Selenomethionine induces oxidative stress and modifies growth in rice (Oryza sativa L.) seedlings through effects on hormone biosynthesis and primary metabolism

• Published in: Ecotoxicology and environmental safety Vol. 189; p. 109942
• Main Authors: Malheiros, Rafael S.P., Gonçalves, Fabrício C.M., Brito, Fred A.L., Zsögön, Agustín, Ribeiro, Dimas M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.02.2020
• Subjects: Antioxidants - metabolism; Ethylenes - biosynthesis; Growth inhibition; Hormonal regulation; Indoleacetic Acids - metabolism; Methionine - pharmacology; Oryza - drug effects; Oryza - growth & development; Oryza - metabolism; Oxidative Stress; Plant Growth Regulators - biosynthesis; Primary metabolism; Reactive oxygen species; Reactive Oxygen Species - metabolism; Seedlings - drug effects; Seedlings - growth & development; Seedlings - metabolism; Selenium; Selenomethionine - toxicity; ACC; Reactive oxygen species; IAA; APX; SOD; SeMet; MDA; Growth inhibition; DABCO; GPX; Hormonal regulation; CAT; ROS; Primary metabolism; Selenium; Met
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2019.109942

Although the chemical characteristics of selenomethionine (SeMet) are similar to those of methionine (Met), the physiological activity of SeMet apparently differs in its ability to stimulate ethylene production in plant tissues. Since selenium alters root architecture of rice seedlings by modifying ethylene production, the investigation of the effect of SeMet and Met on rice growth would be a step forward towards unraveling factors that underlie selenium toxicity. Here, we report that SeMet increased concentrations of reactive oxygen species (ROS), inhibiting auxin and increasing ethylene production in rice seedlings. The effect of SeMet on seedlings was mediated by the inhibition of the abundance of transcripts encoding auxin transport and cell expansion proteins. Moreover, SeMet led to increased seedling respiration, which was positively correlated with organic acids consumption, but negatively with sugars consumption, thereby decreasing seedling growth. In contrast with SeMet treatment, Met did not affect ROS production, hormone biosynthesis and seedling growth, indicating an exclusive selenium effect. The singlet oxygen scavenger, 1,4-diazabicyclooctane, overrode the repressive effect of SeMet in seedling growth. Our results demonstrate a phytotoxic effect of SeMet for rice seedlings and reveal a relationship between reactive oxygen species, hormone homeostasis and carbon availability, which regulates growth responses. •SeMet at low concentration inhibits growth of rice seedlings.•SeMet at low concentration stimulates reactive oxygen species in rice seedlings.•SeMet increases ethylene production and reduces auxin biosynthesis by rice seedlings.•SeMet modify the energy metabolism in rice seedlings.