EEB：广东农科院丨提升铵营养有助于抑制水稻镉积累?

期刊：Environmental and Experimental Botany（EEB）

主题：提升铵营养有助于抑制水稻镉积累

标题：Increasing ammonium nutrition as a strategy for inhibition of cadmium uptake and xylem transport in rice (Oryza sativa L.) exposed to cadmium stress

影响因子：3.666

检测指标：Cd2+流速

检测部位：距根尖700μm

作者：广东农科院王旭、王富华、吴志超

英文摘要

Nitrogen (N) speciation could in?uence the e?ciency of Cd accumulation by plants grown in Cd-contaminated areas. However, limited information has been reported on how the application of N speciation to rice a?ects the Cd accumulation. Here, we investigated the physiological and genetic mechanisms involved in Cd uptake by roots, xylem translocation and subsequent Cd accumulation in rice (Oryza sativa L.) a?ected by di?erent NO3?/ NH4+ ratios under low-and-high Cd stress.
 
Results showed that both N speciation and Cd stress a?ected plant growth, with high NH4+-N ratios treatments having higher tissue biomass, and high Cd treatment reducing tissue biomass. The Cd concentrations in shoots and roots were reduced with the increasing NH4+-N ratios (except for the full NO3?-N treatment), but did not a?ect the Cd translocation factor (TF). The total Cd accumulation of the whole plant were also reduced with the high NH4+-N ratios (NO3?/NH4+, 1:2 and 0:1) on the low Cd treatment due to the decline both in the Cd accumulation of shoots and roots.
 
A Non-invasive Micro-test Technology (NMT) showed that the net Cd2+ in?uxes at the root hair zone were inhibited with the increasing NH4+-N ratios in absence or pretreatment with di?erent NO3?/NH4+ ratios. Additionally, the Cd concentrations in xylem sap were also displayed a decline trend with the increasing NH4+-N ratios under two dose Cd treatments.Furthermore, the gene expression related to Cd uptake (OsIRT1 and OsNRAPM5) and transport (OsHMA2) in roots showed the familiar tendencies with those of Cd uptake and transport at the physiological level treated with di?erent NO3?/NH4+ ratios under two dose Cd treatments.

It is concluded that increasing ammonium nutrition contributes to the inhibition of Cd uptake, xylem transport and subsequent accumulation in rice.

中文摘要（谷歌机翻）

氮（N）物种形成可能影响镉污染地区生长的植物对Cd积累的影响。然而，关于如何将N形态应用于水稻以影响Cd积累的报道有限。在这里，我们研究了在低和高Cd胁迫下由不同NO3-/NH4+比例影响的水稻（Oryza sativa L.）根系吸收Cd，木质部易位和随后Cd积累所涉及的生理和遗传机制。
 
结果表明，N形态和Cd胁迫均影响植物生长，高NH4+-N比处理具有较高的组织生物量，高Cd处理降低组织生物量。随着NH4+-N比值的增加，芽和根中的Cd浓度降低（除了完全的NO3-N处理），但不影响Cd转运因子（TF）。由于芽和根中Cd积累量的下降，低Cd处理的NH4+-N比值（NO3-/NH4+，1：2和0：1）也降低了整株植物的总Cd积累量。
 
非损伤微测技术（NMT）显示，在不存在或预处理不同的NO3-/NH4+比率时，NH4+ -N比率增加时，根毛区的流体中的净Cd2+受到抑制。此外，在两剂Cd处理下，随着NH4+-N比值的增加，木质部汁液中的Cd浓度也呈下降趋势。此外，与Cd吸收（OsIRT1和OsNRAPM5）和转运（OsHMA2）相关的基因表达显示了在两种剂量Cd处理下用不同的NO3-/NH4+比率处理的生理水平的Cd摄取和转运的熟悉趋势。
 
结论是，增加铵营养有助于抑制水稻的Cd吸收，木质部运输和随后的积累。

Fig. 1. E?ect of di?erent NO3-/NH4+ ratios (A and B) or pretreatment with di?erent ratios of NO3-/NH4+ (C and D) on net Cd2+ in?ux at root hair zone by Non-invasive Micro-test Technology(NMT). Each point represents the mean values of Cd2+ in?ux of six roots from six individual plants during the time of 6th-10th minutes. Bars with di?erent letters mean signi?cantly statistical di?erences followed by one-way ANOVA analysis (LSD test, P < 0.05, n=6). 'preCK' indicates 'pretreatment of the rice seedlings with NO3-/NH4+ (1:1)'.