Department of Plant Physiology and Molecular Plant Biology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
OMICS. 2011 Nov;15(11):811-8. doi: 10.1089/omi.2011.0078. Epub 2011 Oct 19.
Cadmium is a toxic heavy metal causing iron deficiency in the shoot and light sensitivity of photosynthetic tissues that leads to decreased photosynthetic performance and biomass production. Light intensity had strong impact on both photosynthetic activity and metal accumulation of cadmium-treated plants. At elevated irradiation, cadmium accumulation increased due to the higher dry mass of plants, but its allocation hardly changed. A considerable amount of iron accumulated in the roots, and iron concentration was higher in leaves developed at moderate rather than low irradiation. At the same time, the higher the irradiation the lower the maximal photochemical quantum efficiency. The decreased photochemical efficiency, however, started to recover after a week of Cd treatment at moderate light without substantial change in metal concentrations but following the accumulation of green fluorescent compounds. Both cadmium treatment and higher light caused the accumulation of flavonoids in leaf mesophyll vacuoles/chloroplasts, but accumulation of flavonols, fluorescing at 510 nm, was characteristic to cadmium stress. Therefore, flavonoids, which may act by scavenging reactive radicals, chelating Cd, and shielding against excess irradiation, play an important part in Cd stress tolerance of Populus, and may have special impact on its phytoremediation capacity.
镉是一种有毒的重金属，它会导致植物地上部分缺铁和对光合组织的光敏感性，从而降低光合作用性能和生物量的产生。光照强度对镉处理植物的光合作用活性和金属积累都有强烈的影响。在高辐射下，由于植物干物质的增加，镉的积累增加，但分配几乎不变。大量的铁在根部积累，在中等而不是低辐射下发育的叶片中铁浓度更高。同时，光照越强，最大光化学量子效率越低。然而，在中等光照下进行 Cd 处理一周后，光化学效率的降低开始恢复，而金属浓度没有实质性变化，但绿色荧光化合物的积累却在继续。镉处理和高光都会导致叶肉液泡/叶绿体中类黄酮的积累，但积累的类黄酮在 510nm 处发荧光，这是镉胁迫的特征。因此，类黄酮可能通过清除活性自由基、螯合 Cd 和屏蔽过量辐射来发挥作用，它们在杨树对 Cd 胁迫的耐受性中起着重要作用，并可能对其植物修复能力有特殊影响。
