Department of Plant Productions, Agricultural Faculty of Bardsir, Shahid Bahonar University of Kerman, 7841753693, Iran.
Department of Ecology, Environment and Plant Sciences, Stockholm University, S-10691 Stockholm, Sweden.
Ecotoxicol Environ Saf. 2019 Apr 30;171:321-328. doi: 10.1016/j.ecoenv.2018.12.052. Epub 2019 Jan 4.
Cadmium (Cd) can stress plants by affecting various physiological functions. Cd stress-response mechanisms were investigated in two genotypes of domesticated safflower (Carthamus tinctorius) and a population of wild safflower (Carthamus oxycantous) to explore potential differences in tolerance mechanisms of these species. A hydroponic experiment was conducted with 6-day-old safflower plants. Genotypes AC-Sterling (tolerant) and Saffire (semi-tolerant) from C. tinctorius, and Arak (sensitive) a population from C. oxycantouswere subjected to three concentrations of Cd (i.e., 0, 1, and 20 µM CdCl). Genotypic differences were detected in Cdtolerance index, Cd concentration in shoots and roots, Cd translocation to shoots, Cd bound to cell walls, superoxide dismutase (SOD) activity, lipid peroxidation, and phytochelatins accumulation in safflower plants upon exposure to CdCl. Results indicate that genotypic differences were more obvious in the presence of low (i.e., 1 µM) rather than high (i.e., 20 µM) CdCl concentrations. Comparing genotypes, root and shoot Cd accumulation was highest in the semi-tolerant genotype. Cadmium translocation to shoots was increased with increasing tolerance. The percentage of Cd bound to root cell walls was higher in the tolerant genotype, but only with low CdCl addition. Furthermore, in the tolerant genotype, SOD activity was lowest in both roots and shoots with low CdCl addition but highest with high CdCl addition, while the opposite was found for phytochelatins. Lipid peroxidation was decreased with Cd tolerance at both CdCl concentrations. We conclude that safflower relies mainly on binding Cd to the cell walls and the formation of phytochelatins in root and shoot tissues, in order to handle the Cd stress, evidenced by lessening Cd-induced lipid peroxidation.
镉 (Cd) 可以通过影响各种生理功能来胁迫植物。本研究以两种栽培红花（Carthamus tinctorius）基因型和野生红花（Carthamus oxycantous）群体为材料，研究 Cd 胁迫响应机制，以探讨这些物种的耐受机制的潜在差异。采用水培试验，以 6 天大的红花植株为材料，用 0、1 和 20 μM CdCl2 处理三种浓度 Cd。在暴露于 CdCl2 时，检测红花植物的耐 Cd 指数、地上部和根部的 Cd 浓度、Cd 向地上部的转移、Cd 与细胞壁的结合、超氧化物歧化酶（SOD）活性、脂质过氧化和植物螯合肽的积累。结果表明，在低浓度（1 μM）CdCl2 存在时，基因型差异更为明显，而在高浓度（20 μM）CdCl2 存在时，基因型差异则不明显。与基因型相比，半耐受基因型的根和地上部 Cd 积累量最高。Cd 向地上部的转移随耐受程度的增加而增加。与细胞壁结合的 Cd 百分比在耐受基因型中较高，但仅在低 CdCl2 处理时才如此。此外，在耐受基因型中，SOD 活性在低 CdCl2 处理时在根和地上部均最低，但在高 CdCl2 处理时最高，而植物螯合肽则相反。在两种 CdCl2 浓度下，脂质过氧化都随着 Cd 耐受而降低。综上所述，红花主要通过将 Cd 与细胞壁结合以及在根和地上部组织中形成植物螯合肽来处理 Cd 胁迫，这表现为减轻 Cd 诱导的脂质过氧化。
