treatment. Guard cells in epidermal peels and guard-cell protoplasts irradiated with red light showed increases in their zeaxanthin content that depended on the fluence rate of red light, or on the incubation time. The increases in zeaxanthin concentration were inhibited by DTT. The obtained results indicate that zeaxanthin could function as a photoreceptor mediating the stomatal responses to blue light.