3. Different Timings of Antioxidative Response of in vitro Propagated Plants under Light Stress

Three plant species, the worldwide economically relevant crops Vitis vinifera L.and Solanum lycopersicon Mill. and the model tobacco Nicotiana benthamiana L. were propagated in vitro under low light (50 μmol m-2s-1) and transferred to HL (200 μmol m-2s-1) for 7 days. To identify oxidative stress symptoms and recovery we monitored the activity of enzymes related with the ascorbate-glutathione cycle and the expression of the genes that code for these enzymes. SOD, CAT and APX activities were higher on d2-3 and d6 in S. lycopersicon and on d1-2 and d5-7 in N. benthamiana and V. vinifera. The expression of the respective transcripts showed a significant increase on d1 in S. lycopersicon while in N. benthamiana and V. vinifera a bimodal pattern was found, with peaks on d2 and d7. These results indicate that the two Solanaceae display different strategies when responding to light stress, evidencing further the uniqueness of the response of each species. Moreover, the behaviour of N. benthamiana falls closely into the pattern of a woody species such as V. vinifera.