Journal of Environmental Biology September 2010, 31(5) (2010)

Transcription

1 Journl of Environmentl Biology Septemer, (5) () Triveni Enterprises, Luknow (Ini) For personl use only Free pper ownloe from: www. je.o.in Commeril istriution of this opy is illegl Genotypi vrition in Brssi june (L.) Czern. ultivrs in growth, nitrte ssimiltion, ntioxint responses n phytoremeition potentil uring mium stress Ash Shrm, Mnish Singer,, Snjy Dwivei, Suhkr Srivstv,4, R.D. Tripthi n Rn P. Singh* Deprtment of Biosienes, M.D. University, Rohtk - 4, Ini Deprtment of Environmentl Siene, B.B.A. University, Re Breliy Ro, Luknow - 6 5, Ini Eotoxiology n Bioremeition Group, Ntionl Botnil Reserh Institute, Luknow - 6, Ini 4 Funtionl Plnt Biology Setion, Nuler Agriulture n Biotehnology Division, FIPLY, Bhh Atomi Reserh Centre, Mumi , Ini (Reeive: Novemer, 8; Revise reeive: Novemer, 9; Aepte: Deemer, 9) Astrt: Four ultivrs of Brssi june i.e. TM-4, TM-, RH- n T-59 were sreene for see germintion n seeling growth up to 5 ys in the presene of.5-.5 mm mium (C). The exposure to C reue see germintion n seeling growth (root n shoot length n ry weight) in ll four ultivrs; the effet eing more severe in TM- n RH- thn in TM-4 n T-59 n t thn t 7 n 5. The ultivrs TM-4 n T-59, with higher tolerne to C toxiity, were selete for further nlysis inluing the estimtion of nitrte reutse (NR) n peroxise (POD) tivities, totl orgni nitrogen (TON), totl solule proteins, proline levels n C umultion. The NR tivity n totl solule proteins erese upon C exposure in onentrtion epenent mnner, wheres TON inrese signifintly in seelings upon C exposure. The tivity of POD n proline level inrese signifintly s ompre to the respetive ontrols. The level of C umultion ws higher in T-59 thn in TM-4. Therefore, T-59 ws foun to e the most tolernt ultivr to C thn other three ultivrs possily ue to etter pity to trnsport C in their vuolr sink. The vriety T-59, thus, ppers to e suitle for C phytoremeition. Key wors: Brssi june, Cmium, Growth, Phytoremeition PDF of full length pper is ville online Introution Cmium (C) is one of the most toxi hevy metls, whih is relese into the environment y nthropogeni pthwys e.g. mining n smelting, ispersl of sewge sluge, power sttions n C-rih phosphte fertilizers (Chney, 998). Its long persistene in the environment n umultion y foo-hin orgnisms mke it potentil environmentl hzr (Duk n Miller, 999; Ain et l., 7; Sihu et l., 8; Hsn et l., 9). The toxi effets of C on iologil systems hve een reporte extensively (i Toppi n Grielli, 999; Kirkhm, 6). Cmium is reporte to use hlorosis with stunte growth, ultrstruturl n physiologil mges (Vehi et l., 5; Prs, 995; Dinkr et l., 9; Chuhry n Shrm, 9), inhiit the iosynthesis of hlorophyll (Moin n Khn, 7), lter wter lne (Brelo n Poshenrieer, 99), erese tivity of vrious enzymes (Chuhry n Singh, ; Goui et l., ; Dong et l., 6; Mishr et l., 6) n interfere with generl n memrne physiology (i Toppi n Grielli 999; Nouiri et l., 6; Chuhry n Singh, ; Liu et l., ; Lin et l., 7). There re mny plnts, oth quti n terrestril, whih n umulte high level of the toxi metls in their tissues. Suh * Corresponing uthor: rnpsingh@hotmil.om plnts n e helpful to remove the pollutnts from soil n wter (Singh et l., 997,, 7) to reue their ontmintion; the tehnique is populrly known s phytoremeition. In reent times, Inin mustr viz., Brssi june (L.) Czern hs een one of the most stuie terrestril plnts for its potentility to extrt hevy metls from soil, fly-sh n seiments (Zhu et l., 999; Singh et l.,, 7; Qir et l., 4; Gupt n Sinh, 6). This plnt hs een emonstrte to e hyperumultor of C, is fst growing n possesses higher eril iomss thn mny other potentil metl umultors n hene, n e use s phytoremeitor (Singh et l., 7; Nouiri et l., 6). To hieve this gol, sreening high yieling ultivrs of Inin mustr suitle for the vrious grolimti zones n hving tolerne to hevy metls inluing C, is neee to evelop phytoremeition tehnology for northern Inin soil ontminte with C. The genotypi vrition in phytoremeition potentil of B. june ultivrs (Qir et l., 4; Moin n Khn, 7) hs een reporte. In ition, the use of Brssi plnts in the phytoremeition of C n other metls hs lso een emonstrte t fiel level or in simulte pot experiments (Ahme et l., ; Su n Wong, 4; Ishikw et l., 6). Thus, it seems worthwhile to sreen pproprite plnt ultivrs for tolerne n umultion of C, so tht the est ultivr e use for phytoremeition of C-pollute sites without ffeting growth n yiel of the rop. Journl of Environmentl Biology Septemer,

2 774 In this ontext, the present stuy ws plnne to stuy the responses of four ultivrs of B. june i.e. TM-, TM-4, T-59 n RH- uner C stress. Stress exerte y C to plnt growth ws mesure in terms of effets on the see germintion, shoot n root length n iomss (ry weight). Two ultivrs viz., TM-4 n T-59, whih were foun to hve greter tolerne to C, were further nlyze for totl orgni nitrogen, protein n proline ontents, nitrte reutse n peroxise tivities, n C umultion in C-expose seelings fter, 7 n 5. Mterils n Methos Sees of B. june L. v TM-4 n TM- were otine from, Plnt-Bioteh Division, Bhh Atomi Reserh Centre, Tromy, Mumi, n tht of ultivrs T-59 n RH- were purhse from the lol eler. Sees were sterilize in 7% ethnol for - min n wshe uner running tp wter, followe y istille wter till the lohol is remove. Thirty sterilize sees were put in eh petriplte on moist filter pper n wtere with 5% Hogln nutrient meium (Hogln n Arnon, 95) with/without C (,.5,. n.5 mm; prepre using the slt mium ette; E-Merk) for germintion. The numer of germinte sees ws ounte mnully fter 7. After germintion, seelings were trnsferre to smll ekers n were expose to ifferent onentrtions of C mintine in 5% Hogln nutrient meium for perio of, 7 or 5 uner ontrolle lortory onitions (5 hr photoperio using light intensity of 5 mmol m - s -, y/night temperture of 5± o C n reltive humiity of 55-75%). At eh hrvesting perio, plnts were wshe thoroughly with oule istille wter n were use for the nlysis of vrious prmeters. For mesurement of ry weight, seelings were rie in n oven for to onstnt weight n then weighe using n eletroni lne. The root n shoot lengths of the seelings were mesure using metri sle. The tivity of nitrte reutse (NR; EC.6.6.) in leves n roots ws ssye y in vivo metho given y Srivstv (975). For estimtion of orgni nitrogen (TON), the moifie miro Kjelhl metho ws use (Lng, 958). The protein ontent ws estimte y the metho of Brfor (976). For estimtion of peroxise (POD; EC...7) tivity in the plnt prts, the metho given y Putter (974) ws use n the proline ontent ws estimte following the metho y Btes et l. (97). For C estimtion, oven-rie seelings were igeste in HClO 4 :HNO (: v/v) t o C n then ilute with eminerlize wter. Cmium onentrtion ws etermine on Flme Atomi Asorption Spetrophotometer (GBC Avnt O, Austrli). The stnr referene mteril of C (E-Merk, Germny) ws use for the lirtion n qulity ssurne. Anlytil t qulity of C ws ensure through repete nlysis (n = 6) of EPA qulity ontrol smples (Lot TMA 989) n the results were foun to e within ±.79% of ertifie vlues. Reovery of C from the plnt tissues ws foun to e more thn 98.5%. The lnks were run in Shrm et l. triplite to hek the preision of the metho with eh set of smples. The etetion limit of C ws. ppm. The experiments were rrie out in rnomize lok esign. Two-wy nlysis of vrine (ANOVA) ws one on ll the t to onfirm the vriility of t n vliity of results, n Dunn s multiple rnge test (DMRT) ws performe to etermine the signifint ifferene etween tretments (Gomez n Gomez, 984). Results n Disussion Differentil effets of mium exposure on the germintion perentge n growth of four ultivrs of Brssi june: A signifint inhiition of see germintion ws oserve in ll vrieties in presene of C fter 7 (Tle ). A signifint eline in germintion perentge ws notie t.5 mm C in RH- n TM-, t. mm C in TM-4 while only t.5 mm C in T-59. The metl use ely in germintion. An inhiition of see germintion upon exposure to C hs lso een reporte in other plnts lso inluing Vii f n Sesmum inium (Bhrti n Singh, 994; Singh et l., 988,99; Bhrti et l., 996; Liu et l., ). Cmium exposure use signifint erese in the seelings length s funtion of the level n urtion of exposure (Tle ). After see sowing, the seeling length ws inhiite y out 75, 67, 66 n 55% in RH-, TM-, TM-4 n T-59, respetively t.5 mm C. After 7 n 5, erese in totl seeling length ws higher in RH- n TM- (up to 79-8%) thn in TM-4 n T-59 (up to 5-57%). In ll four vrieties, erese in root length ws more severe thn tht in the shoot length. Dry weights of ll four vrieties were lso signifintly reue upon exposure to C for, 7 n 5 fter sowing (Tle ). In seelings, reution in ry weights ws out 8% in RH- n TM- while it ws out 5% in TM-4 n T-59. With n inrese in urtion, reution in ry weights erese in ll vrieties. After 5, reution in ry weights in RH- n TM- ws out 55-6% while in TM-4 n T-59 it erese to out 4%. Similr to seeling length, the lowest reution in ry weigh ws notie in T- 59, while the mximum reution ws oserve in TM-. The most ommon effet of C toxiity in plnts hs een shown to e stunte growth, lef hlorosis n ltertion in the Tle - : Perentge of see germintion of B. june vrieties s lulte for 7 ol seelings in presene of mium Conentrtion % of see germinte (mm) T-59 TM-4 RH- TM- 79. ±.8 7. ±.9 8. ±. 86. ± ± ± ± ± ± ± ± ± ± ± ± ±.8 Dt represent the men ±S.E. (n = 9), ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,, n ) inite signifintly ifferent vlues (DMRT, p<.5) Journl of Environmentl Biology Septemer,

3 Response of Brssi june uner C stress 775 NRA (µmol NO min - g - f.wt.) NRA (µmol NO min - g - f.wt.) NRA (µmol NO min - g - f.wt.) Leves (C) Leves TON (mg g -.wt.) TON (mg g -.wt.) TON (mg g -.wt.) 4 4 (C) Leves Leves Fig. : Nitrte reutse tivity (NRA) of the vrious plnt prts of Brssi june seelings t, 7 n 5 (C) upon exposure to ifferent mium onentrtions. Vlues re men ± SD (n=). ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,,, n ) inite signifintly ifferent vlues (DMRT, p<.5) tivity of mny key enzymes of vrious metoli pthwys (i Toppi n Grielli, 999). The present results of the length n ry weights of the seelings inite tht vrietl ifferenes in response to C toxiity existe in four vrieties n the initil responses were not only linke not only with the genotype ut lso with the metl onentrtion (Singh et l., 988, 99). These results re in onformity with the stuy of Qir et l. (4) who lso emonstrte signifint eline in seeling height n iomss s funtion of C onentrtion. Seeling growth of other plnt speies hs lso een reporte to e inhiite vriously in the presene of hevy metls inluing C (Bhrti n Singh, 994; Bhrti et l., 996; Liu et l., ). The oserve growth reution my e ttriute to reue photosyntheti effiieny of the plnts Fig. : Totl orgni nitrogen (TON) ontent of the vrious plnt prts of Brssi june seelings t, 7 n 5 (C) upon exposure to ifferent mium onentrtions. Vlues re men ± SD (n=). ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,,, n ) inite signifintly ifferent vlues (DMRT, p<.5) upon C exposure (Hyt et l., 7; Moin n Khn, 7; Singh et l., 7). However, with n inrese in urtion some reovery over growth inhiition ws notie in ll four vrieties, whih might e linke to n inution of vrious efense strtegies s n ptive response inluing proly the synthesis of metl ining ligns, suh s phytoheltins (Slt et l., 995) n metllothioneins (Shfer et l., 997) n other stress responsive proteins likely the ntioxint enzymes (Hyt et l., 7). An upregultion of numer of genes in response to C exposure hs een oserve in B. june (Minglin et l., 5) inluing those of tlse, n importnt ntioxint enzyme of the ell (Mishr et l., 6) n ATP sulfurylse n APS reutse, the importnt enzymes of ysteine iosynthesis. In generl, TM-4 n T-59 were Journl of Environmentl Biology Septemer,

4 776 Shrm et l. Tle - : Seeling length (root + shoot) in, 7 n 5 ol B. june in the presene of mium Conentrtion B. june vrieties (mm) ol seelings (m + S.E.) 7 ol seelings (m + S.E.) 5 ol seelings (m + S.E.) T-59 TM-4 RH- TM- T-59 TM-4 RH- TM- T-59 TM-4 RH- TM-..7 ±..9 ±.5.8 ±..7 ±.6.9 ±.9.7 ± ±.44. ±. 4.9 ±.9 4. ±.8.9 ±.86. ±.7 () () () () ( ) (6.+5.6) (4.7+5.) ( ) (7.+7.7) ( ) ( ) (6.+7.).5. ±.5.8 ±.. ±.6.4 ±..5 ± ± ± ±.46. ±.57. ± ± ±.46 (5.4+5.) (5.+4.8) (.9+.4) (.5+.) (6.+6.) ( ) (.+.9) (.7+.7)..7 ±.8.6 ±.9. ±.7. ±.9 8. ± ±.49. ±.. ± ±. 9. ±.46.6 ±.6 4. ±.9 (4.+.9) (.8+.7) (.5+.7) (.5+.7) (4.6+5.) (4.+4.8) (.5+.) (.6+.5).5. ±.6. ±.5.7 ±..9 ±. 5.9 ± ±.7.8 ±.. ±.5 7. ± ±.. ±..5 ±.7 (.9+.) (.7+.5) (.9+.9) (.+.) (.+4.) (.+.) (.+.) (.+.5) Dt ±S.E. (n = 5), ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,,, n ) inite signifintly ifferent vlues (DMRT, p<.5) Tle - : Dry weight, 7 n 5 ol Brssi june seeling the presene of mium Conentrtion B. june vrieties (mm) ol seelings (mg fw + S.E.) 7 ol seelings (mg fw + S.E.) 5 ol seelings (mg fw + S.E.) T-59 TM-4 RH- TM- T-59 TM-4 RH- TM- T-59 TM-4 RH- TM-..5 ±..54 ±..8 ±.5.44 ±..5 ±.59.8 ±.9.4 ±.6.6 ±..56 ±.4.4 ±.9.6 ±.5.89 ±. () () () () () () () () () () () ().5.4 ±.4.4 ±..4 ±.. ±..89 ±.6.46 ±.6.9 ±.6. ±.8. ±..79 ±..9 ±.6.47 ±.6..5 ±.4.4 ±..6 ±.. ±.. ±.. ±..86 ±.7.9 ±.6.86 ±.7.6 ±.7.7 ±.9.9 ± ±..6 ±..7 ±.4.9 ±.4. ±.8.9 ±.5.9 ±..4 ±.8.5 ±.6.9 ±..7 ±..74 ±. Dt ±S.E. (n = 5), ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,,, n ) inite signifintly ifferent vlues (DMRT, p<.5) Journl of Environmentl Biology Septemer,

5 Response of Brssi june uner C stress 777 Solue protein (mg g - f.wt.) Solue protein (mg g - f.wt.) Solue protein (mg g - f.wt.) Leves (C) Leves SOD (µmol H O g - f.wt. min - ) SOD (µmol H O g - f.wt. min - ) SOD (µmol H O g - f.wt. min - ) Leves (C) Leves Fig. : Totl solule protein ontent of the vrious plnt prts of Brssi june seelings t, 7 n 5 (C) upon exposure to ifferent mium onentrtions. Vlues re men ± SD (n=). ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,, n ) inite signifintly ifferent vlues (DMRT, p<.5) Tle - 4: Level of Cmium in Brssi june L v. TM-4 n T-59 whole seeling in l onitions when supplie with ifferent onentrtes Conentrtion (mm) 5 ol seelings (µg C g - w) T-59 TM ±. 8. ± ± 44 ±. 684 ±6 67 ±5.5 9 ±79 7 ±9 Dt represent the men ±S.E. (n = 9), ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,, n ) inite signifintly ifferent vlues (DMRT, p<.5) Fig. 4: Speifi peroxise (SPOD) tivity of the vrious plnt prts of Brssi june seelings t, 7 n 5(C) upon exposure to ifferent mium onentrtions. Vlues re men ± SD (n=). ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,, n ) inite signifintly ifferent vlues (DMRT, p<.5) more tolernt/resistnt to C toxiity thn RH- n TM-. Therefore, further nlyses for C umultion n iohemil responses were performe using these two vrieties. Effet of mium exposure on nitrte reutse (NR) tivity, totl orgni nitrogen n solule protein ontent of Brssi june: The NR tivity ws erese upon C exposure t ll urtions in roots n leves of oth vrieties exept in leves of TM-4 fter 7 (Fig. ). In seelings, NR tivity ws reue more rstilly in T-59 (6%) thn in TM-4 (%) t.5 mm C. After 7 n 5, eline in NR tivity in roots of TM- 4 (-55%) ws higher thn tht in roots of T-59 (-6%); while Journl of Environmentl Biology Septemer,

6 778 in leves, the eline ws higher in T-59 (5-44%) thn in TM- 4 (8-9%) (Fig. ). However, the level of totl orgni nitrogen generlly, with few exeptions, inrese signifintly in ll plnt prts viz., roots, stem n leves of oth vrieties t ll urtions s funtion of C onentrtion (Fig. ). The inrese in totl orgni nitrogen ws highly signifint fter (64% in TM-4 n 46% in T-59 t.5 mm C) tht erese with inrese in urtion (7-6% in TM-4 n 7-9% in T-59 t.5 mm C in vrious plnt prts fter 7 n 5 ). Further, the inrese in totl orgni nitrogen ws higher in T-59 thn in TM-4 t ll urtions n in ll plnt prts ut leves. Totl solule proteins in generl showe signifint/ non-signifint erese t ll urtions n onentrtions in omprison to ontrol (Fig. ). After, the eline ws not signifint t ny onentrtion in oth TM-4 n T-59. After 7 n 5, proteins showe signifint eline t.5 mm C in ll the plnt prts in oth vrieties while t. n.5 mm C, protein levels were gin reovere to some extent n even pprohe ontrol levels in some ses. The mximum eline in protein levels fter n 7 ws oserve t.5 mm C. After 5, the mximum eline ws notie t.5 mm C in roots (47% in TM-4 n 7% in T-59) n stems (4% in TM-4 n % in T-59), however in leves the mximum eline in protein levels of TM-4 (6%) ws oserve t.5 mm C while in T-59 (4%) t.5 mm C. Nitrte reutse is onsiere s key enzyme n rte limiting step in the nitrogen metolism of the plnts (Bhrti n Singh, 994; Bhrti et l., 996; Singh et l., 997). The enzyme tlyzes reution of nitrte to nitrite n its tivity is often orrelte with the nitrogen sttus of the plnt. Vrile effets of hevy metls espeilly P n C on NR tivity hve een reporte (Singh et l., 997; Hyt et l., 7). The reson for the inhiition of NR tivity in response to C exposure might e multi-fil. It might e ue to (i) reue supply of NADH, whih my either e oxiize ue to the presene of metl t the site or its genertion my e inhiite ue to the moifition of struture n funtion of ellulr omponents, (ii) reue uptke of nitrte or wter stress rete in the plnts ue to C toxiity (Singh et l., 997) n (iii) iret effet of the C ue to its strong ffinity with the funtionl -SH group of the enzyme (Chouhry n Singh, ). Totl solule proteins of the plnts were inhiite upon C exposure wheres totl orgni nitrogen ws generlly inrese s funtion of the stress. The mium pplie to the seelings my inrese the trnslotion of reserve N from the otyleons to the growing roots n shoots in the erly growth phse s it hs een orrelte with erese orgni N ontent in the otyleons in Sesmum inium uner P + environment (Kumr et l., 99). It seems tht reue tivity of NR n use of signifint mount of nitrogen for the synthesis of PCs, MTs n other stress responsive proteins proly resulte in erese in the levels of totl solule proteins ut the C inuile proteins. We oserve n inution of some stress proteins upon C exposure s revele y SDS-PAGE protein profiling of the two vrieties, whih inites towrs n inution of stress responsive ntioxint enzymes or e novo synthesis of stress proteins (Blin et l., 997). In mung en Chouhry n Singh, Shrm et l. () hs reporte synthesis of oth low n high moleulr weight proteins in the presene of C n P ut no speifi funtion for these inue proteins oul e ssigne. Effet of mium exposure on the peroxise tivity n proline ontent in Brssi june: Speifi peroxise tivity inrese to highly signifint levels upon C exposure t ll C onentrtions n urtions in vrious plnt prts of oth vrieties (Fig. 4). The inrese in peroxise tivity ws higher in T-59 thn in TM-4 in ll plnt prts n uner vrious onitions exept in stem of TM-4 fter 5. The mximum inreses in peroxise tivity in root, stem n leves fter 5 were, 586 n 95%, respetively in TM-4 n 5, 4 n 57%, respetively in T-59. Similr to peroxise, the proline ontent in root, stem n leves of the two vrieties ws lso inrese signifintly y mnyfol t ll urtions n onentrtions (Fig. 5). By ontrst to peroxise, the inrese in proline levels ws lwys higher in TM-4 thn in T-59. The mximum inreses in proline ontent in root, stem n leves fter 5 were 65, 75 n %, respetively in TM-4 n 5, 86 n 44%, respetively in T- 59. Signifint inrese oserve in the levels of peroxise n proline ppers to e n ptive response of the plnts to omt C toxiity. Peroxises re lote in ytosol, ell wll, vuole n extrellulr spes. This is onsiere s stress mrker enzyme hving ro speifiity for phenoli sustrtes n higher ffinity for H O thn tlse (Rey et l., 5). Proline hs een suggeste to ply n importnt role in osmoregultion, protetion of enzymes, stiliztion of the mhinery of protein synthesis, regultion of ytosoli iity, s well s in nonenzymti free ril etoxifition (Ali n Srhi, 99; Ali et l., 995). Signifint inrese oserve in the peroxise tivity n proline levels ppers to e orrelte to C stress suggesting it to e n intrinsi efense tool (Mishr et l., 6; 8). Signifint inrese in peroxise tivity n/or proline levels in Brssi june plnts upon exposure to C hs een reporte previously (Dhir et l., 4; Hyt et l., 7). An inrese in peroxise tivity upon C exposure hs lso een oserve in other terrestril plnts, suh s Lyopersion esulentum n Tritium estivum (Dong et l., 6; Lin et l., 7). Cmium umultion: The level of C umulte y the plnts ws nlyze fter 5 of seeling growth t whole plnt level. Plnts showe progressive inrese in C umultion with n inrese in C onentrtion (Tle 4). The mximum level of C ws oserve t.5 mm C tht ws higher in T-59 (9 mg g - w) thn in TM-4 (7 mg g - w). Differentil C umultion of C y vrious ultivrs of Brssi june (Qir et l., 4) or ifferent speies of Brssi viz., B. june n B. npus hs een reporte previously (Nouiri et l., 6). The level of C umultion oserve in this stuy ws foun to e higher thn tht reporte previously (Qir et l., 4). In B. june, it hs een emonstrte tht C umultes preferentilly Journl of Environmentl Biology Septemer,

7 Response of Brssi june uner C stress 779 Proline (µmol g - f.wt.) Proline (µmol g - f.wt.) Proline (µmol g - f.wt.) (C) Leves Leves Fig. 5: Proline level of the vrious plnt prts of Brssi june seelings t, 7 n 5 (C) upon exposure to ifferent mium onentrtions. Vlues re men ± SD (n=). ANOVA signifint t p<.. For prtiulr vriety, ifferent letters (,,, n ) inite signifintly ifferent vlues (DMRT, p<.5) in the trihomes of the youngest lef surfe (Slt et l., 995). The storge of C in trihomes my represent etoxifition mehnism, sine trihomes represent n externl tissue to the lef. The high C umultion potentil of B. june might e ttriute to its potentil to helte it through metl ining ligns, phytoheltins (Slt et l., 995; Mishr et l., 6) n low moleulr weight proteins, MTs (Shäfer et l., 997) in ition to its pity to tolerte C inue oxitive stress through inue ntioxint systems (Qir et l., 4; Hyt et l., 7). Of the four vrieties sreene for tolerne to C toxiity, RH- n TM- were foun more sensitive thn TM-4 n T-59 s evlute in terms of seeling growth. Vriety T-59 ws foun to possess the gretest tolerne mong the four teste ultivrs. In ition, T-59 showe higher umultion of C thn tht oserve in TM-4. Hene, the B. june ultivr T-59 ppers to possess greter tolerne to C toxiity n thus seems suitle nite for phytoremeition of C. There is nee of further stuies t fiel level to utilize the potentil of suitle vrieties for the purpose of phytoremeition in oming future. Aknowlegments SD is grteful to Deprtment of Siene n Tehnology, New Delhi, Ini for the wr of Young Sientist fellowship. Referenes Ahme, K.S., B.S. Pnwr n S.P. Gupt: Phytoremeition of miumontminte soil y Brssi speies. At Agronomi Hungri, 49, 5-6 (). Ain, R., M. Lr, P. Fumglli, C. Vmnini, M. Mrsoni, U. Cuhi, M. Brle, S. Sgorti n S. Citterio: Thiol peptie level n proteomi hnges in response to mium toxiity in Oryz stiv L. roots. Environ. Exp. Bot., 59, 8-9 (7). Ali n Srhi, P.P.: Proline umultion uner hevy metl stress. J. Plnt Physiol., 8, (99). Ali Prs, K.V.S.K. n P. Prh Srhi: Effet of zin on free ril n proline in Brssi june n Cjnus jn. Phytohem., 9, (995). Brelo, J. n C. Poshenrieer: Plnt wter reltions s ffete y hevy metl stress: A review. Plnt Nutrition,, -7 (99). Btes, L.S., R.P. Wleen n I.D. Tere: Rpi etermintion of free proline for wter stress stuies. Plnt Soil, 9, 5-7 (97). Bhrti, N., n R.P. Singh: Antgonisti effet of NCl to ifferent hevy metl toxiity regring in vivo nitrte reutse tivity n orgni nitrogen ontents of roots n leves of Sesmum inium L. Cv. PB-. Phytohemistry, 5, 57-6 (994). Bhrti, N., R.P. Singh n S.K. Sinh: Effet of CCl on hevy metl inue ltertion in growth n nitrte ssimiltion of Sesmum inium seelings. Phytohemistry, 4, 5-9 (996). Blin, A., B. Koh, S. Rmnjulu n K.J. Dietz: De Novo synthesis n umultion of poplsti proteins in leves of hevy metl-expose rley seelings. Plnt Cell Environ.,, (997). Brfor, N.M.: A rpi n sensitive metho for quntition of mirogrm quntities of protein utilizing the priniple of protein ye ining. Anlytil Biohem., 7, 48-54(976). Chney, R.L.: Metl speition n intertions mong elements ffet tre element trnsfer in griulturl n environmentl foo-hins In: Metl speilion-theory, nlysis n pplition (Es.: J.R. Krmer n H.E. Allen). Lewis Pulishers. pp. 9-6 (998). Chouhry, A. n R.P. Singh: Cmium-inue hnges in imine oxise tivity n polymine levels in Vign rite Wilzek seelings. J. Plnt Physiol., 56, 74-7 (). Chuhry, Shikh n Yogesh Kumr Shrm: Intertive stuies of potssium n opper with mium on see germintion n erly seeling growth in mize (Ze mys L.). J. Environ. Biol.,, 47-4 (9). Dhir, B., P. Shrmil n P.P. Srhi: Hyrophytes lk potentil to exhiit mium stress inue enhnement in lipi peroxition n umultion of proline. Aquti Toxiol., 66, 4-47(4). Di Toppi, L.S. n R. Grielli: Response to mium in higher plnts. Environ. Exp. Bot., 4, 5- (999). Dinkr, N., P.C. Ngjyothi, S. Suresh, T. Dmohrm n C. Suresh: Cmium inue hnges on proline, ntioxint enzymes, nitrte n nitrite reutses in Arhis hypoge L. J. Envrion. Biol.,, (9). Journl of Environmentl Biology Septemer,

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