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Advisor(s)
Abstract(s)
Previous results have shown that sugarcane plantlets
micropropagated in Temporary Immersion Bioreactors
(TIB) demonstrated a better morphology and physiological
behaviour when compared to plantlets propagated in Gelled
Medium (GM). The present work focuses on the onset of
oxidative stress symptoms at transfer to ex vitro and during
acclimatization. The specific ROS being produced were
identified and tissue-located by infiltrating leaves with
specific O2
−.and H2O2 staining dyes, respectively NBT and
DAB. TIB plantlets showed trichomes stained with NBT and
DAB, their density decreasing with time. Stomata were
coloured with NBT and DAB in GM and, at the end of
acclimatization, plantlets from both systems presented the
lowest level of staining of both stomata and trichomes. The
response of the anti-oxidative system was also analysed
through in vitro and in gel enzyme activities and transcription
levels of genes for key response enzymes. At the end of
the in vitro phase, GM plantlets showed higher activities of
APX and MDHAR, while CAT, GR, GT and DHAR
activities increased in TIB. At the end of acclimatization
SOD and CAT increased mainly in TIB, while GM induced
the increase of APX. The immunobloting of peroxiredoxins showed that Prxs were expressed at higher levels in TIB
plantlets, some showing polymerization. The transcription of
genes coding for key response enzymes was strongly upregulated
in GM plantlets. In conclusion and comparing with
GM, TIB produced plantlets closer to autotrophy and with
improved mobilization of the anti-oxidative response.
Description
Keywords
asc-glut cycle ex vitro growth in vitro propagation oxidative stress peroxiredoxins
Pedagogical Context
Citation
"Tropical Plant Biology". ISSN 1935-9756. 2 (2009) 38-50