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.
E. Delhaize and P. R. Ryan, “Aluminum toxicity and tolerance in plants”, Plant Physiology, Vol.107, 1995, pp. 315-321.
L. V. Kochian, O. A. Hoekenga and M. A Pin-eros, “How do crop plants tolerate acid soils? Mechanisms of aluminium tolerance and phosphorous efficiency,” Annual Review of Plant Biology, Vol. 55, 2004, pp. 459-493.
S. J. Neill, R. Desikan and J. T. Hancock, “Hydrogen peroxide sig-nalling,” Current Opinion in Plant Biology, vol. 5, 2002, pp. 388-395.
K. Oracz, H. E. M. Bouteau, J. M. Farrant, K. Cooper, M. Belghazi, C. Job et al., “ROS production and pro-tein oxidation as a novel mechanism for seed dormancy alle-viation,” The Plant Journal, vol. 50, 2007, pp. 452-465.
J. Bailey-Serres and R. M. Mittler, “The roles of reactive oxygen species im plant cells,” Plant Physiology, Vol. 141, 2006, pp. 331.
R. Carol and L. Dolan, “The role of reactive oxygen species in cell growth: Lessons from root hairs”. Journal of Experimental Botany, Vol. 57, 2006, pp. 1829-1834.
M. Sepp?nen, M. Turakainen and H. Hartikainen, “Selenium ef-fects on oxidative stress in potato,” Plant Science, Vol. 165, 2003, pp. 311-319.
M. Filek, R. Keskinen, H. Hartikainen, I. Szarejko, A. Janiak, Z. Miszalski et al.,” The protective role of selenium in rape seedlings subjected to cadmium stress”, Journal of Plant Physiology, Vol. 165, 2008, pp. 833-844.
H. Hartikainen, T. Xue and V. Piironen, “Sele-nium as an antioxidant and pro-oxidant in ryegrass,” Plant and Soil, Vol. 225, 2000, pp. 193-200.
M. Mora, L. Pinilla, A. Rosas and P. Cartes, “Selenium uptake and its influence on the antioxidative system of white clover as affected by lime and phosphorus fertilization,” Plant and Soil, Vol. 303, 2008, pp. 139-149.
T. A. Brown and A. Shrift, “Selenium: Toxicity and tolerance in higher plants”, Biological Review, vol. 57, 1982, pp. 59-84.
D. C. Eustice, F. J. Kull and A. Shrift, “Selenium toxicity: Aminoacylation and peptide bond forma-tion with selenomethionine”, Plant Physiology, Vol. 67, 1981, pp. 1054-1058.
J. R. Konze, N. Schilling and H. Kende, “Enhancement of ethylene formation by selenoamino acids,” Plant Physiology, vol. 62, 1978, pp. 397-401.
F. J. A. Pinheiro, R. S. Barros, T. G. Coelho and B. M. L. Souza, “Breaking dormancy of Stylosanthes humilis seeds with sele-nium compounds,” Seed Science Research, Vol. 18, 2008, pp. 47-53.
R. Feng, C. Wei, S. Tu, X. Sun, “Interactive ef-fects of selenium and arsenic on their uptake by Pteris vittata L. under hydroponic conditions”, Environmental and Experimen-tal Botany, Vol. 65, 2009, pp. 363-368.
R. J Williams, R. Reid, R. Schultze-Kraft, N. M. Souza Costa and B. D. Thomas, “Natural distribution of Stylosanthes,” In: H. M. Stace and L. A. Edye, Eds, The Biology and Agronomy of Stylosanthes, Academic Press, Sydney, 1984, pp. 73-110.
C. J. Gardner, “The Dynamics of Stylosanthes Pastures”, In; H. M. Stace and L.A. Edye, Eds, The Biology and Agronomy of Stylosanthes, Academic Press, Sydney, 1984, pp. 333-357.
A. F Rangel, M. Mobin, I. M. Rao and W. J Horst, “Proton toxicity inter-feres with the screening of common bean (Phaseolus vulgaris L.) genotypes for aluminium resistance in nutrient solution,” Journal of Plant Nutrition and Soil Science, Vol. 168, 2005, pp. 607-616.
K. H. Jones and J. A. Senft, “An improved method to determine cell viability by simultaneous staining with fluorescein diacetate-propidium iodide,” Journal of His-tochemistry and Cytochemistry, Vol. 33, 1985, pp. 77-79.
D. L. Jones, E. B. Blancaflor, L. V. Kochian and S. Gilroy, “Spatial coordination of aluminium uptake, production of reactive oxygen species, callose production and wall rigidi-fication in maize root plant”. Plant Cell and Environment, Vol. 29, 2008, pp. 1309-1318.
S. Lobréaux, S. Thoiron and J.-F. Briat, “Induction of ferritin synthesis in maize leaves by an iron-mediated oxidative stress,” The Plant Journal, vol. 8, 1995, pp. 443-449.
C. F. Babbs, J. A. Phan and R.C. Coolbaugh, “Lethal hydrogen radical production in paraquat-treated plants”, Plant Physiogy, Vol. 90, 1989, pp. 1267-1270.
C. H. Foyer, M. Lelandais and K. J. Kunert, “Photooxidative stress in plants”, Physiologia Plantarum, Vol. 92, 1994, pp. 696-717.
T. Xue, H. Hartikainen and V. Piironen, “Antioxidative and growth-promoting effect of sele-nium on senescing lettuce,” Plant and Soil, Vol. 237, 2001, pp. 55-61.
R. S. Barros, A. W. P. Freitas, “Selenomethionine as a dormancy-breaking agent in seeds of Stylosanthes humi-lis”. Acta Physiologicae Plantarum, Vol. 23, 2001, pp. 279-284.
D. van Hoewyk, H. Takahashi, E. Inoue, A. Hess, M. Tamaski and E. A. H. Pilon-Smits, “Transcriptome analyses give insights into selenium-stress responses and sele-nium tolerance mechanisms in Arabidopsis,” Physiologia Plantarum, Vol. 132, 2008, pp. 236-256.
P. Sun, Q.-Y. Tian, M. G. Zhao, X. Y. Dai, J. H. Huang, L. H. Li et al., “Aluminum-induced ethylene production is associated with inhibition of root elongation in Lotus japonicus L,” Plant and Cell Physiology, Vol. 48, 2007, pp. 1229-1235.
N. Mas-sot, B. Nicander, J. Barcelo, C. H. Poschenrieder and E. Till-berg, “A rapid increase in cytokinin levels of root growth in bean seedlings (Phaseolus vulgaris L),” Plant Growth Regula-tion, Vol. 37, 2002, pp. 105-112.
P. Sun, Q.-Y. Tian, J. Chan and W.-H. Zhang, “Aluminium-induced inhibition of root elongation in Arabidopsis is mediated by ethylene and auxin,” Journal of Experimental Botany, Vol. 2, 2010, pp. 347-356.