Impaired leaf CO2 diffusion mediates Cd-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata.
Impaired leaf CO2 diffusion mediates Cd-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata.
复制标题
DOI：
10.1016/j.plaphy.2013.09.008
复制
发表时间：
2013-12
期刊：
影响因子：
--
通讯作者：
Lu Tang;Rong-rong Ying;D. Jiang;Xiao-wen Zeng;J. Morel;Ye-tao Tang;R. Qiu
中科院分区：
文献类型：
--
作者：
Lu Tang;Rong-rong Ying;D. Jiang;Xiao-wen Zeng;J. Morel;Ye-tao Tang;R. Qiu
采用光合作用限制分析法研究了Cd对Zn/Cd超积累植物野豌豆（Picrisdivaricata）光合作用的抑制机制。对光合作用的总限制（TL）从5 μM Cd时的0%增加到75 μM Cd时的68.8%。CO2扩散限制（DL）对TL的贡献最大，在3个高Cd处理中占TL的93-98%，而生化限制（BL）仅占TL的2-7%。显微成像显示，气孔密度和叶肉厚度显着降低，在三个最高的镉处理。与光合生物化学相关的叶绿素荧光参数（Fv/Fm、NPQ、ΦPSII和qP）不随Cd供应量的增加而显著降低。研究结果表明，叶片数的增加是镉胁迫下叉枝海棠光合作用受到抑制的主要原因，其原因可能与叶肉和气孔功能受到抑制有关。叶绿素荧光分析结果表明，Cd胁迫对叉枝海棠光合作用的影响不大，说明PSII反应中心不是Cd胁迫下叉枝海棠光合作用受抑制的主要靶点。
Mechanisms of cadmium (Cd)-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulatorPicrisdivaricatawere investigated using photosynthesis limitation analysis.P. divaricataseedlings were grown in nutrient solution containing 0, 5, 10, 25, 50, or 75 μM Cd for 2 weeks. Total limitations to photosynthesis (TL) increased from 0% at 5 μM Cd to 68.8% at 75 μM Cd. CO2diffusional limitation (DL) made the largest contribution toTL, accounting for 93–98% ofTLin the three highest Cd treatments, compared to just 2–7% ofTLattributable to biochemical limitation (BL). Microscopic imaging revealed significantly decreased stomatal density and mesophyll thickness in the three highest Cd treatments. Chlorophyll fluorescence parameters related to photosynthetic biochemistry (Fv/Fm, NPQ,ΦPSII, andqP) were not significantly decreased by increased Cd supply. Our results suggest that increasedDLin leaves is the main cause of Cd-induced inhibition of photosynthesis inP. divaricata, possibly due to suppressed function of mesophyll and stomata. Analysis of chlorophyll fluorescence showed that Cd supply had little effect on photochemistry parameters, suggesting that the PSII reaction centers are not a main target of Cd inhibition of photosynthesis inP. divaricata.