Sugarcane (Saccharum sp. Hybrid) propagated in headspace renovating systems sho...

• Author(s): Aragón, Carlos ; Carvalho, Luísa A. ; González, Justo ; Escalona, Maritza ; Amâncio, Sara
• Date: 2009
• Persistent ID: http://hdl.handle.net/10400.5/5996
• Origin: Repositório da UTL
• Subject(s): asc-glut cycle; ex vitro growth; in vitro propagation; oxidative stress; peroxiredoxins
• Document Type: Article
• Language: English

Description

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.