Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.
Ecotoxicol Environ Saf. 2020 Feb;189:109942. doi: 10.1016/j.ecoenv.2019.109942. Epub 2019 Nov 20.
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.
虽然硒代蛋氨酸(SeMet)的化学特性与蛋氨酸(Met)相似,但它在刺激植物组织产生乙烯的能力上的生理活性显然不同。由于硒通过改变乙烯的产生来改变水稻幼苗的根系结构,因此研究 SeMet 和 Met 对水稻生长的影响将是揭示硒毒性基础因素的重要一步。在这里,我们报告 SeMet 增加了活性氧(ROS)的浓度,抑制了生长素的产生并增加了水稻幼苗中的乙烯生成。SeMet 对幼苗的影响是通过抑制编码生长素运输和细胞扩展蛋白的转录本的丰度来介导的。此外,SeMet 导致幼苗呼吸作用增加,这与有机酸消耗呈正相关,与糖消耗呈负相关,从而降低了幼苗生长。与 SeMet 处理相反,Met 不影响 ROS 产生、激素生物合成和幼苗生长,表明这是一种独特的硒效应。单线态氧清除剂 1,4-二氮杂二环辛烷克服了 SeMet 对幼苗生长的抑制作用。我们的研究结果表明 SeMet 对水稻幼苗具有植物毒性作用,并揭示了活性氧、激素平衡和碳可用性之间的关系,这关系到生长反应的调控。