| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2017305 | Plant Science | 2012 | 10 Pages |
Stress-responsive dihydroxy B-ring-substituted flavonoids have great potential to inhibit the generation of reactive oxygen species (ROS) and reduce the levels of ROS once they are formed, i.e., to perform antioxidant functions. These flavonoids are located within or in the proximity of centers of ROS generation in severely stressed plants. Efficient mechanisms have been recently identified for the transport of flavonoids from the endoplasmic reticulum, the site of their biosynthesis, to different cellular compartments. The mechanism underlying flavonoid-mediated ROS reduction in plants is still unclear. ‘Antioxidant’ flavonoids are found in the chloroplast, which suggests a role as scavengers of singlet oxygen and stabilizers of the chloroplast outer envelope membrane. Dihydroxy B-ring substituted flavonoids are present in the nucleus of mesophyll cells and may inhibit ROS-generation making complexes with Fe and Cu ions. The genes that govern the biosynthesis of antioxidant flavonoids are present in liverworts and mosses and are mostly up-regulated as a consequence of severe stress. This suggests that the antioxidant flavonoid metabolism is a robust trait of terrestrial plants. Vacuolar dihydroxy B-ring flavonoids have been reported to serve as co-substrates for vacuolar peroxidases to reduce H2O2 escape from the chloroplast, following the depletion of ascorbate peroxidase activity. Antioxidant flavonoids may effectively control key steps of cell growth and differentiation, thus acting regulating the development of the whole plant and individual organs.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Stress-responsive dihydroxy B-ring-substituted flavonoids are effective antioxidants. ► The metabolism of dihydroxy B-ring-substituted flavonoids is a robust trait of terrestrial plants. ► Sub-cellular flavonoid distribution is suitable for antioxidant functions. ► Vacuolar flavonoids may scavenge hydrogen peroxide. ► Antioxidant flavonoids have great potential as developmental regulators.
