Solanum lycopersicon Mill. and Nicotiana benthamiana L. under high light show distinct responses to anti-oxidative stress.

Two experimentally important species, Solanum lycopersicon Mill. and Nicotiana benthamiana L., were propagated in vitro under low light (50 micromol m(-2) s(-1)) and transferred to HL (200 micromol m(-2) s(-1)) under a protocol previously developed for grapevine and chestnut. Compared with photooxidative stress parameters already tested in those species, imaging of hydrogen peroxide and superoxide revealed an accumulation on d2-3 and d6 in S. lycopersicon and d1-2 and d5-7 in N. benthamiana. SOD, CAT and APX activities matched ROS accumulation. The expression of the respective transcripts showed a significant increase on d1 in S. lycopersicon while in N. benthamiana a bimodal pattern was found, with peaks on d2 and d7. These results, together with the relative timing of root expansion and new leaf emergence, indicate that these two apparently similar species display different strategies when responding to light stress, evidencing further the uniqueness of the response of each species. The behaviour of N. benthamiana falls closely into the pattern already reported for wood species including grapevine.