Department of Plant Biochemistry and Toxicology, Institute of Biology, University of Bialystok, Swierkowa 20 B, 15-950 Bialystok, Poland.
Arch Environ Contam Toxicol. 2011 Apr;60(3):406-16. doi: 10.1007/s00244-010-9551-0. Epub 2010 Jun 4.
Brassinosteroids play a significant role in the amelioration of various abiotic and biotic stresses. In order to elaborate their roles in plants subjected to heavy metals stress, Chlorella vulgaris cultures treated with 10(-8) M brassinolide (BL) were exposed to 10(-6)-10(-4) M heavy metals (cadmium, lead and copper) application. Under heavy metals stress, the growth and chemical composition (chlorophyll, monosaccharides, and protein content) have been decreased during the first 48 h of cultivation. The inhibitory effect of heavy metals on C. vulgaris cultures was arranged in the following order: copper > lead > cadmium. C. vulgaris cultures treated with BL in the absence or presence of heavy metals showed no differences in the endogenous level of BL. On the other hand, treatment with heavy metals results in BL level very similar to that of control cell cultures. These results suggest that the activation of brassinosteroids biosynthesis, via an increase of endogenous BL, is not essential for the growth and development of C. vulgaris cells in response to heavy metals stress. Simultaneously, BL enhanced the content of indole-3-acetic acid, zeatin, and abscisic acid in cultures treated with heavy metals. Levels per cell of chlorophylls, protein, and monosaccharides are all increased by BL treatment when compared to nontreated control cells. Application of BL to C. vulgaris cultures reduced the accumulation of heavy metals stress on growth, prevented chlorophyll, monosaccharides, and protein loss, and increased phytochelatins content. The arrested growth of C. vulgaris cells treated with heavy metals was restored by the coapplication of BL. It suggested that BL overcame the inhibitory effect of heavy metals. From these results, it can be concluded that BL plays the positive role in the alleviation of heavy metals stress.
油菜素内酯在改善各种非生物和生物胁迫方面发挥着重要作用。为了详细阐述其在植物重金属胁迫下的作用，用 10(-8) M 油菜素内酯 (BL) 处理的小球藻培养物暴露于 10(-6)-10(-4) M 重金属（镉、铅和铜）应用中。在重金属胁迫下，培养的前 48 小时内，生长和化学成分（叶绿素、单糖和蛋白质含量）下降。重金属对 C. vulgaris 培养物的抑制作用按以下顺序排列：铜>铅>镉。在存在或不存在重金属的情况下用 BL 处理的 C. vulgaris 培养物在 BL 的内源性水平上没有差异。另一方面，重金属处理导致 BL 水平与对照细胞培养物非常相似。这些结果表明，油菜素内酯生物合成的激活，通过增加内源性 BL，对于 C. vulgaris 细胞在重金属胁迫下的生长和发育不是必需的。同时，BL 增强了在重金属处理的培养物中吲哚-3-乙酸、玉米素和脱落酸的含量。与未处理的对照细胞相比，BL 处理增加了细胞内叶绿素、蛋白质和单糖的含量。BL 应用于 C. vulgaris 培养物可减少重金属胁迫对生长的积累，防止叶绿素、单糖和蛋白质的损失，并增加植物螯合肽的含量。重金属处理的 C. vulgaris 细胞的生长停滞通过 BL 的共同应用得到恢复。这表明 BL 克服了重金属的抑制作用。从这些结果可以得出结论，BL 在缓解重金属胁迫方面发挥着积极作用。
