TITLE:
A dual role of selenium in the growth control of seedlings of Stylosanthes humilis
AUTHORS:
Dimas Mendes Ribeiro, Ana Maria Mapeli, Werner Camargos Antunes, Raimundo Santos Barros
KEYWORDS:
Aluminium, Ethylene, Growth Inhibition, Reactive Oxygenspecies, Selenate, Townsville Stylo
JOURNAL NAME:
Agricultural Sciences,
Vol.2 No.2,
May
20,
2011
ABSTRACT: The growth of seedlings of Townsville sytlo (Stylosanthes humilis H.B.K.) is inhibited by aluminium (Al) ions, their elongation being re-covered with sodium selenate at 1.0 µM. Methyl viologen and hydrogen peroxide, reactive oxy-gen species (ROS)-generating compounds, also inhibited seedling elongation and again growth was relieved by selenate. Selenate, thus, seemed to be operating as a ROS quencher, since N-acetylcysteine (NAC), an antioxidant com-pound, also stimulated largely the growth of Al-inhibited seedlings. At a higher concentra-tion (0.1 mM), however, selenate inhibited seed-ling growth and elongation was recovered by NAC. Ethylene production by selenate plus NAC-treated seedlings was very higher and thus the gaseous hormone was not responsible for the seedling growth inhibition caused by sele-nate. Hence, it seems that at high levels sele-nate operates as a ROS-generating compound whose effects were counteracted by NAC. It can be deduced that, at low concentration, sele-nates behave as a ROS quencher and at high level as a ROS-promoting species.