INOCULATION OF MARINE PLANTS WITH MARINE PLANT GROWTH- PROMOTING BACTERIA AND HALOTOLERANT AZOSPIRILLUM

Transcription

1 INOCULATION OF MARINE PLANTS WITH MARINE PLANT GROWTH- PROMOTING BACTERIA AND HALOTOLERANT AZOSPIRILLUM - A NOVEL APPROACH OF EMPLOYING PGPBs FOR ENVIRONMENTAL USE AND SEAWATER AGRICULTURE. Bshn, Y.,(), Moreno, M.(), Puente, M. E.,(), Holguin, G.,(,3), Vzquez, P.,(), Troyo, E.,(), nd Glick, B. R.,(3).. Environmentl Microiology;. Progrm of Agroecology, The Center for Biologicl Reserch of the Northwest (CIB), L Pz, B.C.S., 3, Mexico; 3. Dept. Biology, University of Wterloo, Wterloo, ON NL 3G, Cnd. Mngroves re tropicl nd sutropicl trees tht re the mjor component of costl mrine-lgoon ecosystems nd serve s feeding, spwning, nd reproductive res for numerous economiclly nd ecologiclly importnt mrine species (9). Tropicl mngroves generlly selfrevegette fter clercutting. However, in semirid tropics, fter clercutting, mngroves hrdly ever revegette, nd re considered nutrient-deficient ecosystems ecuse they contin low levels of N nd P. This pprent nutrient deficiency notwithstnding, these ecosystems flourish with no ovious signs of nutrient deficiency. Nitrogen fixtion in mngrove sediment, in the rhizosphere, nd ssocited with eril roots (8,) my provide the nitrogen necessry for plnt growth, nd phosphte-soluilizing microorgnisms my supply plnts with sufficient mount of phosphorus (4). Other cteri tht might enhnce plnt growth y other mechnisms such s those orgnisms tht hve een shown to promote the growth of terrestril crop plnts (,6,7) re unknown in this ecosystem. It ws previously oserved tht mngrove seedlings usully grow etter fter inocultion with the dizotrophic filmentous cynocteri Microcoleus chthonoplstes (3,3). Bsed on this oservtion, it ws resoned tht mngrove seedlings might lso enefit y eing inoculted with plnt growth-promoting cteri (PGPB) (). Inocultion of xenic lck mngrove seedlings in sewter for eight dys with either the terrestril hlotolernt plnt growth-promoting cterium Azospirillum hlopreferens or A. rsilense produced hevy coloniztion of the root surfce. The coloniztion pttern ws different for the two strins. A. hlopreferens yielded minly single cells emedded in thick sheth, wheres A. rsilense produced primrily microggregtes. A. rsilense cells were nchored to the root surfces nd to themselves y network of firillr mteril. Both cteril strins survived in sewter (pprox. 4 cfu/ml) for more thn 3 dys, for 7 dys in sline wter (A. rsilense), nd colonized mngrove roots t high popultion density. A. hlopreferens ws etter root surfce colonizer, wheres the A. rsilense popultion ws greter throughout the entire root (). A mixed culture of the N -fixing Phyllocterium sp. nd the phosphte-soluilizing cterium Bcillus licheniformis improved nitrogen ( 5 N) incorportion in leves nd improved seedling development of lck mngroves (). These works re the initil stges of study designed to ssess the fesiility of using plnt growthpromoting cteri for the inocultion of mrine plnts for environmentl purposes. Sewter griculture is defined s growing slt-tolernt crops on lnd using wter pumped from the se for irrigtion (4). Becuse none of the top five plnt species consumed y mn cn tolerte high levels of slt, sewter griculture would only e fesile if slt-tolernt plnts tht yield useful products t levels high enough to justify the expense of pumping nd

2 trnsporting wter from the se could e cultivted. Our working hypothesis ws sed on the ssumption tht insted of reeding common high yield crop for slt tolernce, it my e esier to select nd domesticte wild plnts tht lredy hve high slt tolernce nd possess desirle crop chrcteristics. Inocultion with PGPBs my help to improve crop yields. Species of the shru-like hlophyte seweed Slicorni re grown widely in climtes rnging from temperte to tropicl. Slicorni igelovii is n nnul, lefless, fst growing, succulent hlophyte found long the secost of Sonor nd Bj Cliforni, Mexico. Becuse S. igelovii produces oilseeds nd high yield of folige, it is eing evluted s new forge nd oilseed crop for slt-wter nd sewter-irrigted griculture in the costl deserts of Mexico nd the USA (5). Bcteri with confirmed plnt growth-promoting cpilities hve not yet een isolted from Slicorni plnts. Some species of Azospirillum cn survive well in sewter when inoculted on mngrove seedling roots (). In ddition, severl potentil mrine PGPBs (N - fixing nd phosphte-soluilizing cteri) were isolted from mngrove seedlings (4). Inocultion of S. igelovii with eight species of hlotolernt PGPBs nd grown in sewter-irrigted pots under environmentl conditions ntive to the plnt s hitt, resulted in significnt plnt growth promotion y the end of the growing seson, 8- months lter. Sttisticl nlyses demonstrted tht inocultion with terrestril hlotolernt Azospirillum hlopreferens, mixture of two hlotolernt A. rsilense strins, mixture of mrine Virio esturinus nd, or mixture of mrine Bcillus licheniformis nd Phyllocterium sp. significntly incresed plnt height nd dry weight t the end of the seson. Some of the cteril strins lso incresed the numer of side rnches nd the length of the spikes. The cteri did not ffect the numer of seeds or their weight. Inocultion with the mngrove ssocited cynocterium Microcoleus chthonoplstes previously shown to hve positive effects on development of mngrove plnts (3,3) hd no effect on Slicorni plnt folige vriles (Fig. ). At the end of the growing seson, the nitrogen nd protein content of the plnt folige were significntly reduced y cteril inocultion, however, the nitrogen nd protein content of seeds significntly incresed. The phosphorus content in folige incresed significntly in plnts treted with ll these cteri with the exception of M. chthonoplstes, wheres the totl lipid content of folige incresed significntly only when plnts were inoculted with either mixture of A. rsilense strins or with M. chthonoplstes (Fig ). In three inocultion tretments, plmitic cid in seeds significntly incresed nd linoleic cid significntly decresed, improving oil qulity.

3 p <. p <.6 Numer of rnches Plnt height (mm) A B p < x -4 p <.9 p <.3 p < 7x -4 Noninoculted Inoculted Plnt dry weight (g) p < 7x -5 p <.5 p <. p <. p <.4 C D p <.3 p <.3 p <.6 p <.5 84 % Lenght of spike (mm) 34 % - 33 % 8 % 64 % 73 % 44 % 6 % % 44 % 53 % 5 % 47 % 88 % 5 % A. hlopreferens AU A. rsilense Cd + A. rsilense Sp-45 V. esturinus + P. myrsincerum M. chthonoplstes A. hlopreferens AU A. rsilense Cd + A. rsilense Sp-45 V. esturinus + P. myrsincerum M. chthonoplstes Fig.. Effect of inocultion with severl plnt growth-promoting cteri on vrious morphologicl chrcteristics of Slicorni igelovii plnts t the end of the growing seson. A) plnt height, B) dry weight, C) numer of rnches, d) length of spike. Pirs of vlues (inoculted nd uninoculted) in ech sufigure tht differed significntly t P level denoted ove the pir re indicted y different lower cse letters. Verticl numers ove ech pir indicte significnt increse (or decrese), in percentge, of inoculted plnts s compred to uninoculted plnts. Brs represent SE.

4 Totl N (%) A Plnts p <.5 p <.3 - % - 3 % p <. - 7 % p <.9 - % Noninoculted Inoculted p <. - 9 % Totl N (%) 4 3 B Seeds p <.5x -4 p < x -7 p < x % 48 % 563 % p < 4x % p < x %.3 Totl P (mg/g). C Plnts p <.3 % p <.8 % p <.6 35 p <. p <.4 3 p < 7x % 3 % - 8 % Totl Lipids (%) 4 D Seeds - 7 % p <.46 8 % p <. - 5 % p <.4 94 % 5 A. hlopreferens AU A. rsilense Cd + A. rsilense Sp-45 V. esturinus + P. myrsincerum M. chthonoplstes A. hlopreferens AU A. rsilense Cd + A. rsilense Sp-45 V. esturinus + P. myrsincerum M. chthonoplstes Fig.. Effect of inocultion with severl plnt growth-promoting cteri on the chemicl composition of Slicorni igelovii folige nd seeds t the end of the growing seson. A) Totl N content of folige, B) totl N content of seeds, C) totl P content of folige, D) Totl lipid content of seeds. Pirs of vlues (inoculted nd uninoculted) in ech sufigure tht differed significntly t P level denoted ove the pir re indicted y different lower cse letters. Verticl numers ove ech pir indicte significnt increse (or decrese), in percentge, of inoculted plnts s compred to uninoculted plnts. Brs represent SE. Asence of r in ny column indictes negligile SE.

5 This study demonstrtes the fesiility of using cteri to promote the growth of hlotolernt plnts cultivted for forge nd seed production in sewter-irrigted griculture. Acknowledgments Y. Bshn prticipted in this study in memory of the lte Mr. Avner Bshn from Isrel. This study ws supported y Consejo Ncionl de Cienci y Tecnologí (CONACyT), Mexico, contrcts # 66-B nd # 836-B, y the Bshn Foundtion (to YB) nd y the Nturl Science nd Engineering Reserch Council of Cnd (to BRG). References. Bshn, Y., nd Holguin, G Azospirillum-plnt reltionships: environmentl nd physiologicl dvnces (99-996). Cn. J. Microiol. 43: 3-.. Bshn, Y., nd Holguin, G Proposl for the division of Plnt Growth-Promoting Rhizocteri into two clssifictions: iocontrol-pgpb (Plnt Growth-Promoting Bcteri) nd PGPB. Soil Biol. Biochem. 3: Bshn, Y., Puente, M.E., Myrold, D.D., nd Toledo, G In vitro trnsfer of fixed nitrogen from dizotrophic filmentous cynocteri to lck mngrove seedlings. FEMS Microiol. Ecol. 6: Boyko, H Slt-wter griculture. Sci. Am. 6: Glenn. E.P., O'Lery, J.W., Wtson, M.C., Thompson, T.L., nd Kuehl, R.O. 99. Slicorni igelovii Torr.: n oilseed hlophyte for sewter irrigtion. Science 5: Glick, B.R The enhncement of plnt growth y free-living cteri. Cn. J. Microiol. 4: Hllmnn, J., Qudt-Hllmnn, A., Mhfee, W.F., nd Kloepper, J.W Bcteril endophytes in griculturl crops. Cn. J. Microiol. 43: Hicks, B.J., nd Silvester, W.B Nitrogen fixtion ssocited with the New Zelnd mngrove (Avicenni mrin (ForsK.) Vierh. vr. resinifer (Forst. F) Bkh). Appl. Environ. Microiol. 49: Holguin, G., Bshn, Y., Mendoz-Slgdo, R.A., Amdor, E., Toledo, G., Vzquez, P., nd Amdor, A L microiologi de los mnglres, osques en l fronter entre el mr y l tierr. Cienci y Desrrollo 5 (no.44): Potts, M Nitrogen fixtion (cetylene reduction) ssocited with communities of heterocystous nd non-heterocystous lue-green lge in mngrove forests of Sini. Oecologi. 39: Puente, M.E., Holguin, G., Glick, B.R., nd Bshn, Y Root-surfce coloniztion of lck mngrove seedlings y Azospirillum hlofreferens nd Azospirillum rsilense in sewter. FEMS Microiol. Ecol. 9: Rojs, A., Holguin G., Bshn Y., nd Glick B.R.. Mutulism etween Phyllocterium sp. (N -fixer) nd Bcillus licheniformis (P-soluilizer) from semirid mngrove rhizosphere. This volume. 3. Toledo, G., Bshn, Y., nd Soeldner, A In vitro coloniztion nd increse in nitrogen fixtion of seedling roots of lck mngrove inoculted y filmentous cynocteri. Cn. J. Microiol. 4: - 4. Vzquez, P., Holguin, G., Puente, M.E., Lopez-Cortes, A., nd Bshn, Y.. Phosphtesoluilizing microorgnisms ssocited with the rhizosphere of mngroves growing in semirid costl lgoon. Biol. Fertil. Soils. 3: