Chloride Nutrition Regulates Water Balance in Plants

Transcription

1 XII Portuguese-Spnish Symposium on Plnt Wter Reltions Chloride Nutrition Regultes Wter Blne in Plnts Frno-Nvrro JD 1, Brumós J, Rosles MA 1, Vázquez-Rodríguez A 1, Sñudo BJ 1, Díz- Rued P 1, Rivero C 1, Tlón M, Colmenero-Flores JM 1 1 Instituto de Reursos Nturles y Agroiologí de Sevill (IRNASE). Consejo Superior de Investigiones Científis (CSIC). Avd. Rein Meredes 1, 11-Sevill, Spin. Instituto Vlenino de Investigiones Agrris. Centro de Genómi. Crreter Mond - Náquer, Km., Mond (Vleni), Spin. e-mil: hemf@irnse.si.es ABSTRACTS Cl - is strnge mironutrient sine tul Cl - onentrtion in plnts is out two orders of mgnitude higher thn the ontent required s essentil mironutrient. This umultion requires high ost of energy, nd sine Cl - is mjor osmotilly tive solute in the vuole, we propose tht Cl - plys role in the regultion of wter lne in plnts. We show here tht, when umulted to mronutrient levels, Cl - speifilly regultes lef ell elongtion nd wter lne prmeters, improving wter reltions t oth the lef tissue nd the whole plnt levels, inresing drought resistne in higher plnts. INTRODUCTION Chloride (Cl - ) is one of the 1 elements essentil for plnt growth. Beuse it is supposed to e needed in smll quntities for helthy growth of higher plnts (<5-1 mm in the nutrient medi), Cl - ws desried s mironutrient (Johnson et l., 1957; Terry, 1977). Usully non-hlophyti plnts present ritil defiieny ontents elow, mg/g shoot dry weight (reviewed in Flowers, 19; Mrshner, 1995; White nd Brodley, 1), under whih defiient plnts show signifint derese in lef re s result of redution in ell division rtes (Terry, 1977). However tul Cl - onentrtion in plnts is typil of the ontent of mronutrient (1- mg/g, out 5-3 times higher thn the ontent required s essentil mironutrient; Mrshner, 1995; Brumós et l., 1). This umultion requires high ost of energy (Brumós et l., 1), nd sine Cl - is mjor osmotilly tive solute in the vuole (Flowers, 19), we hypothesize tht Cl - my regulte wter reltions nd drought resistne in higher plnts when umulted to mronutrient levels. MATERIALS AND METHODS Too plnts were grown under well-irrigted semi-hydroponi onditions sujeted to different nutritionl tretments onsisting on sl nutrient solution (BS) or BS supplemented with different slt omintions: Cl slts (); NO 3 slts (N); nd SO + PO 3- slts (). All tretments (, N nd ) ontined the sme onentrtion of hrgelning tions. Plnts were sujeted to two irrigtion tretments: optiml irrigtion

2 XII Portuguese-Spnish Symposium on Plnt Wter Reltions (Control, 1% of field pity), nd wter defiit, in whih pots were irrigted every two dys to % of field pity. Mterils nd methods re desried in Frno-Nvrro et l. (13,). Men vlues ± SE, n = -. Levels of signifine (ANOVA nd MANOVA test): P.5 (); P.1 () nd P.1 (). RESULTS AND DISCUSSION As it ws shown efore (Frno-Nvrro et l., 13,), no differenes of lef tions ontent (C +, Mg + nd K + ) were oserved mong, N nd tretments. Cl - is n essentil oftor in photosynthesis, ut the primry ftor involved in the redued growth under defiient ondition ws redued rte of ell division in the leves (Terry, 1977). We verified tht photosynthesis nd lef ell division rte were not impired in plnts sujeted to low Cl - tretments, demonstrting tht BS, or N tretments overed essentil mironutrient requirements of Cl - (Fig. 1A-B),. Plnt growth ws stimulted with NO - 3 nd Cl - tretments (Fig. 1D). As it ws expeted, NO - 3 -treted plnts showed the highest growth nd iomss euse of the importnt role of nitrogen in plnt growth nd development (Mrshner, 1995). Cl - -treted plnts showed progressively enhned growth with inresing onentrtions of Cl - from 1 mm (Fig. 1C). Wheres NO - 3 stimulted ell division (Fig. 1A) nd photosyntheti metolism (Fig. 1B), Cl - speifilly stimulted ell elongtion in the lef (Fig. ). This ws prtiulrly evident in epiderml ells (Fig A), signifintly more elongted in Cl - -treted plnts (Fig B), nd this effet ws progressively enhned with inresing onentrtions of Cl - (Fig C). Our working hypothesis ws tht Cl - nutrition in the millimolr rnge might speifilly improve the hydri stte of plnt tissues nd wter prmeters t the whole plnt level. In the lef, wter ontent ws speifilly stimulted y Cl - over in the millimolr rnge onentrtion (Fig. 3A). The higher lef tissue osmolrity oserved in Cl - -treted plnts reflets higher mount of osmotilly tive solutes per dry weight unit (Frno-Nvrro et l., 13,). This orreltes with more negtive lef osmoti potentil (Ψπ) in mture leves of plnts treted with Cl - in the millimolr rnge (Fig. 3B, 3E). It ws oserved tht pre-dwn lef turgor (Ψp) from Cl - -treted plnts ws signifintly higher thn tht from BS, nd N plnts (Fig. 3C), nd differenes were more evident t mid-dy (Fig. 3D). Osionlly, dult plnts treted with NO - 3 showed visul symptoms of turgor loss in the greenhouse t times of high evpotrnspirtion demnd (not shown), whih orrelted with turgor vlues lose to zero mesured t mid-dy (Fig. 3D). In plnts, the most importnt ftor regulting wter ontent is lef trnspirtion. Interestingly, plnts (from 1-5 mm) showed lower trnspirtion thn, N nd BS plnts, quntified s the reltive loss of fresh weight mesured in dethed leves (Fig. A). Redued trnspirtion of plnts ws onsequene of the lower stomtl ondutne (g s ) oserved in Cl - -treted plnts (Fig. B- 3

3 XII Portuguese-Spnish Symposium on Plnt Wter Reltions C), whih in turn determined lower onsumption of wter (Fig. D) nd higher wter use effieny mesured s totl plnt weight reltive to totl wter onsumption (WUE; Fig. E). When sujeted to wter defiit, Cl - plnts were le to keep higher lef turgor vlues ompred to (Fig. 5A). Cl - plnts presented signifintly higher A N (Fig. 5B), resulting in higher photosyntheti wter-use effiieny (WUEi; Fig. 5C); As onsequene, Cl - -treted plnts presented higher PSII quntum yield vlues long the wter defiit tretment (Fig. 5D), inditing more fvorle preservtion of PS-II integrity nd, therefore, etter ility of plnts to withstnd wter defiit. ACKNOWLEDGEMENTS This work ws supported y the Spnish Ministry of Siene nd Innovtion-FEDER grnt AGL9-339/AGR. REFERENCES Brumós, J., et l. (1). Cl- homeostsis in inluder nd exluder itrus rootstoks: trnsport mehnisms nd identifition of ndidte genes. Plnt, Cell & Environment 33, 1-7. Frno-Nvrro, J.D., et l. (13). Chloride nutrition: novel funtions in wter reltions. XI Simposio hispno-portugués de reliones hídris en ls plnts. IRNASE-CSIC, Sevill. Frno-Nvrro, J.D., et l. (13). Chloride nutrition t mronutrient levels regultes development, wter lne nd drought resistne in too plnts. Enviroment Workshop 13. UNIA-UMA-CSIC, Bez. Johnson C.M., et l. (1957) Plnt Soil,, Flowers, T.J. (19). Chloride s nutrient nd s n osmotium. In: Tinker B LA, ed. Advnes in plnt nutrition, Vol. 3. New York: Preger, Johnson, C.M., et l. (1957). Comprtive hlorine requirements of different plnt speies. Plnt Soil, Mrshner, H. (1995). Minerl Nutrition of Higher Plnts, nd ed. London: Ademi Press. Terry, N. (1977). Photosynthesis, growth, nd role of hloride. Plnt Physiology, White, P.J. & Brodley, M.R. (1). Chloride in Soils nd its Uptke nd Movement within the Plnt: A Review. Annls of Botny, Zimmermnn, D., et l. () A novel, non-invsive, online monitoring, verstile nd esy plnt-sed proe for mesuring lef wter sttus. Journl of Experimentl Botny 59,

4 Wter Content (%) Lef ψπ (-MP) Lef ψp (+MP) Lef ψp (+MP) Lef ψπ (-MP) Epiderml Cell Size (µm ) Lef epiderml ells (x1 ) Totl Dry Weight (g) Leves Dry Weight (g) XII Portuguese-Spnish Symposium on Plnt Wter Reltions A) B) C) D) 1 1 BS N Tretment (mm) BS N Fig. 1. Effet of Cl - nutrition on photosynthesis, ell division nd growth. (A) Cell division rte, quntified s the numer of epiderml ells per lef. (B) Effet on net Photosyntheti rte (A N ) mesured in fully expnded nd photosyntheti leves. (C) Totl plnt dry weight. (D) Leves Dry Weight. Dys fter sowing (DAS). A) B) C) Tretment (mm) Fig.. Effet of Cl - nutrition on ell elongtion. (A,C) Epiderml Cell Size. (B) Epiderml ell size oserved in mirosopy imges of lef epiderml impressions of -treted plnts (left) nd Cl - -treted plnts (right). A) B) C) D) E) Tretment (mm) BS N Fig. 3. Effet of Cl - nutrition on lef osmoti potentil nd turgor, nd wter ontent. (A) Lef Wter Content. (B,E) Mture Lef Osmoti potentil; (C,D) Mture Lef Turgor potentil; (B,C,E) Pre-dwn vlues; (D) Middy vlues BS N N Tretment (mm) 5

5 A N (μmol CO m -1 s -1 ) WUE i (μmol CO mol -1 H O) Fresh weight loss (%) g s normlized (%) WUE (gfw ml -1 ) XII Portuguese-Spnish Symposium on Plnt Wter Reltions A) B) C) D) E) BS N hours Fig.. Effet of Cl - nutrition on lef trnspirtion. (A) Fresh weight loss in dethed leves. (B,C) Stomtl ondutne; (D) wter onsumption relted to fresh iomss; (E) Integrted Wter Use Effiieny; 1 1 Tretment (mm) H O Consumed (ml g -1 FW d -1 ) Tretment (mm) Tretment (mm) A) B) C) D) TURGOR LOSS STOP WATERING REHYDRATION Control N Drought Fig. 5. Effet of Cl - nutrition on drought resistne. (A) Lef turgor mesurement using the mgneti lef pth lmp pressure proe (Zimmermnn et l., ). Red rrow indites stop wtering nd lue rrow indites rehydrtion. (B,C) 3-dys verged dt mesured from plnts sujeted to irrigtion tretments: (B) Net Photosyntheti rte (A N ); (C) Photosynteti Wter Use Effiieny. (D) PSII Effiieny or quntum yield (ф PSII ). Leled C (filled symols) orresponds to ontrol irrigtion, nd D (empty symols) orresponds to wter-defiit irrigtion. 1 1 N Control Drought