Net cadmium flux and accumulation reveal tissue-specific oxidative stress and detoxification in Populus x canescens
Net cadmium flux and accumulation reveal tissue-specific oxidative stress and detoxification in Populus x canescens
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DOI：
10.1111/j.1399-3054.2011.01487.x
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发表时间：
2011-09-01
影响因子：
6.4
通讯作者：
Luo, Zhi-Bin
中科院分区：
文献类型：
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作者：
He, Jiali;Qin, Jingjing;Luo, Zhi-Bin
为了表征根际Cd 2+通量的动态，并研究镉（Cd）在根、木材、树皮和叶中的植物内部分配与能量代谢、活性氧簇（ROS）形成和抗氧化剂的关系，将黑杨幼苗暴露于0或50 μ M的CdSO 4中在营养液中长达20天。Cd处理24 h后，尽管根中Cd 2+净流入量逐渐减少，但根尖仍有较强的Cd 2+净流入量。Cd在根中有大量积累。镉离子通过木质部上传到叶片，并进一步运输到韧皮部，检测到显着的积累。镉的积累导致光合碳同化减少，但不消耗可溶性碳水化合物。增加的活性氧水平存在于所有组织中，除了树皮的镉暴露杨树。为了对抗Cd诱导的超氧化物和过氧化氢，P. x canescens似乎主要依赖于可溶性酚类化合物的形成，因为这些化合物在树皮中的积累最高，在木材中的积累最低。其他潜在的自由基清除剂，如脯氨酸，糖醇和抗氧化酶表现出组织和暴露时间特异性镉的反应。这些结果表明一个复杂的模式的内部镉分配在P. x canescens导致更高的ROS应力在木材比树皮和中间响应根和叶，可能是因为这些组织的生产能力不同的保护酚类化合物。
To characterize the dynamics of Cd2+ flux in the rhizosphere and to study cadmium (Cd) plant-internal partitioning in roots, wood, bark and leaves in relation to energy metabolism, reactive oxygen species (ROS) formation and antioxidants, Populus x canescens plantlets were exposed to either 0 or 50 mu M CdSO4 for up to 20 days in the nutrient solution. A strong net Cd2+ influx in root apex was observed after Cd exposure for 24 h, even if net Cd2+ influx decreased gradually in roots. A large amount of Cd was accumulated in roots. Cd ions were uploaded via the xylem to leaves and further transported to the phloem where significant accumulation was detected. Cd accumulation led to decreased photosynthetic carbon assimilation but not to the depletion in soluble carbohydrates. Increased levels of ROS were present in all tissues, except the bark of Cd-exposed poplars. To combat Cd-induced superoxide and hydrogen peroxide, P. x canescens appeared to rely mainly on the formation of soluble phenolics as these compounds showed the highest accumulation in the bark and the lowest in wood. Other potential radical scavengers such as proline, sugar alcohols and antioxidant enzymes showed tissue-and exposure time-specific responses to Cd. These results indicate a complex pattern of internal Cd allocation in P. x canescens resulting in higher ROS stress in wood than in bark and intermediate responses in roots and leaves, probably because of differential capacities of these tissues for the production of protective phenolic compounds.