Effects of arbuscular mycorrhizal fungi and Bradyrhizobium japonicum on drought stress of soybean

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1 S324 Biologi, Brtislv, 61/Suppl. 19: S324 S328, 2006 Effts of rusulr myorrhizl fungi n Bryrhizoium jponium on rought strss of soyn Nssr Alisghrz, Mohmm Rz Nyshouri & Gho Slimi Dprtmnt of Soil Sin, Fulty of Agriultur, Univrsity of Triz, Triz, I.R. of Irn; fx: , -mil: n-lisghr@trizu..ir Astrt: Myorrhizl symiosis n potntilly improv wtr uptk y plnts. In ontroll pot ultur xprimnt, soyn plnts wr inoult with two spis of rusulr myorrhizl fungi, Glomus moss (Gm) or Glomus tunitum (G), or lft non-inoult (NM) s ontrol in stril soil. Four lvls of soil moistur (Fil pity, 0.85 FC, 0.7 FC, 0.6 FC) in th prsn or sn of th Bryrhizoium jponium, wr ppli to th pots. Rltiv wtr ontnt (RWC) of lf t oth plnt growth stgs (flowring n s mturtion) rs with th rynss of soil; RWC ws highr in ll myorrhizl thn non-myorrhizl plnts irrsptiv of soil moistur lvl. At th lowst moistur lvl (0.6 FC) G ws mor ffiint thn Gm in mintining high lf RWC. Lf wtr potntil (LWP) h th sm trn s RWC in flowring stg ut it ws not signifintly influn y rs in soil moistur to 0.7 FC uring s mturtion stg. S n shoot ry wights wr fft ngtivly y rought strss. Myorrhizl plnts, howvr h signifintly highr s n shoot ry wights thn non-myorrhizl plnts t ll moistur lvls xpt for s wight t 0.6 FC. Root myorrhizl oloniztion ws positivly orrlt with RWC, LWP, shoot N n K, n s wight, implying improvmnt of plnt wtr n nutritionl sttus s rsult of oloniztion. Rgrlss of moistur trtmnts, tril inoultion us signifint nhnmnt in N ontnt n th highst N ourr in rhizoil inoult plnts t 0.85 FC n 0.7 FC. Shoot K ws nhn onsirly y oth tril n fungl inoultions, prtiulrly in plnts with ul inoultions whr th highst shoot K lvls wr foun. Th rltivly highr shoot n s ry wights in plnts inoult with oth G. tunitum n B. jponium oul sri to thir highr RWC n LWP, suggsting tht rought voin is min mhnism of this plnt-miro ssoition in llvition of wtr strss in soyn. Ky wors: soyn, rusulr myorrhizl fungi, rought strss, B. jponium Introution Wtr fiit is n importnt ioti ftor limiting plnt growth n yil in mny rs on th rth tht is inrsingly topil us of limt hng n wtr shortgs (Ruiz-Lozno t l., 2001; Jfrzh & Asi, 2006). Svrl o-physiologil stuis hv monstrt tht rusulr myorrhizl (AM) symiosis oftn rsults in ltr rts of wtr movmnt into, through n out of th host plnt, with onsqunt ffts on tissu hyrtion n plnt physiology. It is now pt tht th ontriution of AM symiosis to plnt rought tolrn is th rsult of umultiv physil, nutritionl, physiologil n llulr ffts (Agu, 2001). Th pionr stuis of Alln (1982) n Hri (1985) init possil rol of AM fungl in wtr uptk n trnsfr to th host plnt. Alln (1991) stimt tht th rt of wtr trnsport y xtrril hyph to th root ws 0.28 ng s 1 pr ntry point, lvl suffiint to moify plnt wtr rltions. Anothr mhnism for inrsing rought rsistn in plnts is osmoti justmnt whih llows lls to mintin turgor n th prosss tht pn on it, suh s llulr xpnsion n growth, stomtl opning n photosynthsis, s wll s kping grint of wtr potntil fvorl to wtr ntrn into th plnt (Ruiz-Lozno, 2003). Th soluts tht prtiipt in osmoti justmnt r inorgni ions (minly K + ) or unhrg orgni ompouns prolin or glyin tin s wll s rohyrts lik suros, pinitol or mnnitol (Alisghrz t l., 2005; Ruiz-Lozno, 2003). In ition, othr stuis hv shown tht th AM symiosis n llvit rought-inu noul snsn in lgum plnts. Th most rmrkl osrvtion ws th sustntil rution in oxitiv mg to lipis n protins in nouls of myorrhizl plnts sujt to rought s ompr to th nouls of non-myorrhizl plnts (Ruiz-Lozno t l., 2001). Drought rsistn in plnts n our vi rought voin (mintnn of high intrnl wtr potntil) or rought tolrn (survivl of low intrnl wtr potntil) (Lulow, 1989). In this rspt, rltiv wtr ontnt (RWC) n wtr potntil (LWP) of lf r suitl prm-

2 Effts of myorrhizl fungi on rought strss of soyn S325 Tl 1. Anlysis of vrin (mn squrs) of th ffts of myorrhizl fungi, Bryrhizoium n soil moistur lvls on RWC, LWP, s n shoot ry wights n shoot N n K. Sour of vrin f RWC LWP Dry wight Shoot Fl Sm Fl Sm s shoot N K Blok * * * Btri(B) * 5.241** 0.057** Fungi (F) ** 0.033** 9.661** ** 5.808** ** 1.581** 0.186** BxF ** 0.007* Moistur(M) ** 0.046** ** ** 4.947** ** 0.823** BxM FxM * 0.001** ** 2.295** BxFxM Error *, ** signifint t α lvls of 0.05 n 0.01, rsptivly RWC, rltiv wtr ontnt; LWP, lf wtr potntil; Fl, flowring stg; Sm, s mturtion stg. trs for vlution of plnt wtr sttus whih hv n gin lss ttntion in myorrhizl rltionships. Also, th nutritionl sttus of plnts influns thir wtr ln n stomtl hviour. Lf potssium n nitrogn onntrtions, for xmpl, r intgrlly involv in th physiology of stomtl opning n losing (Mnsfil t l., 1990). This stuy ws unrtkn to trmin th ffts of oth myorrhizl n rhizoil symiosis on lf RWC n LWP, plnt growth, s proution s wll s K n N sttus of soyn plnts in wtr-strss onition. Mtril n mthos In ontroll pot ultur xprimnt, soyn (Glyin mx L. v. Hrkor) plnts wr inoult with two spis of rusulr myorrhizl fungi, Glomus moss (NICOL n GERD) GERDEMANN n TRAPPE (Gm) or Glomus tunitum BECKER n GERDEMANN (G), or lft nonmyorrhizl (NM) s ontrol in stril soil. Th soil us in this stuy ws sny lom in txtur, slinity msur (1.8 S m 1 ), ph 7.2, n low orgni ron (3900 mg kg 1 ) n vill NHCO 3 xtrtl P of 4.4 mg kg 1 n mium vill K of 200 mg kg 1. Four lvls of soil moistur (Fil Cpity, 0.85 FC, 0.7 FC n 0.6 FC) in th prsn or sn of Bryrhizoium jponium KIRCH- NER (JORDAN) wr ppli to th pots. Soil moistur t FC ws 15.7% (w/w). Pots wr wigh vry othr y n wtr ws whn thir soil wtr ontnt ropp to out 10% low th sir lvl (ALIASGHARZAD t l., 2005). Bs on soil hmil nlysis, potssium sulft t rt of 44 mg kg 1 ws vnly to th pots to supply suffiint K lvls. Th xprimnt ws onut in grnhous with vrg ytim n nighttim tmprturs of 28 ± 2 Cn18± 2 C rsptivly, n vrg y lngth of 14 hours from Jun to Otor Th pots wr rrng in ftoril rnomiz lok sign with thr ftors (fungi, tri n soil moistur lvls) n four rplitions. Rltiv wtr ontnt (RWC) n lf wtr potntil (LWP) wr msur t two plnt growth stgs: flowring n s mturtion (BENNET t l., 1987). At hrvst, s n shoot ry wights, n onntrtions of N n K in shoots wr msur (COTTENIE, 1980). Roots wr lr n stin for trmintion of myorrhizl root oloniztion prntg (DALPE, 1993). Rsults n isussion Rltiv wtr ontnt Th min ffts of AM fungi (F) n moistur lvls (M) n th intrtion of FxM wr signifint (p < 0.01) on lf RWC t oth plnt growth stgs (T. 1). Lf RWC t oth plnt growth stgs rs with inrs in wtr strss n RWC ws highr in ll myorrhizl thn non-myorrhizl plnts irrsptiv of soil moistur lvl. At th lowst moistur lvl (0.6 FC) th fungus G ws mor ffiint thn Gm in mintining high lf RWC (Figs 1, 2). Hri (1985) rport tht AM fungl hyph with imtr of 2 5 µm npntrt soil pors inssil to root hirs (10 20 µm imtr) n so sor wtr tht is not vill to non-myorrhizl plnts. Fr t l. (1991) msur rts of wtr trnsport y AM fungl hyph rnging from 375 to 760 nl H 2 Oh 1. Ruiz-Lozno & Azon (1995) in thir xprimnt with lttu plnts sign n AM hyphl omprtmnt in th root zon using 50-µm nylon srn tht llow pntrtion y AM hyph ut not y roots; wtr ws ppli y injtion to this omprtmnt. Thy foun n inrs in plnt frsh wight of nrly 150% in myorrhizl s ompr RWC (%) Fig. 1. Efft of myorrhizl fungi n soil moistur lvls on lf RWC of flowring stg. Arvitions: FC fil pity; RWC rltiv wtr ontnt of lf; NM non-myorrhizl; Gm Glomus moss; G Glomus tunitum. f

3 S326 RWC (%) Fig. 2. Efft of myorrhizl fungi n soil moistur lvls on lf RWC of s mturtion stg (s Fig. 1 for rvitions). LWP (KP) flowring mturtion Fig. 3. Min fft of soil moistur lvls on lf wtr potntil (LWP) t two plnt growth stgs. LWP (KP) flowring mturtion Fig. 4. Min fft of myorrhizl fungi on lf wtr potntil t two plnt growth stgs (s Fig. 1 for rvitions). to th non-myorrhizl plnts. Similrly, lf wtr ontnt inrs in myorrhizl plnts with wtr ppli to th hyphl omprtmnt. Lf wtr potntil Th min ffts of AM fungi n moistur lvls wr signifint (p < 0.01) on LWP t oth plnt growth stgs (T. 1). Lf wtr potntil h th sm trn s RWC in th flowring stg, ut it ws not signifintly influn y rs in soil moistur to 0.7 FC uring th s mturtion stg. In similr moistur lvls n myorrhizl trtmnts, LWP ws highr (lss ngtiv) t flowring thn s mturtion stg (Figs 3, 4). Both myorrhizl plnts h highr LWP t two growth stgs, thn nonmyorrhizl plnts. Howvr, G ws mor ffiint thn Gm in mintining highr LWP (Fig. 4). It sms N. Alisghrz t l. tht rought voin is th min mhnism of AM fungi in th llvition of wtr strss in plnts. Th most pt mhnism for inrsing rought rsistn y AM in plnts is osmoti justmnt whih llows lls to mintin turgor n turgor pnnt prosss, suh s llulr xpnsion n growth, stomtl opning n photosynthsis, s wll s kping grint of wtr potntil fvorl to wtr ntrn into th plnt (Aug, 2001). Sfir t l. (1972) hv rport tht th prsn of myorrhiz rs root rsistn to wtr flow in soyns whih oul l to improv wtr ln n high RWC n turgor in lvs. Myorrhizl n non-myorrhizl plnts lso oftn show iffrnt ritil points or thrshols of stomtl hviour unr wtr strss onition. For xmpl, lf wtr potntil ws out 0.2 MP lowr in myorrhizl wht plnts thn in similr-siz nonmyorrhizl plnts whn th stomt gn to los (Alln & Booslis, 1983). Similrly, lf wtr potntil t stomtl losur ws 0.7 MP lowr in AMF ros plnts thn in non-myorrhizl plnts of th sm siz (Aug t l., 1986). S n shoot ry wights Th min ffts of AM fungi n moistur lvls n th intrtion of FxM wr signifint (p < 0.01) on s n shoot ry wights, ut th min fft of tri ws only signifint (p < 0.05) on shoot ry wight (T. 1). S n shoot ry wights wr ngtivly fft y wtr strss. Myorrhizl plnts, howvr h signifintly highr s n shoot ry wights thn non-myorrhizl plnts t ll moistur lvls xpt for s wight t 0.6 FC (T. 2). Shoot N n K Th min ffts of tri (B) n fungi (F) n th intrtion of BxF wr signifint (p < 0.01) on shoot N n K onntrtions, ut th min fft of moistur lvls ws only signifint (p < 0.05) on shoot N (T. 1). Rgrlss of th moistur trtmnts, tril inoultion us signifint nhnmnt in shoot N. B. jponium my improv soyn growth in wtr-strss onition y supplying nitrogn. Rin (1990) point out tht lf N onntrtion n fft stomtl hviour. Although myorrhizl fungi h no signifint fft on shoot N, ut in nontril plnts it inrs slightly in th prsn of ithr fungi (T. 3). Root noul numr n frsh wight wr not fft y moistur lvls until 0.7 FC, ut thy wr signifintly iminish t 0.6 FC. Rution in oxitiv mg to lipis n protins in nouls of myorrhizl plnts sujt to rought, s mntion ov, n llvit rought inu noul snsn in lgum plnts. Morovr, AM symiosis n inrs th glutthion ruts (GR) tivity onsirly oth in roots n nouls of soyn plnts sujt to rought strss (Porl t

4 Effts of myorrhizl fungi on rought strss of soyn S327 Tl 2. Intrtion of moistur lvls n myorrhizl fungi on s n shoot ry wights. Moistur Lvls Fungi NM* Gm G Nm Gm G S (g plnt 1 ) Shoot (g plnt 1 ) f 1.8f 2.6 Mns in h row follow y sm lttr r not signifintly iffrnt (p < 0.05) (* s Fig. 1 for rvitions). Tl 3. Intrtion of myorrhizl fungi n tril inoultions on shoot K n N onntrtions. Btri Without Bryrhizoium With Bryrhizoium Fungi NM* Gm G K(mgg 1 ) N (%) Mns in h row follow y sm lttr r not signifintly iffrnt (p < 0.05) * s Fig. 1 for rvitions l., 2003). Shoot K ws nhn onsirly y oth tril n fungl inoultions n th highst ws hiv in plnts with ul inoultions (T. 3). Contriution of K + in osmoti justmnt n stomtl onutn of plnts hs lry n rport (Ruiz- Lozno, 2003). Root myorrhizl oloniztion Root myorrhizl oloniztion ws positivly orrlt with RWC, LWP, shoot N n K, n s wight, implying improvmnt of plnt wtr n nutritionl sttus s rsult of myorrhizl oloniztion. Givn th highr RWC n LWP in myorrhizl thn non-myorrhizl plnts in this stuy, it n onlu tht myorrhizl fungi my ontriut to inrs rought voin ility of plnts, thus ling to llvition of wtr strss in soyn. Myorrhizl n tril inoult plnts h rltivly highr K n N in shoots. Potssium n nitrogn r two ssntil nutrints tht ply ky rol in osmoti justmnt n stomtl hviour. Th rltivly highr shoot n s ry wights in plnts inoult with oth G. tunitum n B. jponium oul sri to thir highr RWC n LWP, suggsting tht plnt wtr sttus is fftivly improv y this plnt-miro ssoition. Rfrns ALIASGHARZAD, N., BARIN, M. & SAMADI, A Effts of NCl-inu n mixtur slinitis on lf prolin n growth of tomto in symiosis with rusulr myorrhizl fungi, pp In: Pro. of th Int. Conf. on Environ. Mngmnt, Otor 2005, Hyr, Ini. ALLEN, M.F Influn of vsiulr-rusulr myorrhiz on wtr movmnt through Butlou grilis LAG x STEUD. Nw Phytol. 91: ALLEN, M.F.&BOOSALIS. M.G Effts of two spis of VA myorrhizl fungi on rought tolrn of wintr wht. Nw Phytol. 93: ALLEN, M.F Th ology of myorrhiz. Cmrig Univrsity Prss, Cmrig. AUGE, R.M., SCHECKEL, K.A.& WAMPLE, R.L Grtr lf onutn of wll wtr VA myorrhizl ros plnts is not rlt to phosphorus nutrition. Nw Phytol. 103: AUGE, R.M Wtr rltions, rought n vsiulrrusulr myorrhizl symiosis. Myorrhiz 11: BENNET, J.M., SINCLAIR, T.R., MUCHOW, R.C.&CUSTELL, S.R Dpnn of stomtl onutn on lf wtr potntil, turgor potntil n rltiv wtr ontnt in fil grown soyn n miz. Crop Si. 27: COTTENIE, A Mthos of plnt nlysis, pp In: Soil n Plnt Tsting. FAO Soils Bulltin 38/2. DALPE, Y Vsiulr-rusulr myorrhiz pp In: CARTER, M.R. (.), Soil smpling n mthos of nlysis, Lwis Pulishrs. FABER, B.A., ZASOSKI, R.J.& MUNNS, D.N A mtho for msuring hyphl nutrint n wtr uptk in myorrhizl plnts. Cn. J. Bot. 69: HARDIE, K Th fft of rmovl of xtrril hyph on wtr uptk y VAM plnts. Nw Phytol. 101: JAFARZADEH, A.A.& ABBASI, G Qulittiv ln suitility vlution for th growth of onion, potto, miz n lflf on soils of th Khlt Pushn Rsrh Sttion. Biologi, Brtislv 61(Supl. 19): S349 S352. LUDLOW, M.M Strtgis in rspons to wtr strss, pp In: KREEB, H.K., RICHTER, H.& HINCKLEY, T.M. (s), Struturl n Funtionl Rsponss to Environmntl Strsss: Wtr Shortg. SPB Ami, Th Hgu. MANSFIELD, T.A., HETHERINGTON, A.M. & ATKINSON, C.J Som urrnt spts of stomtl physiology. Annu. Rv. Plnt Physiol. Plnt Mol. Biol. 41: PORCEL, R., BAREA, J.M.& RUIZ-LOZANO, J.M Antioxint tivitis in myorrhizl soyn plnts unr rought strss n thir possil rltionship to th pross of noul snsn. Nw Phytol. 157: RADIN, J.W Rsponss of trnspirtion n hyruli onutn to root tmprtur in nitrogn- n phosphorusfiint otton slings. Plnt Physiol. 92: RUIZ-LOZANO, J.M.& AZCON, R Hyphl ontriution to wtr uptk in myorrhizl plnts s fft y th fungl spis n wtr sttus. Physiol. of Plnt 95: RUIZ-LOZANO, J.M., COLLADOS, C.,BAREA, J.M.&AZCON, R Arusulr myorrhizl symiosis n llvit rought- inu noul snsn in soyn plnt. Nw Phytol. 151:

5 S328 N. Alisghrz t l. RUIZ-LOZANO, J.M Arusulr myorrhizl symiosis n llvition of osmoti strss. Nw prsptivs for molulr stuis. Myorrhiz 13: SAFIR, G.R., BOYER, J.S.& GERDEMANN, J.W Nutrint sttus n myorrhizl nhnmnt of wtr trnsport in soyn. Plnt Physiol. 49: