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Effect of P availability on the diversity and functioning of mycorrhiza and mycorrhizosphere bacteria in maritime pine stands of the Landes forest ecosystem

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Academic year: 2021

Partager "Effect of P availability on the diversity and functioning of mycorrhiza and mycorrhizosphere bacteria in maritime pine stands of the Landes forest ecosystem"

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54

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Session 2 . Symbioses and plant growth promotion

Rooüng induction

of

olive plants cuttings by plant growtfl promoting rtlizobacteria

Mon!ero

ca!asanz

Marla[)el

Carmen,

5al1arnarialiIaza

cannen.

AIlaredaContreras Marta,Daza Ortega ...CMlad10 Martlnez-VndeRey

Mn

IFAPA,

ceotro

lasTorres-Tomejl • .kJntaDehdatuReanosNatL.raIes YProdua::iOO~eYRA.

CazaIa&vila

KM 12.2 41200 At;alàDelRio

SeviIa

$pail

Chemicalagentsuse<!

to

preYeflldiseases

symptoms

01

to

Iertiizeplants can causedetrirrertalelfects on humanhealthandpersîstin

natu-rai ecosystems

50,inlhelaS!decade COflVefllîooaI chemicalsproducts

are

beingrepIaœdbybioIogi:al

agents.

suctl

as

fTicroorgarisms

(baderiaandmycorrtiz.ae).Adualy,in organic agriaJttureilÎS

forbidden to

use cherricallXlI'l1lOOnds.

Free living soil

bacleria

tha!

proYidesornebenef~teplants are usuaRy referred

to

as plantgrowltrprornoti'gmizobacteria (pGPR).They may

racililale piani growth and developmentindirecltylhroogh lheIr abilityleprevent ordecrease thedamage

to

plants or directly lhrooghiroo

sequestralion, phosphate soIubilizalion ortheprodllClion of plant growtll hormones such asindole-3-aœlic acid (!.Ml, the mas! common auxin which stimulalemolelongation.

AZO$pirillum brasi/ense ha!beenwidely used as a PGPR

owing

ils

capacily

to

produce and release abroadspeçtrum of plant growth regu-lalors. ArronQ several

A.

brasUense slrains,thestrain Cd wasthe0I'Iethatproduœdthehighest levelsofIAA.

Nowadays,theolive propagation adopled by nutsel)' growers,ismoslly lhrooghsemi-woodyClive plants cuttings. They aretreatedduring

several seconds'Nithan lAA solution (24mgIL).The use

of

lMinorganic agricultureis

forbidden

50

ta fine!

anecoIogicalternative 10\tle

use

oflMis needed. ~.

ln Ihiswork

we

na...e studied

rooling

indUClÙlbythelISeofSOO'lebacIeria previ:luslydesaibedas highly eftectiveas auùl'sproduœrs.and

othersisoIaled

from

the rtlizosphere

of

orgaiW::oIiYes

trees.

and

seleded

by

ils

in vitrocapacily"

soIubiize

phosphate.and

ta

produœ

sicle-rophoresandlM..

Effec:t

of

P availability on the diyel'$ity and functioning of

myeorrhïz.a and mycorrhilosphere bacteria in mari·

time pine stands

of

tfM

Landes fores( ecosystem

Dornerwe

Odj!e'.PIassardCIaude', Prin'tYes',Gcrbefteau..llcqun'.B6ltefMart',~Utent",TrictleIPierre',SaurE~.1insi1ger Phiippe',.!damBenolt',NIMt.t1arrmacIArif,M'BaIaJosejlh',OupomcisRom',castelscardine',GaIlana~

'INRAlSTl.l,

campus

Ge

BaIlaf9Jet

TA82IJ 34398MalIpeIercedex5France

1UMRl222BilgéodIimîeduSeleldelaRhizosphère,INRA.sup,t,gro.M,Ml:npeIIier

1Labora:on desS)'TOoses TropicaleselMéci:erranéemes,INRA-IRD-ClRAD-UMJl-SupAgro-M,MonIpeIief

• M)'ooIogieelS6cuité des NimenlS. INAA,.Bordeaux

• Translerlsd-pIanIeelCyc:IesdesEJ6mentsrrin6rauxdanslesEalsyslèmesQ.tIivés.ENrTAB, Bardeaull • Transfertsd-pIanteelCyclesdesEJements minéœuxdanslesEcosysll!mesCtIMs,INRA, BordellUll

'Ec:dogîelonctionn&Ie et physique de l'enviromement, INRA, Bon:leauK

Themaritimepine(Anus pinastet'j, distributedfromI.4otoccanAtianlic coast

ta

South

of

Europe,isthe most p1anted foœstspeciesin France

wiIh1 million hectares

Iocated

inthelandesregion. Mostof these monospecific plantations grow on sandy acidic soiIslhat are deficientin

minerai e!ements, pho$phonJsinparticular. Sincemyrorrhizaassociated

to

pine

roots

play ani~ntrola in P avaUability,thedifferent

far·

Iilizalion regimes applied

ta

pine plantations lhrooghoutthelandes Iofes\ cook! have a direct affect on thediversily and functioningofmycor· rtlizaand lheir associated bactaria.

We analyse<!thedivefsity

of

pine ectomyoorrhiza ancllha\

oflheir

associatedmyconIlizospherebactelia (MB)inthirty representativaforest

sitesral"lQinllfrom 6

ta

93years-old. alol"lQthreesuccessive surveys(autumn 2005

to

autumn2006).AtIefintensive mycootliza samplil"lQs tramsoil

cores

c:ombined

ta

a

systemallc survey 01 sporophores. rnJtochoodrial DNA of rnycorrtllzaandsporophoreswas

sequenœd

(ML5IMl6 primers). MSweillisoIateclon

trypcase

mediumfTom!hesurface of mycoohiza and lheir abilily 10soIubilizePwas assessed atler incubation on TCP agar medium.AmongtheisoIated MB, lIuoresœntpseudoIronads,koown10incaJdemyœnhizationhelperbaderia,

were

also deteded

usng

!heKing's B medium.

The

tirst results

show

a gmt

divel'sityofmycorrhiz.aIspecies(i30)wiIh

a

~of

Russulaceae

speàes.

Clear

ditferenœs

are

obsefwd., the proportionofvariouslungadspecîesacccrdi1g10!hese andbetween~lungalmi::roftora(rnyaJrThiza)and

abc-vegroundone (sporophaes). Theproportionof IllBable10soIubizeinorganicphosphale issignificanltyhigher., non-P.fMIiledplotsthan inthoseregUartyIertiized wiIhP, 70%

vs

45%respediYefy.Amongal theMS isoIiIted.the proportionoflk.IorescentpseudoIronadsvaried

dramatica1ly

acc:ordDg

telthe

season. i.e.

fromabout 5%Ï'lauI1.rm10 45%.,spring.

165 genesequencingof MBwiIbeperfOlTlled toinvestigatespeci6caffinities andlunctionaIrelalionships betweenbacteriaIandlungaIpart.

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