nitrogenabsorption, translocation and fluxes in the … · nitrogenabsorption, translocation and...

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10th june 2011

Nitrogen absorption, translocation

and fluxes in the

Phelipanche ramosa / Brassica napus

interactionGaudin Z., Pouvreau J-B., Robins R.J., Delavault P., Simier

P.

Laboratoire de Biologie et Pathologie Végétale

IFR149 QUASAV, Université de Nantes, France

LBPV Université de NantesNitrogen Absorption, Translocation and Fluxes in the Phelipanche ramosa / Brassica napus Interaction- 2011.06.10

Agronomic context

Winter oilseed rape (WOSR): 1st protein-oil producing crop in Europe

(ONIDOL 2009)

Economic stability insured by an agronomicpolitic of diester production

Area1 481 000 ha

Yield37,7 q/ha

Harvest5 584 000 t

< 1 000 ha1 001 to 5 000 ha5 001 to 10 000 ha10 001 to 30 000 ha> 30 000 ha

France : − 1st European crop area (1 481 000 ha)− 2nd Europeen producer (5 584 000 metric tons)


Emergent agronomic problem

(Phelipanche ramosa on Brassica napus)Strongly infested districtInfested district

Phelipanche ramosa: recent adaptation to WOSR is a tremendous problem

� increasing infected area, mainly in the West



Phelipanche ramosa: recent adaptation to WOSR is a tremendous problem

� increasing infected area, mainly in the West

� Severe yield losses (especially for verysusceptibles genotypes)

Strongly infested districtInfested district



Control methods are inefficient or inadequate

� Urgent need of a better understanding of the interaction

Ex : solarisationNo totally resistant accessions in Brassica napus

New host plant, few information about interaction mechanisms:− mechanisms of resistance (cf. poster n° 038 Mathieu Gauthier)− host/parasite communication (cf. Philippe Simier oral presentation)


Predominant role of nitrogen for Brassica napus

High regime of N fertilization plays a major role in WOSR productivity

(Springtime WOSR fertilization)

Low nitrogen-use efficiency was demonstrated in WOSR(Malagoli & al. 2005, Annals of Botany 95 ; Rossato & al. 2001, Journal Exp. Bot. 52 (361) ; etc)

Resulting question:Impact of broomrape infestation on N-use efficiency for high susceptible and tolerantgenotypes? When N is available for broomrapes?How N is used by broomrapes?


Brassica napus / Phelipanche ramosaInteraction

� My PhD project focuses on nitrogenrole within host-parasite relationships

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My PhD work

1. Characterization of nitrogen allocation and fluxes within the P. ramosa / B. napus interaction:− B. napus susceptible and non-tolerant genotype− B. napus susceptible and tolerant genotype

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2. Characterization of nitrogen compounds transferred from the hostplant to the parasite and their metabolization in this parasite

3. Impact of fertilization on the capacity of B. napus to induce the germination of P. ramosa


My PhD work

1. Characterization of nitrogen allocation and fluxes within the P. ramosa / B. napus interaction:− B. napus susceptible and non-tolerant genotype− B. napus susceptible and tolerant genotype

2. Characterization of nitrogen compounds transferred from the hostplant to the parasite and their metabolization in this parasite

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3. Impact of fertilization on the capacity of B. napus to induce the germination of P. ramosa


Plant Material

ES Alienor (Seminis Company) chosen for its high susceptibility:— high number of attachments— early emergence of the parasite

Experimental set up


Nitrogen supply Methods

(CETIOM)

1 3 9 15 30 700

Vernalization

Starvation

Harvest time(Days after pulse)

Pulse (250µM K15NO315N 99%)

� Sample analysis for biomass determination and Isotopic Ratio Mass Spectrometry = IRMS (15N/14N)

(Samples: Roots, Hypocotyle, Stem, Leaves, Senescent leaves, Pods)

Experimental set up


Nitrogen supply Methods

(CETIOM)

1 3 9 15 30 700

P. ramosa

seeds (5mg) Vernalization

Starvation

Harvest time(Days After Pulse)

Pulse (250µM K15NO315N 99%)

(Samples : Roots, Hypocotyle, Stem, Leaves, Senescente leaves, Pods, Broomrapes)

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c

m

Stage 1, 2 and 3 Stage 4 Stage 5 Stage 6

� Sample analysis for biomass determination and Isotopic Ratio Mass Spectrometry = IRMS (15N/14N)

Experimental set up

(DAP)


A. Nitrogen allocation and fluxes within a P. ramosa / susceptible B. napus (ES Alienor) interaction

1. Characterization of nitrogen allocation and fluxes within the P. ramosa / B. napus interaction

Results


Unparasitized ES Alienor

− After root absorption, 15N is first translocated to leaves for assimilation(1st site of 15N allocation and assimilation (Morot-Gaudry & al. 2006 ; Rossato & al. 2001))

− Then assimilated 15N is relocated to stem and pods

− Following vernalization, leaves are the 1st compartment of biomass accumulation

Results

Cumulated Dry Weight (g) 15N amounts (g)


ES Alienor fluxes between 15 and 30 days

• 30 % of supplied 15N is remobilised from leaves to stem and pods.• An important part (~7 %) of 15N is lost in the senescent leaves

Roots :1,47 ± 0,71 %

Leaves :26,88 ± 1,79 %

Pods :7,16 ± 2,52 %

Senescent leaves : 7,36 ± 1,12 %

Stem :4,36 ± 1,27 %

Sources Sinks

Hypocotyle :0,11 ± 0,39 %

(% of supplied 15N ± SD)

Nitrogen-use inefficiency(concordant with Rossato & al. 2001

and Gomber & al. 2006)


Parasitized ES Alienor

− Broomrapes and leaves are the main compartments of biomass accumulation

Results

Cumulated Dry Weight (g) 15N amounts (g)

� The parasite doesn't absorb and assimilate mineral 15N� Then assimilated 15N is mainly relocated to broomrapes

− Infection has no impact on primary 15N absorption and assimilation in leaves


ES Alienor / P. ramosa fluxes between 15 and 30 days

Roots :0,46 ± 0,62 %

Leaves :19,57 ± 4,20 %

Broomrape :11,55 ± 5,12 %

Senescent leaves :5,40 ± 2,36 %

Sources Sinks

• 20 % of supplied 15N is remobilised from leaves to broomrapes.• An Important part (~7 %) of 15N is lost in the senescent leaves.• Stem and pod development is extremely reduced.

Hypocotyle :0,05 ± 0,12 %

Stem :0,06 ± 0,23 %

(% of supplied 15N ± SD)

Stem sink can not compete with broomrapes which pump the major part of 15N

Pods :0 ± 0 %


Conclusions

ES Alienor genotype

− High leaf N availability for attached broomrapes from the exit of vernalization on

− Early growth of the already attached broomrapes

− Important sink strength of the attached broomrapes

� Induction of an unbalanced source/sink competition in favor of broomrape


A. Nitrogen allocation and fluxes within a P. ramosa / susceptible B. napus genotype (ES Alienor) interaction

1. Characterization of nitrogen allocation and fluxes within the P. ramosa / B. napus interaction

Results

B. Impact of B. napus genotypes on nitrogen fluxes within P. ramosa / B. napus interaction


Results

� ES Alienor: leaf 15N flux to broomrape starts from the exit of vernalization on

� Shakira: leaf 15N flux to broomrape starts later on (15 days after vernalization)

15N fluxes (g per day)

ES Alienor Shakira

WOSR genotypes comparison (ES Alienor / Shakira)

This delay in broomrape growth allows Shakira to developp an important sink (stem)


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Our results raise major questions

How do we explain the difference in nitrogen remobilization between these two WOSR genotype:− difference in nitrogen metabolism ?− difference in hormonal balance ?

What are the molecular, metabolic and hormonal basis of the broomrape sink strength ?

What is the impact of the host genotype on those traits ?

Environmental politic aims to reduce nitrogen inputs:How will change the interaction in this new context?


Acknowledgement

The LBPV team

Financing

IRMS Collaboration

Richard J. RobinsIlla TeaIngrid AntheaumeNadia Guignard

Philippe SimierPhilippe DelavaultJ-B PouvreauThomas Péron (Pictures)Marie Voisin (Map)Mathieu Gauthier Johannes Schmit


Thank you for your attention

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