The role of root apoplastic barriers in cadmium translocation and accumulation in cultivars of rice (Oryza sativa L.) with different Cd-accumulating characteristics
The role of root apoplastic barriers in cadmium translocation and accumulation in cultivars of rice (Oryza sativa L.) with different Cd-accumulating characteristics
复制标题
根质外体屏障在不同镉积累特性水稻品种镉转运和积累中的作用
DOI：
10.1016/j.envpol.2020.114736
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发表时间：
2020
影响因子：
8.9
通讯作者：
Ye Zhihong
中科院分区：
文献类型：
--
作者：
Qi Xiaoli;Tam Nora Fung-yee;Li Wai Chin;Ye Zhihong
镉（Cd）从根向地上部的径向转运是影响水稻（Oryza sativa L.）水稻中Cd的质外体转运研究较少。本研究旨在探讨质外体障碍对水稻镉转运途径、水稻上部（地上部和籽粒）镉积累水平的影响及其可能机制。通过水培和土培试验，研究了不同镉积累特性水稻品种根系质外体屏障的发育、化学组成及其对旁路流的渗透性，并测定了镉在根中的定位。Cd在上部的积累量与根中的旁路流和木质部中的表观Cd浓度呈正相关，表明质外体途径可能在水稻Cd根-冠转运中起重要作用。质外体障碍沉积更接近根尖，并在低镉积累品种比高镉积累品种厚。Cd胁迫下，ZD 14（低Cd积累品种）木质素和木栓质含量的增加量和增加速率显著高于FYXZ（高Cd积累品种），表明Cd胁迫对ZD 14的胁迫屏障较强。在低Cd积累的品种中，较强和较早形成的屏障更有效地减少了旁路流，从而使更多的Cd在质外体转运过程中保留在根中。这是证实了本地化分析的镉在根横截面。这些结果表明，质外体障碍减少了Cd在水稻根-冠转运途径中的转运，从而降低了Cd在水稻植株上部的积累。旁通流可作为水稻低镉积累品种的快速筛选指标。
The radial translocation of cadmium (Cd) from the root to the shoot is one of the major processes affecting Cd accumulation in rice (Oryza sativaL.) grains, but few studies have focused on Cd apoplastic transport in rice. The aim of this study was to determine how apoplastic barriers affect Cd translocationviathe apoplastic pathway, Cd accumulation levels in upper parts (shoot and grains) of rice cultivars, and the possible mechanism involved. Hydroponic and soil pot trials were conducted to study the development and chemical constituents of apoplastic barriers and their permeability to bypass flow, and to determine Cd localization in the roots of rice cultivars with different Cd-accumulating characteristics. The Cd accumulation in upper parts was positively correlated with bypass flow in the root and the apparent Cd concentration in the xylem, indicating that the apoplastic pathway may play an important role in Cd root-shoot translocation in rice. Apoplastic barriers were deposited closer to the root tip and were thicker in low Cd-accumulating cultivars than in high Cd-accumulating cultivars. The amounts and rates of increase in lignin and suberin were significantly higher in ZD14 (a low Cd-accumulating cultivar) than in FYXZ (a high Cd-accumulating cultivar) under Cd stress, indicating that stronger barriers were induced by Cd in ZD14. The stronger and earlier formation of barriers in the low Cd-accumulating cultivar decreased bypass flow more efficiently, so that more Cd was retained in the root during apoplastic translocation. This was confirmed by localization analyses of Cd in root transverse sections. These results suggest that apoplastic barriers reduce Cd root-to-shoot translocationviathe apoplastic pathway, leading to lower Cd accumulation in the upper parts of rice plants. Bypass flow may have the potential to be used as a rapid screening indicator for low Cd-accumulating rice cultivars.