硅对镉胁迫下菜心微量元素吸收与转运的影响

Effects of Silicon on Uptake and Transport of the Trace Elements of Flowering Chinese Cabbage Exposed to Cadmium Stress

为探讨镉(Cd)胁迫下,施硅(Si)处理对植物体对微量元素吸收与转运的影响,采用营养液培养方式,研究了在低(1μmol·L^(-1))、高(5μmol·L^(-1))Cd胁迫下施Si处理对菜心(Brassica campestris L.ssp.chinensis var.utilis)地上部、根部微量元素铁(Fe)、锰(Mn)、铜(Cu)、锌(Zn)含量,根系质外体、共质体及细胞壁中微量元素含量分配和木质部中各微量元素浓度变化的影响。结果显示,(1)Cd胁迫下菜心地上部对微量元素的吸收均表现出"低促高抑"的趋势,根部吸收紊乱,施Si后,地上部Fe、Cu、Zn含量呈不同程度的增加趋势,但Mn含量降低;根部Fe、Cu、Zn含量在施Si后也普遍增加,但差异不显著,对Mn则表现出拮抗作用。(2)Cd胁迫破坏了根系质外体、共质体、细胞壁中微量元素分布平衡,施Si处理普遍提高根系共质体和细胞壁中Fe、Cu、Zn含量,同时降低了Mn含量,增大了共质体中各微量元素的分配比例。(3)施Si普提高了木质部中Fe、Cu、Zn的浓度,降低了Mn的浓度,缓解了Cd对木质液中微量元素运输的影响。结论:Cd胁迫下,施Si通过提升微量元素在根系共质体及共质体的再分配,增强木质部微量元素的转运能力及其在地上部的富集能力,维持了菜心在Cd胁迫下的微量元素平衡。

This research evaluated the effects of silicon (Si) application on the absorption and transport of the trace elements (Fe, Mn,Cu, Zn) within plants under cadmium (Cd) stress. Flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis) wasexposed to low (1 μmol·L-1) and high (5 μmol·L-1) Cd/Si treatments by nutrient solution culture experiments, and trace elementconcentrations in apoplast, symplast, cell walls, xylem and plant tissues (shoots and roots) were analyzed. Results showed that, (1)the trace element concentrations in shoots were enhanced by low Cd addition while showed the opposite trend in high Cd treatment.The application of Si could increase the concentrations of Fe, Cu and Zn in shoots, while decreased of Mn. (2) The addition of Cdcould influence the distribution of the trace elements in apoplast, symplast and cell walls of roots. While Si application could elevatethe distribution proportion of the trace elements in symplast and the concentrations of Fe, Cu and Zn in symplast and cell wall ofroots, while decreased the concentrations of Mn in these parts. (3) Si addition increased the concentrations of Fe, Cu and Zn in xylem,and decreased that of Mn, which indicated that Si could mitigate Cd stress in xylem loading process. These results reveal that Sicould alleviate Cd stress by enhancing root symplast uptake, xylem loading and shoot accumulation of trace elements in floweringChinese cabbage under Cd stress.