ฉันเป็นคนไม่ได้เรียนหนังสือIndiscriminate release of metal oxide nanoparticles (NPs) into the environment due to anthropogenic
activities has become a serious threat to the ecological system including plants. The present study
assesses the toxicity of nano-CuO on rice (Oryza sativa cv. Swarna) seedlings. Three different levels of
stress (0.5 mM, 1.0 mM and 1.5 mM suspensions of copper II oxide, <50 nm particle size) were imposed
and seedling growth performance was studied along control at 7 and 14 d of experiment. Modulation of
ascorbate–glutathione cycle, membrane damage, in vivo ROS detection, foliar H2O2 and proline accumulation
under nano-CuO stress were investigated in detail to get an overview of nano-stress response of
rice. Seed germination percentage was significantly reduced under stress. Higher uptake of Evans blue
by nano-CuO stressed roots over control indicates loss of root cells viability. Presence of dark blue and
deep brown spots on leaves evident after histochemical staining with NBT and DAB respectively indicate
severe oxidative burst under nano-copper stress. APX activity was found to be significantly increased in
1.0 and 1.5 mM CuO treatments. Nevertheless, elevated APX activity might be insufficient to scavenge all
H2O2 produced in excess under nano-CuO stress. That may be the reason why stressed leaves accumulated
significantly higher H2O2 instead of having enhanced APX activity. In addition, increased GR activity
coupled with isolated increase in GSH/GSSG ratio does not seem to prevent cells from oxidative damages,
as evident from higher MDA level in leaves of nano-CuO stressed seedlings over control. Enhanced proline
accumulation also does not give much protection against nano-CuO stress. Decline in carotenoids level
might be another determining factor of meager performance of rice seedlings in combating nano-CuO
stress induced oxidative damages.
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