HAL Id: hal-02797874
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Does nitrogen supply impact the cadmium fluxes to developing durum wheat (Triticum turgidum L. subsp.
durum) grains?
Bofang Yan, Christophe Nguyen, Oleg Pokrovsky, Jean-Yves Cornu
To cite this version:
Bofang Yan, Christophe Nguyen, Oleg Pokrovsky, Jean-Yves Cornu. Does nitrogen supply impact the cadmium fluxes to developing durum wheat (Triticum turgidum L. subsp. durum) grains?. 18. International Conference on Heavy Metals in the Environment, Sep 2016, Ghent, Belgium. 2016, �10.13140/RG.2.2.36031.71843�. �hal-02797874�
Harvest at maturity
1ISPA, INRA, Bordeaux Sciences Agro, Villenave d’Ornon, France 2GET, CNRS, Université de Toulouse, Toulouse, France
Does Nitrogen Supply Impact the Cadmium Fluxes to Developing Durum
Wheat (Triticum turgidum L. subsp. durum) Grains?
Bofang Yan
1, Oleg S. Pokrovsky
2, Christophe Nguyen
1and Jean-Yves Cornu
1Background
Materials
Hypothesis & Objectives
Results
Grain Cd Cd Remobilization N Remobilization Interrupted N supplyTo determine the quantitative importance of the two
origins of the grain Cd by using Cd isotopic tracing.
To determine whether the supply of N during grain filling
has an impact on the Cd remobilization and the level of Cd
in the grains.
bofang.yan@bordeaux.inra.fr
Cd fluxes in plant under
continuous N supply
during grain filling
Cd fluxes in plant under
interrupted N supply
during grain filling
Cd2+ was supplied after transplanting at low dose:
non-toxic, fixed at 100 nM, p(Cd2+) = 10.78 (to reproduce
the level of exposure to Cd found in pore water of contaminated agricultural soils [3]);
111Cd-enriched isotope labeling after anthesis until
maturity;
Two treatments: continuous or interrupted N supply
after anthesis until maturity;
Harvest 2 times: at anthesis, at maturity;
Five repetitions.
Conclusions
The remobilization process accounts for about half (50-60%) of the Cd in durum wheat grains.
The N supply after anthesis had no impact on the Cd fluxes into developing grains. Cd remobilization may thus be a senescence-independent process.
The low availability of N during grain filling period in the field may not affect the accumulation of Cd in durum wheat grain.
[1] Harris, N. S. et al. BMC Plant Biology (2013) 13:103; [3] Nolan, A. L. et al. Environmental science & technology (2003) 37(1), pp. 90-98.
[2] Maillard, A et al. Frontiers in plant science (2015) 6;
𝑸𝒔 𝑸𝒆𝒊 = 𝑴𝒔 𝑴𝒆𝒊 ∙ 𝑨111𝒆𝒊 𝑨114𝒔 ∙ 𝑹𝒎 − 𝑹𝒆𝒊 114 111 1 − 𝑹𝒎 × 𝑹𝒔 111 114
𝑸
𝒆𝒊=
𝟏
𝟏 +
𝑸
𝒔𝑸
𝒆𝒊×
𝑸
𝒕𝒐𝒕𝑸
𝒔=
𝑸
𝒕𝒐𝒕− 𝑸
𝒆𝒊The amount of Cd remobilized
The amount of
Cd derived from root uptake
Cd derived from
root uptake
Cd
Remobilized
Cadmium is a toxic, non-essential element. It can be accumulated in durum wheat grain to levels exceeding the international trade standards, which is threatening human health.
Cd imported into developing durum wheat grains originates from either direct uptake of Cd by roots or remobilization of Cd stored in vegetative organs. The remobilization of Cd has been shown to be quite limited when hydroponic plants are continuously well-supplied with nitrogen [1], while the availability of N is often low in field soils. N deficiency accelerates leaf senescence which often induces the remobilization processes [2]. So it is possible that, if Cd remobilization is a senescence-dependent process, the level of N supply might affect the fluxes of Cd to developing grains by its impact on plant senescence.
Consequently, it is necessary to quantify the relative contribution of the two pathways for grain Cd loading and to assess how their relative contributions may be impacted by the levels of N supply.
57%
of the grain N derived from
remobilization
100%
of the grain N derived from
remobilization
100nM Cd2+ 100nM 111Cd -N supply Harvest at anthesis GF-AAS ICP-MS Total Cd (Qtot) 114Cd/111Cd (R m) Grains Head structure
(Bracts & Rachis)
Leaves Stems
Roots
100nM 111Cd
+N supply
Durum wheat Cultivar: Sculptur;
Plants were trained to develop 4 tillers from the start of elongation;
Hydroponics: modified Hoagland’s nutrient solution at pH 6.0,
refreshed automatically;
𝑴𝒔and 𝑴𝒆𝒊: the molar weights of natural standard (s) Cd and enriched (ei) 111Cd isotope, respectively;
𝑨𝒆𝒊𝟏𝟏𝟏and 𝑨𝒔𝟏𝟏𝟒:the abundance of 111Cd in the labeled nutrient solution and is the natural abundance of 114Cd , respectively;
𝑹𝒎and 𝑹𝒆𝒊 𝟏𝟏𝟒 𝟏𝟏𝟏 : the 114Cd/111Cd ratio measured in the plant sample and in the labeled nutrient
solution , respectively
𝑹𝒔 𝟏𝟏𝟏 𝟏𝟏𝟒 : the natural ratio of 114Cd/111Cd.
Grain Elements conc. High N supply Low N supply N (%) 4.1a 4.4a Cd (μg/g) 1.3a 1.2a
85% of the Cd taken up during grain filling was allocated to vegetative organs.
Mean values with different letters are significantly different (P < 0.05)
The loss of Cd from roots was an unexpected observation.
Grain filling period
Grain filling period
Cd was remobilized from the stems to the grain.
+6.33 (±0.85)
0.82 (±0.13)
8.29 (±0.75)***
7.63 (±0.49)
5.73 (±1.21)**
9.12 (±0.95)
16.91 (±1.61)***
4.55 (±2.95)***
Roots
Stems
Leaves
Head Structure
Grains
3.07 (±0.15)
3.44 (±2.23)
3.15 (±0.93)
7.41 (±1.02)
1.87 (±2.14)
3.26 (±0.91)6.54 (±0.58)
23.09 (±2.69)
2.16 (±3.81)
48% Root uptake 52% Remobili-zationat Anthesis:
40.66 (±3.53) μg
at Maturity:
41.81 (±4.77) μg
Whole plant
amount of Cd
3.90 (±0.89)
3.57 (±0.25)
20.97 (±4.56) μg
19.81 (±3.64) μg
About half of the grain Cd was remobilized from the vegetative storage of Cd within plant . No significant difference in the cadmium fluxes in plant was observed when the level of N supply changed during grain filling. The level of grain N
wasn’t impacted by the interrupted N supply during grain filling thanks to the high efficiency of N remobilization. Plant Senescence Continuous N supply
The plants were separated into: Cd uptake positive effects negative effects
?
?%
Cd2+ +N 111Cd2+ 111Cd2+ Cd2+ +N -N Cd2+ +N+4.93 (±1.88)
0.82 (±0.13)
9.39 (±1.63)***
7.63 (±0.49)
4.05 (±1.10)***
9.12 (±0.95)
17.03 (±2.37)***
23.09 (±2.69)
2.86 (±0.90)***
Roots
Stems
Leaves
Head structure
Grains
15.31 (±6.43) μg
2.05 (±1.28)
1.96 (±0.68)
1.88 (±1.08)
5.69 (±2.35)
3.70 (±1.84)
4.85 (±1.50)
2.88 (±0.68)
4.48 (±3.59)
6.95 (±0.34)
17.71 (±4.02) μg
42% Root uptake 58% Remobili-zationat Anthesis:
40.66 (±3.53) μg
at Maturity:
38.27 (±6.77) μg
Whole plant
amount of Cd
3.72 (±1.30)
The % of remobilized Cd in the grain was higher but not statisticallysignificant (P>0.05) than that under continuous N supply.
The N supply after anthesis had no impact on the concentration of Cd in the grain.
