镉在草地早熟禾中的分布和化学形态研究

Study on Distribution and Chemical Forms of Cd in Poa pratensis

为探究草地早熟禾(Poa pratensis L.)对重金属镉(Cadmium,Cd)的分配和耐受机制,以草地早熟禾耐Cd品种‘午夜’(‘Midnight’,M)和Cd敏感品种‘橄榄球2号’(‘Rugby II’,R)为试验材料,在水培条件下施加600μmol·L^(-1)Cd胁迫,研究Cd在草地早熟禾中的组织分布、亚细胞分布及化学形态。结果表明,与R品种相比,Cd胁迫下M品种叶片失绿较少,生长抑制较小;表皮+叶肉、维管束及根表皮+皮层中的Cd含量显著低于R品种;另外,根系可溶部分Cd含量高于R品种。进一步分析发现,R品种含有更多毒性较高的无机态Cd及果胶和蛋白质结合态Cd,而M品种水溶性有机酸结合的Cd在根表皮+皮层、中柱等组织中含量较多,草酸盐结合的Cd在根系中柱含量显著高于R品种。因此,M品种通过减少Cd吸收、增加液泡区隔化、增加有机酸盐结合的Cd并降低Cd向地上的长距离运输来增强对Cd的抗性。

To investigate the Cd distribution and tolerance mechanisms in Kentucky bluegrass,the Cd-tolerant and Cd-sensitive cultivars named Midnight(M)and Rugby(R)were used as the experimental materials.The distribution and chemical forms of Cd in tissue and subcellular at a hydroponic culture condition were studied under 600μmol·L^(-1) Cd stress.The results showed that M genotype had less leaf chlorosis and growth inhibition under Cd stress compared with R genotype.The Cd concentrations in epidermis+mesophyll,vascular bundle,and rhizodermis+cortex of M genotype were significantly lower than that of R genotype.In addition,the soluble Cd concentrations in roots of M genotype were higher than that of R genotype.The inorganic Cd,pectinate and protein bound Cd in R genotype were higher than those in M genotype,while the M genotype had higher concentration of water-soluble organic acid bound Cd in rhizodermis+cortex and stele,and oxalate-bound Cd in stele.Therefore,the M genotype increased Cd tolerance by decreasing the absorption of Cd,increasing the vacuolar compartmentation,organic acid bound Cd,and decreasing the long-distance translocation of Cd from roots to shoots.