Keeping plants under water and light stress conditions showed that seedlings from untreated seeds withered severely after 48 h, while the seedlings grown from treated seeds had more resistance to the stress.
APX2 was strongly induced after 1- and 2-hour exposure to light stress conditions.
The experiment was performed on WT, lut2.1, npq1 (previously shown to have a decreased resistance to oxidative stress under light stress conditions [ 6]) and the double mutant npq1lut2.1.
It has been reported that four central enzymes were involved in microalgal carbon fixation, highly regulated under continuous light stress conditions [ 32].
The chloroplast-located Deg/HtrA proteases were reported to be involved in the degradation of damaged photosynthetic proteins, especially the photosystem II (PSII) reaction center D1 protein under light stress conditions (reviewed [ 24]).
However, when the pellets were subjected to light stress conditions, only the drug content and dissolution profile of the uncoated pellets were changed, as shown in Table 8 and Figure 21.
Under light stress conditions, the decreased expression of CRKs seen in wild type was even more pronounced in the SA mutants sid2 and npr1 and the JA mutant fad3/7/8.
For high light stress conditions, exponentially growing cultures (cell density approximately 5 × 10 cells ml 1) were harvested, and then transferred to 500-ml erlenmeyer flasks (named, 1 9), each containing 250-ml BBM (fresh medium) under continuous exposure of white light (390 770 nm) or blue light (420 500 nm) in light intensity of 1,000 μmol photons m 2 s–1 without day/night cycle.
Therefore, since the light stress conditions used in this work to induce photooxidative damage were rather drastic (1500 μmol photons m-2 s-1 at 6°C), a leakage of O2 from the chloroplast to the cytosol cannot be excluded and therefore an action of vitamin B6 within the cytosol is also possible.
In this context, chloroplastic DHAR must be physiologically indispensable for photoprotection mechanisms particularly when leaves are exposed to high-light stress conditions.
