University of Bialystok, Faculty of Biology, Department of Plant Biology and Ecology, Ciolkowskiego 1J, 15-245, Bialystok, Poland.
University of Bialystok, Faculty of Chemistry, Department of Analytical and Inorganic Chemistry, Ciolkowskiego 1K, 15-245, Bialystok, Poland.
Sci Rep. 2020 Jun 23;10(1):10193. doi: 10.1038/s41598-020-67085-4.
Phytohormones, such as auxins and cytokinins, take part in the integration of growth control and stress response, but their role in algal adaptation to heavy metal remains to be elucidated. The current research indicated that lead (Pb), one of the most toxic metals in nature, causes severe depletion of endogenous cytokinins, auxins, and gibberellin and an increase in abscisic acid content in the green alga Acutodesmus obliquus. Exogenous auxins and cytokinins alleviate Pb toxicity through the regulation of the endogenous phytohormones' levels. Exogenously applied auxins provoked the coordinated activation metal tolerance mechanisms leading to the increase in phytochelatin synthase activity and accumulation of phytochelatins and their precursors, which are essential for Pb sequestration. On the other hand, phytochelatin synthesis decreased in algal cells treated with cytokinins. Significant changes in the levels of low molecular weight metabolites, mainly involved in metal chelation and glutathione synthesis pathway under the influence of phytohormones in algal cells growing in the presence of Pb stress, were observed. This is the first report showing that auxins and cytokinins are important regulatory factors in algal adaptation strategies to heavy metal stress based on thiol-mediated compounds and the maintenance of phytohormone homeostasis.
植物激素，如生长素和细胞分裂素，参与生长控制和应激反应的整合，但它们在藻类适应重金属方面的作用仍有待阐明。目前的研究表明，铅（Pb）是自然界中最有毒的金属之一，导致内源性细胞分裂素、生长素和赤霉素严重耗竭，以及绿藻斜生栅藻中脱落酸含量增加。外源生长素和细胞分裂素通过调节内源性植物激素水平来缓解 Pb 毒性。外源生长素引发了协调的金属耐受机制的激活，导致植酸酶合成酶活性增加，植酸和其前体积累，这对 Pb 螯合至关重要。另一方面，用细胞分裂素处理藻类细胞会导致植酸合成减少。在 Pb 胁迫下生长的藻类细胞中，观察到低分子质量代谢物水平的显著变化，这些代谢物主要涉及金属螯合和谷胱甘肽合成途径，受植物激素的影响。这是第一个表明生长素和细胞分裂素是基于巯基介导的化合物和植物激素内稳态维持的藻类适应重金属胁迫策略的重要调节因子的报告。
