EFFECTS OF NACL ON PLANT GROWTH, ROOT ULTRASTRUCTURE, WATER CONTENT, AND ION ACCUMULATION IN A HALOPHYTIC SEASHORE BEACH PLUM (PRUNUS MARITIMA)

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1 Pk. J. Bot., 50(3): , EFFECTS OF NACL ON PLANT GROWTH, ROOT ULTRASTRUCTURE, WATER CONTENT, AND ION ACCUMULATION IN A HALOPHYTIC SEASHORE BEACH PLUM (PRUNUS MARITIMA) LI-MIN WANG 1, XIAO-LI BU 2,3,*, JIN-LIN CHEN 2, DONG-FENG HUANG 1 AND TAO LUO 1 1 Deprtment of Soil nd Fertility, Fujin Ademy of Agriulturl Sienes, Fuzhou, Fujin , Chin, 2 Key Lortory of Eology, Fulty of Forest Resoures nd Environmentl Siene, Nnjing Forestry University, Nnjing, Jingsu , Chin 3 Fulty of Siene, Nnjing Forestry University, Nnjing, Jingsu , Chin * Corresponding uthor s emil: g898@126.om Astrt A pot ulture experiment ws onduted to evlute the effet of NCl on the growth, root ultrstruture, wter ontent, nd ion distriution in two - yer - old eh plum (Prunus mritim) seedlings. The seedlings were sujeted to different levels of NCl ddition (0, 50, nd 150 mm) for 120 dys under nturl onditions. Under high slinity (150 mm NCl), the ultrstruture of root ells in P. mritim showed the erliest sign of slt injury: inluding prtil fuzzy nuler memrne nd plsm memrne invgintion in the root ells of P. mritim. The root ells were unffeted y low slinity (50 mm NCl). Their root ells exhiited omplete kryothe, ovious nuleolus, numerous orgnelles, nd norml ell wll struture. However, P. mritim mintined higher wter ontent in plnt tissues under slinity onditions ompred with tht of the ontrol. Menwhile, the slt - treted seedlings lso mintined high onentrtions of C 2+, Mg 2+, nd K + in lef tissues. Furthermore, high slinity led to n inrese in K + /N +, C 2+ /N + nd Mg 2+ /N + seletivity rtios from stems to leves in P. mritim seedlings. In ddition, the growth rte, fresh nd dry weights of P. mritim were signifintly promoted y low slinity, wheres the growth prmeters were unffeted or even deresed t high slinity ompred to tht of the ontrol. The results indited tht low slinity hd positive effet on the growth of P. mritim y keeping the norml ultrstruture of root ells nd inresing the uptke of C 2+, Mg 2+, nd K + ions, espeilly in lef tissues. The negtive effet of high slinity on plnt growth ould e meliorted to some extent y inresing wter ontent in leves nd seletive trnsport of K +, C 2+ nd Mg 2+ from stems to leves in P. mritim seedlings. Key words: Beh plum; Root ell ultrstruture; Growth rte; Ion trnsporttion; NCl. Introdution Soil slinity ours minly long worldwide osts or in rid nd semi-rid regions with 3.1% ( hetres) of the totl lnd re of the world (Seti et l., 2013). It is one of the mjor environmentl stresses tht dversely ffets plnt growth nd iomss prodution due to the osmoti or ioni stresses, or omintion of oth stresses indued y high NCl - slinity (Hjiolnd et l., 2014; Cunh et l., 2016; Yrsi et l., 2017). Menwhile, the world popultion will expnd to out eight illion people in 2030, with onomitnt inrese in griulturl produts. Providing for these needs will require its expnsion into mrginl unprodutive slt-ffeted lnds. The use of hlophytes, espeilly woody plnts, is the most ost-effetive strtegy for sline soil remedition. Given tht NCl is the most widespred slt in nture, mny hlophytes hve evolved vrious mehnisms inluding ion homeostsis nd n inrese in the intke of wter for the dpttion of plnts to high slinity (Mimiti et l., 2014; Isl et l., 2014; Vijyn et l., 2003). Bsed on these mehnisms, hlophytes n e tegorized into three groups: euhlophytes - lrge mounts of N + nd Cl ions sor nd umulte in lef vuoles, exluders umulte N + nd Cl ions in root tissues, nd export these ions from the root ells k to the soil, nd ondutors - serete the sored ions y glnds or ldders (Jouyn, 2012). Numerous studies hve shown tht gret differenes in the slt response exist mong the different speies (Mimiti et l., 2014; Boughlle et l., 2009; Isl et l., 2014). Vijyn et l., (2003) suggested tht plnt growth of modertely slttolernt mulerry ws enhned under low slinity ut inhiited t high slinity. A different result ws reported y Mimiti et l., (2014), who indited tht plnt growth of Elegnus oxyrp ws unffeted y low slinity nd deresed with inresing slinity. Reently, lthough slt tolerne is investigted in mny rops (Asm et l., 2015; Huyen et l., 2015), the ellulr responses in the roots of woody plnts to high slinity remin lrgely unknown. P. mritim is very slt-tolernt shru of ostl plnt ommunities ross North Ameri. Moreover, it eomes populr nd widespred euse of its prolifi loom, prized fruit, nd the dpttion to sline environments. Currently, P. mritim hs een developed s new multipurpose rop for ostl eh in the world. Thus severl ttempts hve een mde to ring this wild fruit tree into ultivtion nd to mke use of its resistne to slt stress for the stilistion nd rehilittion of degrded sline lnd (Uv, 2004; Zi et l., 2012). Reent studies hve foused on fruit prodution nd the use-effet reltionship etween the eril prts nd the slt tolerne mehnism in P. mritim (Uv & Whitlow, 2007; Zi et l., 2012). Nevertheless, little is known out how slinity ffets its roots, whih diretly suffer from soil slinity. Thus, root trits, espeilly the root ultrstruture, should e more sensitive to slt stress. Furthermore, the ultrstruturl hnges in root ells of plnts would lso disrupt the uptke nd trnsport of wter nd ion in

2 864 LI-MIN WANG ET AL., plnts s result of growth rrest nd ell deth under slinity onditions (Lmers & Venekls, 2006; Russell & Clrkson, 2016). Menwhile, the seedling stge is usully the slt-sensitive hypertension phse in woody plnts. For this reson, young seedlings represent vlule mteril for the detetion of the erly response of plnts to slt. Our min hypothesis ws, therefore, slt stress would ffet the ultrstruture in root ells of P. mritim seedlings, nd thus resulting in ltered ion seletivity or wter ontent in plnt orgns, with onsequent growth redution in the seedlings. To test the hypothesis, this study imed to determine the effets of low (50 mm) nd high (150 mm) slt onentrtions on root ultrstruture, ion distriution, wter sttus, nd plnt growth t the seedling stge nd to evlute the reltive signifine of these trits imprting slt tolerne in P. mritim. Mterils nd Methods Plnt mterils nd growth onditions: An experiment ws onduted using ompletely rndomized design with 3 replites per tretment in erly April 2010 under nturl onditions t the Agriulturl Reserh Sttion of Nnjing Forestry University, Jingsu, Chin (118 48' E, 32 04' N). This study re hs sutropil humid monsoon limte with the verge nnul preipittion of 1,274 mm, the men nnul ir temperture of 16.2 o C, nd the reltive humidity of 76%. Two-yer-old P. mritim seedlings were trnsplnted into plsti pots (23 m in dimeter nd 28 m in depth) ontining 15 kg of sndy lom soil (ph = 6.88), g kg -1 of orgni mtter, 0.64 g kg -1 of totl N, mg kg -1 of ville K nd 4.10 mg kg -1 of ville P. On the 15th dy fter potting, 1000 ml per pot of different NCl solutions (0, 50, nd 100 mm) ws diretly pplied every other dy. The seedlings were hrvested fter 120-dy tretment. Growth prmeters nd wter ontent: The plnt height of three rndomly seleted seedlings under eh tretment ws mesured with steel tpe t the eginning (Dy 0, orresponding to 15th dy fter potting, t 1) nd t the end of tretment (Dy 120, orresponding to the 135th dy fter potting, t 2). Reltive growth rtes of height, then, were lulted y (h 2 - h 1)/(t 2 - t 1), where h 1 nd h 2 re the heights of the seedlings t times t 1 nd t 2, respetively. Control nd slt - treted plnts were olleted nd seprted into leves, stems nd roots fter 120 dys of slt-tretment. The different plnt prts were wshed with the deionized wter nd dried with towels efore the fresh weight (FW) ws determined. Dry mss (DM) ws mesured fter the plnt prts were oven dried t 105ºC for 15 min nd then t 70ºC till onstnt weight. Wter ontent (WC) of those tissues ws lulted, using the formul desried in Liu et l., (2016): WC FW DM DM 100 Eletron mirosopy: Root smples of pproximtely 2 mm length were ut with rzor lde in the root tips (<2 m), nd fixed with 4% glutrldehyde in 0.1 M phosphte uffer (ph 7.2) for 4 h. After eing wshed three times with the uffer, the root tip ws postfixed for 2 h with Os0 4 (2%, ph 7), dehydrted in grded etone series (30%, 50%, 70%, 90%, 100% [v/v]; 10 min eh step) nd emedded in Spurr's resin (Spurr, 1969). The resin ws polymerized t 35 C for 24 h, 45 C for 24 h, nd 60 C for 12 h, respetively. The emedded loks were setioned using n LKB Ultrotome I. The ultrthin setions were piked up on opper grids nd doule-stined with urnyl ette nd led itrte. The ultrstruture of the root ells of P. mritim ws oserved nd photogrphed with Hithi H-600 trnsmission eletron mirosope (Hithi Ltd., Tokyo, Jpn). Ion nlyses: The oven-dried roots, stems nd leves were ground. The ground smples (1 g eh) were digested in the mixture of HNO 3 nd HClO 4 (3:1, v/v) for tion nlyses. The N +, K +, C 2+ nd Mg 2+ ion ontents in extrts from plnt tissues were mesured y using n tomi sorption spetrophometer (AAS) (Unim Solr32, USA). In ddition, 250-mg tissue smple ws extrted in the mixture of 900 ml deionized wter, 100 ml 10 % CH 3COOH, nd 6.4 ml 0.1 M HNO 3. Cl - ontent in the extrt ws determined y titrtion with AgNO 3 (TDMFC, 1991). These ion (Cl -, N +, K +, C 2+, nd Mg 2+ ) ontents were expressed s mg g -1 DM. The seletivity of ion trnsport for K +, C 2+ nd Mg 2+ over N + (S K,N, S C,N nd S Mg,N) ws estimted using the following formul (Gori et l., 2010), where K, C, Mg nd N re the ontents of these ions in different orgns, respetively. K, C or Mg N shoot K, C or Mg N root K, C or Mg N lef K, C or Mg N shoot Sttistil nlyses: Vlues re shown s the mens ± SD. One-wy nlysis of vrine followed y Dunn s multiple rnge test ws used to determine whether the differenes etween the fertiliztion types were signifint. The signifine threshold ws t p<0.05. These nlyses were onduted with SAS Results Effet of NCl on growth prmeters in P. mritim seedlings Root ultrstruture: A ompt ell in the roots of ontrol plnts exhiited omplete kryothe, finely grnulr nd evenly distriuted hromtin, ovious nuleolus, numerous orgnelles, mylse - rih strhes, nd norml ell wll struture (Fig. 1A). The ultrstruture of the root ells in P. mritim ws unffeted y low slinity (Fig. 1B, D). However, the ultrstruture of root ells of P. mritim sujeted to high slinity showed derese in hromtin density nd strh ontent ompred with those of ontrol plnts (Fig. 1C, E). Moreover, orgnelle degrdtion ws oserved under high slinity onditions (Fig. 1C, E).

3 EFFECTS OF NACL ON BEACH PLUM SEEDLINGS 865 Fig. 1. The ell ultrstruture of Prunus mritim roots grown under different levels of NCl in irrigtion wter of 0 (A), 50 (B, D), nd 150 mm (C, E) for 120 dys. CW - ell wll; IS - interellulr spe; DM - degrded mteril; KA - kryotin; N - ell nuleus; NE - nuleolus; NM - nuleus memrne; S - strh; V - vuole. Tle 1. Effet of NCl on morphologil hrters of P. mritim seedlings fter 120 dys of tretment. Fresh weight /g plnt -1 Dry weight /g plnt -1 Growth rte Root Stem Lef Root Stem Lef /mm dy ±1.42() 25.26±1.69() 5.46±0.27() 14.62±1.16() 15.81±0.42() 2.33±0.13() 0.38± ±1.53() 25.35±1.70() 12.54±0.66 () 17.50±1.34() 15.33±0.76 () 5.03±0.20 () 0.82± ±1.12() 20.42±1.49() 5.98±0.33 () 9.89±0.23 () 11.70±0.54 () 2.44±0.15 () 0.37±0.07 Vlues (mens ± SD) with dissimilr lower-se letters inside nd outside the prentheses re signifintly different etween tissues or slinities t p<0.05 y Dunn s multiple rnge test, respetively Plnt growth rte, fresh nd dry mtter, nd wter ontent: Plnt growth ws signifintly promoted y low slinity, wheres it ws unffeted y high slinity ompred to tht of the ontrol (Tle 1). Fresh or dry mtter yields in roots, stems, nd leves of P. mritim were generlly inresed t low slinity, while the yields ws unffeted or even deresed y high slinity ompred with those in the ontrol plnts (Tle 1). In ddition, the fresh nd dry weights in tissues were rnked s follows: stem > root > lef in high slinity, nd the dry weight t low slinity ws in the order: root > stem > lef (Tle 1). Wter ontent in leves, stems nd roots ws generlly inresed with inresing slinity (Tle 2). Besides, wter ontent ws signifintly higher in leves thn tht in shoots nd roots of P. mritim (Tle 2). Effet of NCl on ion distriution in individul tissues of P. mritim seedlings Contents of Cl -, N +, K +, C 2+, nd Mg 2+ : The ontent of Cl - nd N + ws signifintly (p<0.05) greter in NCltreted plnts thn tht in the ontrol ones (Tle 3). Additionlly, P. mritim seedlings generlly umulted more Cl - nd N + in the leves nd roots thn those in the stems (Tle 3). Moreover, P. mritim would preferentilly tke up K +, prtiulrly C 2+ over toxi ions suh s N + nd Cl in leves, stems nd roots under sline onditions (Tle 3). Seletive trnsport oeffiients nd rtios of K + /N +, C 2+ /N +, nd Mg 2+ /N + : Slinity used mrked redutions in K + /N +, C 2+ /N +, nd Mg 2+ /N + rtios in

4 866 LI-MIN WANG ET AL., roots nd stems, nd Mg 2+ /N + rtios in leves of P. mritim (Tle 4). In ddition, the C 2+ /N + rtio ws higher thn K + /N + nd Mg 2+ /N + rtios in the tissues of P. mritim (Tle 4). The seletive trnsport oeffiients of K + /N +, C 2+ /N +, nd Mg 2+ /N + from stems to leves were generlly inresed with inresing slinity (Fig. 2D-E). There were lso higher seletive trnsport oeffiients for K + /N +, C 2+ /N +, nd Mg 2+ /N + from roots to stems in P. mritim seedlings t low slinity while lower seletivity oeffiients t high slinity thn those of the ontrol, respetively (Fig. 2A-C). Tle 2. Effet of NCl on wter ontent in roots, stems nd leves of P. mritim seedlings fter 120 dys of tretment. NCl Wter ontent/% (mm) Root Stem Lef ±2.11 () 59.77±3.04 () ±4.03 () ±2.50 () 65.36±3.17 () ±4.12 () ±3.09 () 74.53±3.08 () ±4.06 () Vlues (mens ± SD) with dissimilr lower-se letters inside nd outside the prentheses re signifintly different etween tissues or slinities t p<0.05 y Dunn s multiple rnge test, respetively Tle 3. Effet of NCl on the ontents of Cl -, N +, K +, C 2+, nd Mg 2+ (mg g -1 DW) in roots, stems nd leves of P. mritim seedlings fter 120 dys of tretment. Root Stem Lef Cl ±0.02() 0.18±0.01() 1.43±0.02() ±0.03() 1.20±0.02() 1.72±0.03() ±0.07() 1.97±0.03() 5.97±0.06() N ±0.01() 0.11±0.01() 0.52±0.07() ±0.06() 0.19±0.02() 0.54±0.05() ±0.23() 1.55±0.14() 2.31±0.26() K ±0.11() 1.51±0.09() 6.76±0.44() ±0.04() 1.42±0.02() 6.77±0.38() ±0.05() 1.30±0.02() 6.76±0.40() C ±0.39() 6.75±0.41() 11.70±0.54() ±0.36() 9.70±0.51() 12.07±0.48() ±0.35() 8.45±0.46() 12.31±0.44() Mg ±0.03() 1.12±0.04() 1.64±0.51() ±0.03() 1.15±0.02() 1.65±0.07() ±0.05() 1.08±0.02() 1.66±0.06() Vlues (mens ± SD) with dissimilr lower-se letters inside nd outside the prentheses re signifintly different etween tissues or slinities t p<0.05 y Dunn s multiple rnge test, respetively. Arevitions: DW, dry weight Disussion We found tht there were no signifint hnges in root ells of P. mritim t low slinity ompred with those of the ontrol (Fig. 1A, B, D). However, under high slinity, there were umulted degrdtion produts in root ells of P. mritim, in whih orgnelle degrdtion ws ongoing, nd nuler hromtin ondenstion ws inresed (Fig. 1C, E). In ddition, high slinity used more serious dmge to root ells of Frxinus Amerin, suh s ytoplsmi gglomertes, ovious plsmolysis, nd orgnelle degrdtion (Yng et l., 2009) in omprison to those of P. mritim (Fig. 1C, E). These results suggested tht P. mritim ws more tolernt to slt stress thn F. Amerin. Menwhile, this might e lso ompnied y differenes in ion distriution, wter sttus, nd iomss umultion in the tissues of P. mritim (Tles 1, 2, 3). An inrese in the growth rte of P. mritim seedling responding to low slinity ws oserved (Tle 1). This result is in greement with tht of Nguyen et l., (2015) in the slt-tolernt mngrove, Avienni mrin under slinity onditions, inditing tht low slinity hd stimulting effet on plnt growth in hlophytes. In ontrst, growth redution ws found in non-tolernt pomegrnte exposed to slinity (Khyyt et l., 2014). Those findings indited tht plnts showed diversity of growth responses to inresing slinity euse of the disrepnies in slt tolerne of plnt speies, the slt level nd exposure time. Similrly, lef fresh nd dry weight of P. mritim ws stimulted y low slinity ut unffeted y high slinity (Tle 1). In ddition, fresh nd dry weight of roots inresed t low slinity while deresed t high slinity ompred with tht of the ontrol (Tle 1). It is known tht high NCl - slinity my dversely ffet photosynthesis, whih is prerequisite for iomss prodution (Aideen et l., 2014; Koyro et l., 2013), euse Cl - toxiity disrupts the norml eletron flow to photosystem II, nd thus uses the eletron lekge, inreses the genertion of retive oxygen speies nd indues oxidtive stress (Friduddin et l., 2013). Moreover, the iomss of stems ws generlly higher thn tht in roots or leves (Tle 1). The results re onsistent with the findings from studies of Pterorpus offiinlis nd pisthio (Dulormne et l., 2010; Hjiolnd et l., 2014), nd Elegnus oxyrp seedlings (Mimiti et l., 2014). In generl, the slttolernt speies showed etter growth performne t low slinity thn tht under high slinity. Tle 4. Effet of NCl on the rtios of K + /N +, C 2+ /N +, nd Mg 2+ /N + in roots, stems nd leves of P. mritim seedlings fter 120 dys of tretment. Root Stem Lef K + /N ±1.13() 13.73±1.03() 1±1.26() ±0.11() 7.47±0.54() 12.54±1.27() ±0.01() 0.84±0.05() 2.93±0.16() C 2+ /N ±2.25() 61.36±3.49() 22.50±1.75() ±1.31() 51.05±3.22() 22.35±1.46() ±0.24() 5.45±0.37() 5.33±0.44() Mg 2+ /N ±0.65() 10.18±1.15() 3.15±0.23() ±0.07() 6.05±0.45() 3.06±0.19() ±0.03() 0.70±0.04() 0.72±0.06() Vlues (mens ± SD) with dissimilr lower-se letters inside nd outside the prentheses re signifintly different etween tissues or slinities t p<0.05 y Dunn s multiple rnge test, respetively

5 SK,N SC,N SMg,N SK,N SC,N SMg,N EFFECTS OF NACL ON BEACH PLUM SEEDLINGS (A) (B) (C) 4.00 (D) (E) (F) Fig. 2. Effet of NCl on seletive trnsport oeffiients for (A) K + /N +, (B) C 2+ /N +, (C) Mg 2+ /N + from roots to stems, nd (D) K + /N +, (E) C 2+ /N +, (F) Mg 2+ /N + from stems to leves in P. mritim seedlings fter 120 dys of tretment. Vlues (mens ± SD) with dissimilr lower-se letters re signifintly different etween slinities t p<0.05 y Dunn s multiple rnge test. The wter ontent in the root, shoot nd lef of P. mritim ws generlly inresed with the inrement of slinity (Tle 2). Additionlly, wter ontent in leves of P. mritim ws higher thn tht in stems or roots (Tle 2), suggesting tht wter trnsport from roots to leves ws not inhiited y slinity. Therefore, P. mritim tended to dilute n exess of Cl - nd N + ions in their leves nd promote photosynthesis with the inrese of wter ontent, whih might e n importnt trit tht ws required to overome slinity - indued redution in growth of P. mritim plnts (Wise et l., 2006). Tht ontrdits the findings of Khyyt et l., (2014), who reported derese in wter ontent in leves of Mlse-Sveh nd Shishe-K pomegrntes under slt stress. These results lso differ from those reported y Mimiti et l., (2014), in whih wter ontent in leves under slinity remined unhnged in Elegnus oxyrp seedlings. These differenes in plnt wter sttus might e minly relted to the time of slt stress, the slt onentrtion, nd plnt slt tolerne. The higher Cl - nd N + ontents in leves of P. mritim were oserved under slt tretment (Tle 3). A similr onlusion ws drwn y Storey et l., (2003). This umultion of N + nd Cl ions might e doule-edged sword. On the one hnd, it ould stimulte osmoti djustment y lowering the osmoti potentil t low slinity; on the other hnd, the exessive umultion of those toxi ions in lef tissues hs simultneous detrimentl effets on photosynthesis nd plnt growth despite osmoti djustment in tissues t extreme slinity (Benzrti et l., 2012). In prtiulr, n inrese in the umultion of N + n ompetitively prevent the uptke of the ountertions (K +, C 2+, nd Mg 2+ ) through nonseletive tion hnnels (Pottosin & Dorovinsky, 2014), thus resulting in n insuffiient mount of these essentil minerl ions neessry for plnt growth nd development (Desingh & Kngrj, 2007). However, our results showed tht the inrese in N + ontent ws not ompnied y derese in the ontents of K +, C 2+ nd Mg 2+ in leves of P. mritim (Tle 3). Contrrily, lef K +, C 2+ nd Mg 2+ ontents were inresed with inresing slinity (Tle 3). The umultion of these inorgni ions in plnt tissues might e used s the osmoti to sor wter from sline soils y lowering their osmoti potentil, whih ws entrl feture of the slt tolerne of P. mritim. Interestingly, Kopittke (2012) reported tht C 2+ ould not improve growth of slt-stressed plnts in the sene of K +, suggesting tht C 2+ did not diretly redue N + toxiity, ut rther enhned the ility to retin K + in lleviting NCl-indued slt stress on plnt growth. Menwhile, we found tht P. mritim umulted high mounts of N + nd Cl - in their leves, ut oth ions hd no visile toxi effets on plnt growth (Tle 3). This ould e possily explined y the ft tht N + nd Cl were omprtmentlized in the vuole of plnt ells (Deez et l., 2006). Conversely, two slt tolernt Mls-e-Sveh nd Shishe-K pomegrntes (Khyyt et l., 2014) s well s Sum Speies, Rhus trilot (Liu et l., 2013), hd reltively low lef N + nd Cl - ontents due to retention of oth ions in shoots nd roots of hlophytes under slt stress, therey preventing their trnslotion into the leves to llevite the slt - indued injury, whih is typil of hlophyti speies well dpted to slinity. Shl & Munns

6 868 LI-MIN WANG ET AL., (2012) reveled tht hlophytes hve developed different strtegies to ope with slt stress, inluding Cl - nd N + exlusion nd/or the omprtmentliztion of oth ions in lef vuoles. Overll, our findings suggested tht the slt tolerne mehnism in P. mritim should elong to the ltter se, ut the preliminry onlusion ws further verified t moleulr levels. The mintenne of high tissue K + /N +, C 2+ /N +, nd Mg 2+ /N + rtios is lso n importnt hrteristi of slt-stress dpttion (Wei et l., 2003). However, these rtios in roots, shoots nd leves of P. mritim signifintly (p<0.05) deresed with inresing slinity (Tle 4). Hene, the mssive umultion of N + nd Cl - ions in plnt tissues my use ion imlne. Additionlly, the seletive trnsport oeffiients for K + /N +, C 2+ /N +, Mg 2+ /N + from roots to stems in P. mritim seedlings ws inresed with inresing slinity nd then deresed t high slinity (up to 250 mm), wheres the seletive trnsport oeffiients for these rtios from stems to leves ws inresed with inresing slinity (Fig. 2A-F). Thus high slinity led to the restrition on the seletive trnsport of K +, C 2+ nd Mg 2+ from roots to stems ut promotion on their seletivity from stems to leves. As onsequene, the ontents of K +, C 2+ nd Mg 2+ in stems would e redued nd use growth inhiition of P. mritim with muh longer period of high slinity. In onlusion, our results showed P. mritim ould generlly protet themselves from slt-indued osmoti nd ioni stresses y mintining higher seletive trnsporttion of K +, Mg 2+, espeilly the enrihment of C 2+ in leves t the seedling stge s distintive trit of slt tolerne speies. 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