Arbuscular Mycorrhizal Colonisation Modifies the Water Relations of Young Transplanted Grapevines (Vitis)

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1 Arusculr Mycorrhizl Colonistion Modifies the Wter Reltions of Young rnsplnted Grpevines (Vitis) M. vn Rooyen 1, A. Vlentine 2 * nd E. Archer 3 ** (1) Deprtment of Botny, Stellenosch University, Privte Bg X1, 762 Mtielnd (Stellenosch), South Afric (2) Deprtment of Environmentl Sciences, Fculty of Applied Sciences, Cpe Peninsul University of echnology, PO Box 652, 8 Cpe own, South Afric (3) Deprtment of Viticulture & Oenology, Stellenosch University, Privte Bg X1, 762 Mtielnd (Stellenosch), South Afric Sumitted for puliction: June 22 Accepted for puliction: August 24 Key words: Wter reltions, photosynthesis, mycorrhizs, trnsplnttion he effect of rusculr mycorrhizl (AM) colonistion on the llevition of trnsplnttion shock in young grpevines ws investigted. One-yer-old grpevines (Suvignon lnc on Richter 99), colonised with Glomus etunictum (Becker nd Gerdemnn), were cultivted in n tmosphere-controlled tunnel. Wter reltions, lef photosynthetic prmeters nd growth chrcters were evluted. AM colonistion enhnced the photosynthetic performnce of host plnts, ut hd no influence on iomss nd minerl nutrition of the trnsplnted hosts. he incresed photosynthetic rtes of the AM plnts were relted to improved wter reltions. Stomtl conductnce, trnspirtion rte nd middy xylem wter potentil were higher in the AM hosts during the trnsplnted period. hese results indicte tht AM inocultion cn influence the wter reltions of trnsplnted grpevine rootstocks, therey improving photosynthetic performnce nd potentil survivl during the initil growth stges of the host plnts. he role of rusculr mycorrhiz (AM) in enhncing plnt growth nd yield of crops hs een previously reported (Boln, 1991). In this regrd one of the gretest potentil enefits of AM fungi for host plnts is the increse in iomss nd growth of the host plnts. his increse in growth nd iomss my e cused y the host plnt's incresed ility to cquire essentil nutrients nd wter (Ruiz-Lozno & Azcon, 1995). he eneficil effect of mycorrhize is of specil importnce to plnts such s grpevines tht hve corse nd poorly rnched root system. Grpevines pper to e relint on AM fungl colonistion for norml growth nd development (Menge et l., 1983; Krginnidis et l., 1995; Biricolti et l., 1997; Lindermn & Dvis, 21). Furthermore, it ws found tht corse-rooted species, such s vines (Motosugi et l., 22) re more relint on AM colonistion thn fine-rooted species (Boln, 1991; Eissenstt, 1992). he fungl species nd the rootstock cultivr will determine mny of the enefits ttriuted to the symiosis (Menge et l., 1983; Schuert et l., 1988; Krginnidis et l., 1997). Schuert et l. (1988) inoculted different rootstock cultivrs with different AM fungi nd found tht certin fungl species comined with specific rootstocks incresed plnt growth to greter extent thn other comintions did. he percentge colonistion, degree of growth response nd nutritionl enefits of AM colonistion of vine roots will vry ccording to the AM fungl species nd the rootstock cultivr involved (Lindermn & Dvis, 21; Schreiner, 23). Vineyrds infected with soil pthogens such s phylloxer often require fumigtion tretments. However, the fumignt clers the soil of oth desired nd undesired soil microes, including AM fungi (Menge et l., 1983; Lindermn & Dvis, 21). herefore the inocultion of vines efore plnting in fumigted soils is needed to ensure AM fungl colonistion of the vine roots. Menge et l. (1983) reported tht non vines plnted in fumigted soils hd stunted growth compred to the inoculted vines. his trnsplnttion shock of the vines my e relted to root-system dmge (Wschkies et l., 1993), which my impir wter nd nutrient uptke. he phenomenon of trnsplnttion shock hs een found to e reduced y inoculting the vines with AM fungi (Lindermn & Dvis, 21). It is currently not known how AM colonistion could medite n llevition of the trnsplnttion shock in young grpevines, ut the evidence of root-system dmge (Wschkies et l., 1993) suggests tht AM fungi my improve wter reltions nd nutrient ccess of host plnts. he ojective of this study ws therefore to ssess the contriution of single-strin AM inoculum on the host-wter reltions nd the consequent impct of this on minerl nutrition, photosynthesis nd growth of trnsplnted grpevine rootstocks. he rootstocks were inoculted during trnsplnttion nd the host performnce ws ssessed fter 9 dys of growth. MAERIALS AND MEHODS Growth conditions One-yer-old grfted grpevine cuttings (Vitis vinifer L. cv. Suvignon lnc, grfted onto Richter 99 rootstocks) were plnt- *Corresponding uthor: E-mil ddress: vlentine@ctech.c.z **Present ddress: Lusn Premium Wines (Pty) Ltd. PO Box Stellenosch, South Afric. S. Afr. J. Enol. Vitic., Vol. 25, No. 2, 24 37

2 38 Wter Reltions in Mycorrhizl Grpevines ed in 2-litre pots, contining irrdited (2 kgy) filter snd with grin size of.51 mm nd ph of 7. Registered, commercil Vi tis vinifer L. cv. Suvignon lnc grfted onto Richter 99 rootstocks were selected to hve similr shoot thickness nd root development. he plnts were grown for 9 dys in north-fcing tunnel t the University of Stellenosch, Western Cpe, South Afric. he mximum dily photosyntheticlly ctive irrdince ws etween 7 nd 8 Jlmol m-2 s- 1 nd the verge dy/night tempertures were 23!19 C. he trnsplnted grpevines were wtered with stndrd Long-Ashton nutrient solution modified to contin NOdNH4+ s N source nd 1 JlM P. he solution ws dded every seven dys t field cpcity (2 1) of the snd. Inocultion he inoculum consisted of single-strin pure culture (spores nd frgments of roots nd hyphe in n inert crrier, collected from pot culture) of n AM species, Glomus etunictum (supplied y Dr C. Strker from University of the Witwtersrnd). he spore density of the inoculum ws 12 spores/g. he AM grpevines were inoculted nd the control plnts received filtered inoculum solution, which ws prepred y filtering the inoculum through 37 Jlm mesh to remove the mycorrhizl fungl mteril. Inocultion ws conducted y spreding the inoculum round the roots in the plnting hole. he pot ws then filled up with the snd covering the roots nd the inoculum. his ensured tht the propgted roots were immeditely in contct with the AM fungl propgules. Plnt hrvest At 9 dys of pot culture the physiologicl mesurements were tken nd the plnts were hrvested. he lef res of the plnts were mesured with lef re meter (Licor, model LI-3, Lmd Instruments Corportion, USA) nd the wter potentil ws determined with pressure chmer (PNS intruments Co. Oregon USA). he roots were crefully lotted dry, root pieces of the root were rndomly cut off, weighed nd stored in vil with 5% ethnol (v/v) solution for estimtion of mycorrhizl colonistion. he components were dried t 8 C for more thn 72 h nd weighed to determine the dry weight. he iomss prmeters were clculted s follows. Lef-re rtio is the rtio of totl lef re reltive to totl plnt mss. Specific lef mss descries the density of leves, expressed s lef mss per lef re (kg/m2). Reltive growth rte is the specific growth (mg) for n existing plnt mss (g) over time (mg/g/dy). Growth rte is the verge growth for given period (g/dy). he iomss Nnd P use efficiencies express the rtio of totl plnt dry mtter ccumulted per mount of totl plnt N or P (g dw/mmol N or P). Mycorrhizl colonistion During plnt hrvest, the thin lterl roots were removed nd stored in 5% ethnol. Root segments were clered in 2.5% KOH in n Autoclve for 6 minutes (hot clering). Afterwrds, the KOH ws rinsed from the segments nd cidified with 1% HCL for 24 ht room temperture. he roots were stined with.5% Anline lue in 7% cidified glycerol for 48 h t room temperture. Roots were cut into 1 em pieces nd rndomly selected to e pcked on slides. hey were susequently exmined t x 4 mgnifiction under light microscope. Infection ws determined ccording to the methods descried y Brundrett et l. (1994). Photosynthesis he youngest fully expnded lef for ech plnt ws used for the photosynthetic determintions. he photosynthetic rte (Pn), stomtl conductnce (Gs) nd trnspirtion rte (E) were determined t middy, using portle infrred gs nlyser (LiCor). Photosynthetic nitrogen-use efficiency (PNUE) nd photosynthetic phosphorus-use efficiency (PPUE) were otined y dividing Pn y either the lef N or P concentrtion, respectively. Photosynthetic wter-use efficiency (PWUE) ws clculted from mesurements of Pn nd trnspirtion rte. Intercellulr COz response curves were determined using the fcility on the infrred gs nlyser, y mnully djusting the C2 concentrtion in the lef chmer. he C2 response curves were used to clculte electron trnsport cpcity nd RUBISCO ctivity, using the equtions of Wtne et l. (1994). Chemicl nlyses Chlorophyll nlyses were performed on lef discs tken from the sme leves which were used for the gs exchnge mesurements. Chlorophyll ws extrcted t 4 C in cetone. he resulting extrct ws centrifuged t 3 g for 3 minutes, nd the chlorophyll concentrtion ws determined ccording to the method of Amon (1949) y mesuring the sornce t 646, 663 nd 71 nm in spectrophotometer. he oven-dried (72 h, 8 C) plnt mteril of ech tretment ws milled in Wiley mill (A.H. homs, Phildelphi, P, USA) using 6 mesh screen, for lef, stem nd root mteril. he plnt mteril ws nlysed y BEM LABS (Somerset West, RSA) for N nd P. Xylem wter potentil Xylem wter potentils (XWP) were tken t middy, using pressure chmer (PNS Instruments Co. Oregon, USA). A terminl rnch ering the first fully expnded lef ws plced in the pressure om, with the lef inside the chmer nd cut surfce of the stem protruding from the chmer. he pressure ws grdully incresed, until the xylem sp evenly covered the cut surfce. At this point the pressure ws turned off nd recorded s the wter potentil. Sttisticl nlyses Plnts were spced in rndom lock design. he percentge dt were rcsine trnsformed (Zr, 1984). he influence of the fctor, mycorrhizl inocultion, ws tested with one-wy nlysis of vrince (1-wy ANOVA) nd the differences etween tretments were seprted using post hoc Student Newmn Kuels (SNK), multiple comprison test (SuperANOVA version for Mcintosh). Different letters indicte significnt differences etween tretments (P$;.5), n= 5. RESULS Roots inoculted with live AM hd 61% colonistion, whilst the control plnts remined non-mycorrhizl for the durtion of the tril (le 1). he presence of AM colonistion did not influence the iomss of the host plnts nd there were no differences in growth prmeters etween AM nd non plnts (le 1). N nd P nutrition of the host plnts lso remined unffected y AM colonistion (le 2). In spite of the sence of differences etween AM nd non iomss nd nutrition, the net photosynthetic (Pn) gs exchnge nd lef wter reltions were significntly influenced y AM S. Afr. J, Enol. Vitic., Vol. 25, No. 2, 24

3 Wter Reltions in Mycorrhizl Grpevines 39 ABLE 1 Biomss-prmeters of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N3/NH4 nd 1 1-1M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween nd tretments in ech row (P:::;.5). Prmeters Lef dt lef dry mss (g) 1.33 ± ±.13 lef fresh mss (g) 4.54 ± ±.62 lef re (m2) ± ±31.84 lef numer ± ±2.91 lef re rtio.15 ±.1.13 ±.1 specific lef mss (kgfm2) 4.58 ± ±.3 Biomss root dry mss (g) 18.7 ± ±1.93 shoot dry mss (g) ± ±4.61 totl plnt dry mss (g) ± ±6.84 root: shoot.77 ±.4.9 ±.13 plnt reltive growth rte (mg/g/dy).981 ± ±3.391 plnt growth rte (g/dy).497 ± ±.76 Arusculr mycorrhizl colonistion ABLE3 Phototsynthetic prmeters of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N 3 nd 1 1-1M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween nd tretments in ech row (P:::;.5). Prmeters Photon yield.231 ±.5.26 ±.19 Ruisco ctivity (!J.mol COz m 2.s- 1) ± ±3.825 Electron trnsport ctivity (!J.mol COz nr 2 s- 1 ) ± ± Chlorophyll (!J.moi.m-2) ± ± Chlorophyll (!J.moi.m-2) ± ± Chlorophyll : 3.56 ± ±.321 otl Chlorophyll (!J.moi.m-2) ± ± Photosynthetic N-use effciency (!J.mol COz mmo]- 1 N m 2.s-l) O.D18 ±.3.12 ±.1 Photosynthetic P-use effciency (!J.mol C2 mmo!" 1 P m 2.s- 1 ).3 ±.1.2 ±. root colonistion with AM (%) ± ±7.72 ABLE2 Nnd P concentrtions of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N3/NH4 nd 1 1-1M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween nd tretments in ech row (P:::;.5) L j_ Prmeters N concentrtion (mmol N/g dw) 2.5 root N stemn lefn iomss N-use efficiency (g dw/ mmol N) P concentrtion (mmol P/g dw) root P stemp lefp iomss P-use efficiency (g dw/nunol P) ±1.37 ±.9 ±1.14 ±.1 ±.24 ±.16 ±.33 ± ±.13 ±.62 ±.51 ±.5 ±.43 ±.4 ±.27 ±.4 FIGURE I Photosynthetic rtes (Pn) of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2!J.M N3/NH4 nd 1!J.M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween the two tretments (P:;:;.5). S. Afr. J. Enol. Vitic., Vol. 25, No. 2, 24

4 4 Wter Reltions in Mycorrhizl Grpevines... - /! = 5 = ll.l L = Q, -.5 '"" L = -1.5 j_ FIGURE2 Stomtl conductnce (GS) of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which then concentrtion ws modified to 2 mm N3/NH4 nd 1 J.!M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween the two tretments (P$.5). FIGURE 3 Xylem sp pressure potentil (XWP) of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N3/NH4 nd 1 J.!M P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween the two tretments (P$.5) /!2 1. N = -.L = = N 7.5 = 1 = j_ u 5 - ::::l. = 2.5 p FIGURE4 rnspirtion rte (E) of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws Jive Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N3/Nf4 nd 1 J.!M P. he vlues represent verges with stndrd error(±). he different letters indicte significnt differences etween the two tretments (P$.5). FIGURE 5 Photosynthetic wter use efficiency (PWUE) of 9-dy-old nd grpevines, grown in pots contining sterilised filter snd. he inoculum ws live Glomus etunictum, whilst the inoculum ws n irrdited Glomus etunictum smple, contining filtrte of the non-mycorrhizl microes present in the live inoculum. he plnts received stndrd Long-Ashton nutrient solution in which the N concentrtion ws modified to 2 mm N3/NH4 nd 1 JlM P. he vlues represent verges with stndrd error (±). he different letters indicte significnt differences etween the two tretments (P$.5). S. Afr. J. Enol. Vitic., Vol. 25, No. 2, 24

5 Wter Reltions in Mycorrhizl Grpevines 41 colonistion. he Pn rte ws higher in the AM leves compred to the non leves (Fig. 1), ut this ws not relted to other lef photosynthetic prmeters (le 3). In this regrd, RUBIS CO ctivity, electron trnsport cpcity, chlorophyll levels, photosynthetic nutrient-use efficiencies nd photon yield were unffected y AM colonistion (le 3). Insted, the incresed Pn corresponded with enhnced stomtl conductnce (Gs) (Fig. 2) nd trnspirtion rtes (E) (Fig. 4) in the AM leves. Middy xylem wter potentils (XWP) were lower (less negtive) in the AM plnts, implying less wter stress thn in the non controls (Fig. 3). However, the higher photosynthetic wter-use efficiency (PWUE) of the AM plnts indictes tht AM host plnts lost more wter thn non plnts during photosynthetic C2 fixtion (Fig. 5). DISCUSSION he sence of increses in iomss nd minerl nutrition of AM colonised grpevines contrdicts erlier findings of mycorrhizl enefits to host grpevines (Possinghm & Oink, 1971; Menge et!., 1983). However, the improved rte of photosynthesis (Pn) in AM plnts is congruent with other studies of herceous hosts (Allen et l., 1981; Levy & Kirkun, 198; Vlentine et!., 21; 22), s well s grpevine hosts (Nikolou et!., 23 ). In prticulr the present study concurs with Nikolou et l., (23), who lso demonstrted tht AM-colonised vines hd higher C2 ssimiltion rtes thn uncolonised vines, ut with no increse in the iomss of the host plnts. Since the increse of Pn in the AM plnts occurred in the sence of improved nutrient sttus or the derived photosynthetic prmeters, it is therefore proposed to e relted to n AM sink effect or n AM-induced chnge in wter reltions. he ssocition of the increse in Pn nd the percentge of AM colonistion suggests reltionship etween AM colonistion nd crohydrte vilility, s proposed y Vlentine et l. (21; 22).1t is well known tht the demnd for photo-ssimiltes cn stimulte the rte ofpn (Neles & Incoll, 1968; Herold, 198; Foyer, 1987) nd since lrge proportion of photosynthetic product is llocted to the root of AM plnts (Mrschner, 1995; Jcosen & Rosendhl, 199), this is one potentil mechnism for the oserved increses in Pn of AM plnts. he improved wter reltions, s nother potentil mechnism of the AM stimultion of host Pn, hve een cuslly relted to Pn vi increses in the stomtl conductnce (Gs) of the AM plnts (Allen et l., 1981; Brown & Bethelenflvy, 1987; Fitter, 1988; Vlentine et l., 21; 22). In the present study the improved Gs, trnspirtion rte nd xylem wter potentil in AM grpevines, provide sufficient evidence tht the wter sttus ws incresed y AM colonistion. Previous studies (Giovnetti & Mosse, 198; Grhm & Syverston, 1984) found tht the ltered wter sttus of the AM plnts ws closely ssocited with n improved host nutrition, prticulrly P. hese findings do not concur with the current study, where host nutrition ws not ffected y AM sttus. However, the present work does concur with other findings (Red, 1992; Sylvi & Willims, 1992; Koide, 1993) where it ws proposed tht mycorrhizl infection cn fcilitte significnt increse of wter flux independent of chnges in the nutrient sttus of the host. Wter uptke y root tissue my therefore e result of the presence of AM fungi on these roots, s ws found y Ruiz-Lozno & Azcon (1995). Motosugi et l. (22) lso reported tht AM-colonised roots were more efficient in the uptke of wter compred to uncolonised roots. Nikolou et l. (23) determined tht AM vines hve n improved wter sttus nd drought-sensitive rootstocks showed greter growth when colonised y n AM fungus under non-irrigted conditions. AM fungi cn therefore id in the uptke of wter nd contriute to n improved wter sttus in vines, enling the vines to grow under low irrigtion or survive wter-stressed conditions. Interestingly, the improved wter sttus y the AM fungi my lso hve cused the AM plnts to llow greter wter loss during photosynthetic C2 ssimiltion. his less efficient PWUE suggests tht the host plnts re le to spend more wter under conditions of sufficient wter supply y AM fungl symionts. CONCLUSIONS It is concluded tht inocultion of trnsplnted grpevines with AM fungi my improve the plnt wter sttus nd therey increse the potentil llevition of trnsplnttion shock. he AM mechnism of ction on wter reltions ppers to e independent from n improved nutrient sttus. Although AM my contriute to helthier plnt in pot culture, further studies re required to ssess whether the sme enefits re possile under field conditions. he potentil of such future work is supported y the suggestion of Allen & Allen (1986) tht AM fungi re importnt in sustinle griculture ecuse they improve plntwter reltions nd drought resistnce of host plnts. LIERAURE CIED Allen, E.B. & Allen, M.F., Wter reltions of xeric grsses in the field: interctions of mycorrhizs nd competition. New Phytologist 14, Arnon, D.l., Copper enzymes in isolted chloroplst: polyphenoloxidses in Bet vulgris. Plnt Physiol. 24, Allen, M.F., Smith, W.K., Moore,.S. & Christensen, M., Comprtive wter reltions nd photosynthesis of mycorrhizl nd non-mycorrhizl Boutelou grcilis. New Phytologist 88, Biricolti, S., Ferrini, F., Rinldelli, E., mntini, I. & Vignozzi, N., AM fungi nd soil lime content influence rootstock growth nd nutrient content. Am. J. Enol. Vitic. 48, Boln, N.S., A criticl review on the role of mycorrhizl fungi in the uptke of phosphorous y plnts. Plnt Soil 134, Boln, N.S., Roson, A.D. & Brrow, N.J., Effects of vesiculr-rusculr mycorrhiz on the vilility of iron phosphtes to plnts. Plnt Soil99, Brown, M.S. & Bethlenflvy, G.J., Glycine-Glomus-Rhizoium symiosis. VI. Photosynthesis in nodulted, mycorrhizl, or N- nd P-fertilized soyen plnts. Plnt Physiol. 85, Brundrett, M., Melville, L. & Peterson, L., Prcticl Methods in Mycorrhiz Reserch. Micologue Pulictions. Eissenstt, D.M., Cost nd enefits of constructing roots of smll dimeter. J.Plnt Nut. 15, Fitter, A.H., Wter reltions of red clover rifolium prtense L. s ffected y VA mycorrhizl infection nd phosphorus supply efore nd during drought. J. Exp. Bot. 39, Foyer, C.H., he sis for source-sink interction in leves. Plnt Physiol. & Bioch. 25, Giovnni, M. & Mosse, B., 198. An evlution of techniques for mesming vesiculr-rusculr infection in roots. New Phytologist 84, Grhm, J.H. & Syverston, J.P., Influence of vesuculr-rusculr mycorrhiz on the hydrulic conductivity of roots of two citrus root stocks. New Phytologist 97, Herold, A., 198. Regultion of photosynthesis y sink ctivity- the missing link. New Phytologist 86, S. Afr. J. Enol. Vitic., Vol. 25, No. 2, 24

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