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

Nitrogen (N) speciation could influence the efficiency  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 affects 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.) affected by different NO3−/ NH4+ ratios under low-and-high Cd stress.

Results  showed that both N speciation and Cd stress affected 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 affect 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+ influxes at the root hair zone were inhibited with the  increasing NH4+-N ratios in absence or pretreatment with different  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 different 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.

Fig. 1. Effect of different NO3-/NH4+ ratios (A and B)  or pretreatment with different ratios of NO3-/NH4+ (C and D) on net Cd2+  influx at root hair zone by Non-invasive Micro-test Technology(NMT). Each  point represents the mean values of Cd2+ influx of six roots from six  individual plants during the time of 6th-10th minutes. Bars with  different letters mean significantly statistical differences 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)'.

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