不同水稻品种对镉积累的差异及其与镉亚细胞分布的关系

采用土培试验,以籽粒Cd低积累水稻品种(越冬稻和R1088)和籽粒Cd高积累水稻品种(IR34582和太粳558)为试验材料,研究成熟期水稻在Cd0(不加Cd)、Cd5(5 mg·kg~(-1))和Cd25(25 mg·kg~(-1))胁迫下,Cd在水稻各组织中的积累差异及其与Cd亚细胞分布的关系,为培育Cd低积累水稻品种和水稻安全生产提供科学依据。结果表明:(1) Cd胁迫下,约65%～83%的Cd积累于根系,低积累品种根系Cd含量显著高于高积累品种,而地上部却相反;(2)高积累品种往地上部转运Cd的效率以及地上部各组织往籽粒转运Cd的效率均显著高于低积累品种;(3) Cd胁迫下,低积累品种根中细胞壁(F1)、细胞器(F2)、细胞膜(F3)和可溶部分(F4)中Cd含量显著高于高积累品种,而茎、叶鞘和叶中却相反;(4)低积累品种根和茎中F1中Cd分配比例均显著高于高积累品种,而F4中Cd分配比例却相反;在叶鞘和叶中,F1、F4中Cd分配比例在不同品种之间无显著差异。(5) Cd胁迫下,TF_(根-茎)和TF_(茎-糙米)均与F1中Cd分配比例成显著负相关关系,而与F4中Cd分配比例成显著正相关关系。综上,高积累品种往地上部转运Cd的能力强于低积累品种;低积累品种根和茎中细胞壁限制了Cd的迁移;而高积累品种根和茎中可溶部分在Cd从根部向上以及从茎向籽粒转运过程中起着重要作用。

Cadmium Accumulation in Different Rice Varieties and Its Relationship with Subcellular Distribution of Cadmium

In order to provide scientific basis for breeding Cd low accumulation rice varieties and rice safety production, here the characteristics of accumulation difference of Cd in rice tissues and its relationship with Cd subcellular distribution were studied in a soil pot experiment. The experiments were conducted on low Cd accumulation rice varieties (overwintering rice and R1088) and high Cd accumulation rice varieties (IR34582 and Taijing 558) with three different cadmium treatments (0, 5 and 25 mg kg^-1). Here are the results, (1) About 65%~83% of Cd concentrated on roots under Cd stress, and the Cd content of low accumulation varieties in roots was significantly higher than that in high accumulation varieties, but the trend was opposite in the aerial parts. (2) The efficiency of Cd transportation from root to the aerial parts and then to brown rice was significantly higher in the high accumulation varieties than that in the low accumulation varieties. (3) The Cd contents of cell wall (F1), organelle (F2), cell membrane (F3) and soluble part (F4) in roots of low accumulation cultivars were significantly higher than those of high accumulation cultivars under cadmium stress, but the opposite trend was found in stems, leaf sheaths and leaves. (4) The proportion of F1-Cd distribution in the root and shoots of low accumulation cultivars was significantly higher than that of high accumulation cultivars, but the proportion of F4-Cd was opposite, and there was no significant difference in F1- and F4-Cd distribution in leaf and sheath among different varieties. (5) TF_root-stem and TF_{stem-brown rice} were negatively correlated with F1-Cd distribution, but positively correlated with F4-Cd distribution ratio. In summary, as for the ability of transporting Cd from root to the ground, high accumulation varieties were stronger than low accumulation varieties. Cell wall restricted the migration of Cd in low accumulation varieties'' roots and stems. Soluble fraction played an important role in the transportation of Cd from root to stem in high accumulation cultivars'' roots and shoots.