Abstract:

By analyzing the differences in cadmium uptake and distribution among various strains of introgression lines of Yuanjiang common wild rice, this study carried out a field experiment to examine the dynamic changes of cadmium, subcellular distribution, and cadmium content in different organs among four strains of Yuanjiang common wild rice (including two low cadmium lines and two high cadmium lines). The results showed the following pattern for Cd content in tissues of all the strains of Yuanjiang common wild rice: root>stem>leaf>husk>grain. Cd content in root, husk, and grain of high Cd lines was significantly higher than that of low Cd lines. The Cd content in roots of high Cd lines (GJ11, GJ110) was 24.2 mg∙kg^-1 and 22.4 mg∙kg^-1, respectively, twice as much as that of low Cd lines. The root/grain ratio of GJ11 and GJ110 was 43.21 and 32.94, respectively, much lower than that of GJ71 (67.5) and GJ91 (471). The dynamic changes of Cd content in roots of different strains were consistent during the whole growing periods. However, dynamic changes of Cd content between high and low Cd lines showed differences. Unlike the Cd content within high Cd lines, that in stems of GJ71 and GJ91 increased dramatically from the booting stage to the heading stage, and that in leaves increased at first and then dropped slowly from the filling stage to the maturing stage. The subcellular distribution of Cd in organs of four strains at the tillering stage and the filling stage showed that cell wall>soluable part>organelle, with the Cd content in the cell wall accounting for 39.47%-60.39% of the total. In general, the capacity of high cadmium lines to absorb and transport cadmium to grain was higher than that of low cadmium lines. There were also differences in Cd uptake and transport within low Cd lines. In particular, GJ91 transported a large amount of Cd to and stored it in stems and leaves to reduce the Cd content in the seed.

Key words: common wild rice, introgression lines, Cd, subcellular distribution, dynamic changes

摘要：

通过对元江普通野生稻渗入系中籽粒镉含量低和高株系间镉吸收及分布差异的分析,探讨渗入系低镉株系籽粒镉低积累的原因。采用大田试验,对2份低镉株系、2份高镉株系各器官中镉含量、总积累量、亚细胞镉分布及生育期各器官镉积累动态变化特征进行研究。结果表明,所有株系不同器官镉含量高低顺序为根>茎>叶>谷壳>籽粒。高镉株系（GJ11、GJ110）根、谷壳、籽粒Cd含量均显著高于低镉株系,高镉株系根部镉质量分数分别为24.2、22.4 mg∙kg^-1,几乎是低镉株系（GJ71、GJ91）的2倍。高镉株系（GJ11、GJ110）根与籽粒的镉含量比值分别是43.21和32.94,均低于低镉株系（GJ71、GJ91）的67.5和471。所有株系根部镉动态变化趋势一致,镉积累量均上升。然而,高镉株系与低镉株系茎和叶部镉积累量在孕穗期和灌浆期出现差异,并且在灌浆期后发生分化。所有株系分蘖期和灌浆期各器官镉含量亚细胞分布表现为细胞壁>可溶部分>细胞器,细胞壁Cd含量占总量的39.47%—60.39%。研究表明,高镉株系对镉的吸收及转运到籽粒的能力均高于低镉株系,低镉株系间对镉的吸收及转运同样存在差异,其中GJ91能将地上部的镉大量分配并储存在茎叶内,从而降低籽粒镉含量。

关键词: 普通野生稻, 渗入系, 镉, 亚细胞分布, 动态变化