不同硫浓度下叶面施硒对水稻幼苗镉的亚细胞分布及化学形态的影响

Effects of Selenium Foliar Spray on Subcellular Distribution and Chemical Forms of Cadmium in Rice Seedlings in Different Sulfur Concentrations

采用水培的方式,通过叶面喷施硒(Se),根部施加硫(S)与镉(Cd),研究了不同硫浓度下叶面施硒对水稻幼苗体内Cd的亚细胞分布和化学形态的影响。结果表明,在不同处理条件下,细胞壁组分所占比例均为Cd10>Cd1(Cd10代表浓度为10 mg·L-1的Cd,下同)。随着S的增加以及叶面施Se可溶性组分中Cd的比例有所升高,表明S与Se的供应能促进Cd向液泡转移。NaCl提取态所占比例趋势为S720>S48>S0、Se500>Se0,而乙醇和去离子水等活性较高的提取态所占比例有所下降,说明S的添加以及叶面施Se能够促使Cd向活性较低的提取态转移。然而相对于无S,在高浓度S情况下,施Se并未显著增加Cd在液泡中以及FNaCl提取态的比例,推测S与Se之间相互竞争,从而未产生协同作用。

Cadmium （Cd） is a toxic heavy metal to rice. Sulfur（S） and selenium （Se） may alleviate its toxicity by changing Cd distribution and species in rice seedlings. Here, we investigated the subcellular distribution and chemical forms of Cd in rice seedlings under different S concentrations and foliar-applied Se using hydroponic experiment. The proportion of Cd in cell wall was larger under 10 mg Cd· L-1 than under 1 mg Cd· L-1. As solution S and foliar-sprayed Se increased, soluble Cd increased while Cd in cell wall decreased, indicating the enhanced translocation of Cd to vacuole by the supply of S and Se. Also, the percentage of NaCl-extraction Cd fraction increased while that of ethanol-extractable Cd decreased with increasing supplies of S and Se, illustrating that the presence of S and Se could promote Cd transfer to less active forms. However, Se supply did not significantly increase Cd transfer into the vacuole and NaCl-extractable fraction under high S concentrations, implying competition between S and Se.