ISHS Acta Horticulturae 812: III International Symposium on Acclimatization and Establishment of Micropropagated Plants
EFFECT OF GEL MEDIUM AND TIB PROPAGATION TECHNIQUES ON STRESS DEFENSE AND ANATOMY OF SUGARCANE LEAVES DURING ACCLIMATIZATION |
| Authors: | C. Aragón, L. Carvalho, J. González, M. Escalona, S. Amâncio |
| Keywords: | enzymes, ex vitro, in vitro, leaf morphology, oxidative stress |
| Abstract:
Previous results have shown that sugarcane plantlets micropropagated by temporary immersion bioreactors (TIB) show better physiological parameters during acclimatization when compared to gel medium (GM). The present work compares the response of sugarcane plantlets obtained by the two micropropagation techniques, at time zero of transfer to acclimatization, along the first seven days and on days 14 and 21 in ex vitro conditions. The leaves of sugarcane plantlets were stained with specific O2- and H2O2 dyes, respectively NBT and DAB, in order to identify the histological response of stomata and trichomes. GM in vitro culture produced the highest number of trichomes. Plantlets in TIB culture presented trichomes coloured with NBT, their density decreasing with time. Stomata were coloured with both NBT and DAB in GM. At the end of acclimatization (day 21) plantlets from both systems presented the lowest staining of stomata and trichomes. The effect of both techniques was also evaluated through the activity of several enzymes taking part in antioxidant defences (SOD, CAT, GR, APX and DHAR). At the end of the in vitro phase the activity of APX was induced in the GM culture system, while TIB was responsible for increased activities of CAT, GR, and DHAR. By the end of acclimatization, SOD activity was high in both systems; the increase in CAT activity was specific of GM plantlets while the increase in APX was specific to TIB. In conclusion, TIB shows a faster and more efficient mobilization of enzymatic systems against photoxidative stress (CAT, GR, and DHAR) when compared with plantlets propagated by GM. | |
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