低剂量微波辐射对增强UV_B辐射损伤菘蓝幼苗抗氧化酶活性的影响_英文_

西北植物学报Κ2005Κ25; 11ΓΠ2219—2225 A cta B ot. B orea l. -O cciden t. S in. 文章编号Π100024025; 2005Γ1122219207 低剂量微波辐射对增强 UV-B 辐射损伤菘蓝 幼苗抗氧化酶活性的影响α 陈怡平1Κ2Κ刘永军3Κ赵萌萌4Κ崔　瑛2; 1 中国科学院地球环境研究所Κ西安 710075Μ2 西安工程科技学院 生物工程系Κ西安 710048Μ3 西安建筑科技大学 环境学院Κ西 安 710054Μ4 西北大学 生命科学学院Κ西安 710069Γ 摘　要Π为了探讨低剂量微波对增强UV 2B 辐射损伤菘蓝; Isa tis ind ig otica Fo rt. Γ的修复作用Κ将经过 10. 08 kJ· m - 2·d- 1辐射损伤; PA R = 220 Λmo l·m - 2·s- 1Γ的菘蓝幼苗分别经 0、3、6、9 和 12 s 等不同时间的微波辐照; 126 mW ·cm - 2Κ2 450 M H zΓΚ然后测定其幼苗M DA 含量、紫外吸收物质含量、抗坏血酸含量以及 3 种抗氧化酶 SOD、 CA T 和 POD 活性Λ结果明Κ增强UV 2B 辐射损伤菘蓝在微波的作用下其菘蓝幼苗中 SOD、CA T 和 POD 活性及 紫外吸收物质含量、抗坏血酸含量提高ΚM DA 含量得到显著的降低Κ说明微波对增强UV 2B 辐射伤害菘蓝幼苗具 有修复作用Λ但是Κ随着微波剂量的增加Κ这种修复效应减弱Κ甚至消失Λ上述参数的变化说明适量时间的微波处理 可以提高菘蓝对增强UV 2B 辐射的抵抗能力Κ并在此基础上初步探讨了微波的修复机理Λ 关键词Π菘蓝Μ微波ΜUV 2B 辐射Μ修复效应 中图分类号ΠQ 947. 9　　　文献标识码ΠA Inf luence of L ow D osesM icrowave Rad ia tion on Activ it ies of An tiox ida tive Enzym es of Isa tis ind igotica Seedl ings Exposed to Enhanced UV-B Rad ia tion CH EN Y i2p ing1Κ2ΚL IU Yong2jun3ΚZHAO M eng2m eng4ΚCU I Y ing2; 1 Institu te of Earth Environm entΚCh inese A cadem y of SciencesΚX ipian 710075ΚCh inaΜ2 D epartm en t of B ioengineeringΚX ipian U ni2 versity of Engineering Science and T echno logyΚX ipian 710048ΚCh inaΜ3 Co llege of Environm ent ScienceΚX ipian U niversity of A rch i2 tectu re and T echno logyΚX ipian 710054ΚCh inaΜ4 Co llege of L ife ScienceΚN o rthw est U niversityΚX ipian 710069ΚCh inaΓ AbstractΠIn o rder to determ ine the dam age repair ro le of m icrow ave in the st ress resistance of Isa tis ind ig 2 otica to UV 2B radia t ionΚthe seedlings sub jected to UV 2B radia t ion of 10. 08 kJ·m - 2·d- 1 fo r 8 h under pho to syn thet ica lly act ive radia t ion ; 220 Λmo l·m - 2·s- 1Γw ere expo sed to m icrow ave radia t ion of 0Κ3Κ6Κ9 and 12 s ; 126 mW ·cm - 2Κ2 450M H zΓ. A fterw ardsΚchanges of UV 2B 2in ju red leaves of the fou rth in the ac2 t ivit ies of enzym esΚsuch as SOD ΚCA T and POD Κand in the concen tra t ion of m alondia ldehyde ;M DA Γ and asco rb ic acid ;A sA ΓΚand UV ab so rb ing compounds w ere m easu red to test the effects of m icrow ave trea t2 m en t. T he resu lts ind ica ted w hen the seedlings w ere trea ted u sing 10. 08 kJ·m - 2·d - 1 UV 2B and then ex2 po sed to sho rter m icrow ave radia t ionΚthe act ivit ies of SOD ΚCA T and POD Κand the concen tra t ion of A sA Κ and UV ab so rb ing compounds increased sign if ican t ly. UV 2B 2in ju red Isa tis ind ig otica seedlings trea ted w ith m icrow ave radia t ion recovered faster from enhanced UV 2B stress resistance becau se the M DA concen tra2α 　收稿日期Π2005203225Μ修改稿收到日期Π2005209223 基金项目Π中国博士后科学基金资助; 2005037245ΓΜ国家自然科学基金资助; 30370269Γ 作者简介Π陈怡平; 1968- ΓΚ男;汉ΓΚ教授Κ博士Κ主要从事环境植物学的研究Λ t ion decreased compared w ith UV 2B treatm en t a lone. How everΚthe repaired effect on seedlings in ju red by UV 2B dam age becam e w eakΚand even lo st w ith the augm en t of m icrow ave radia t ion t im e. T ho se changes in the vigo r of enzym es and in concen tra t ion ofM DA ΚA sA and UV 2B ab so rb ing compound suggested that m i2 crow ave radia t ion of su itab le t im e length had a po sit ive physio logica l repair ro le on UV 2B 2dam aged p lan ts. How everΚthe m echan ism s of m icrow ave repair effect in p lan ts dam aged by UV 2B are no t clear a t p resen t and addit ional w o rk w ill be needed to invest iga te in the fu tu re. Key wordsΠIsa tis ind ig oticaΜm icrow aveΜUV 2B lesionΜrepair ro le 　　U ltravio let2B radia t ion levels are st ill rela t ive2 ly h igh at the earthpis su rface due to the dep let ion of st ra to spheric ozone by the ch lo rofluo rocarbon s re2 leased in to the atmo sphere since the m id2n ine2 teen th cen tu ry. Cu rren t UV 2B levels are expected to increase in the even t of M on trea l P ro toco l no t being fu lly imp lem en ted by the m em ber coun2 t ries[1 ]. UV 2B direct ly dam ages p lan tspi cellu lar m em b ranes and free radica l elim inat ion system s such as severa l an t iox idat ive enzym es including su2 perox ide dism u tase ; SOD ΓΚcata lase ;CA T ΓΚperox2 idase ; POD Γ and so on. T herefo reΚUV 2B 2induced reduct ion s in p lan t grow th o r p roduct ivity are linked to altered leaf physio logy and funct ion [2 ]. E l2 evated UV 2B radia t ion can be con sidered a sign if i2 can t po ten t ia l environm en ta l st ress in natu ra l e2 co system s and agricu ltu re. P reviou s research has il2 lu st ra ted that h igh pho to syn thet ica lly act ive radia2 t ion ; PA R Γ[3 ]Κh igh concen tra t ion of CO 2 [4 ]Κand low n it rogen supp ly [5 ] can each allevia te cell dam 2 age induced by UV 2B irrad ia t ion. R ecen t lyΚQ iΚet a l. [6 ] also repo rted that laser can also allevia te cell dam age of V icia f aba L. ;L egum ino seaΓ induced by UV 2B irrad ia t ion. N um erou s studies have demon stra ted that m i2 crow ave radia t ion has a po sit ive ro le of accelera t ing p lan ts seeds germ inat ion [7 ]Κ imp roved o il quality and increased yield of grape seed [8 ]Κand imp rove m ale and fem ale flow er fo rm at ion of cucum ber [9 ]. To ou r know ledgeΚhow everΚlit t le is know n abou t the dam age repair ro le of m icrow ave trea tm en t in Isa tis ind ig otica expo sed to enhanced UV 2B radia2 t ion. In the p resen t studyΚw e have exam ined the an t iox idat ive enzym es act ivit iesΚthe concen tra t ion of A sA ΚUV ab so rb ing compounds and M DA con2 cen tra t ion to test the hypo thesis tha t w hether the m icrow ave has the repair effect on the seedlings in2 ju red by enhanced UV 2B radia t ion. 1　M ateria ls and m ethods 1. 1　Plan t ma ter ia ls Co llege of Pharm acy of X ipian J iao tong U n iver2 sity supp lied seeds of Isa tis ind ig otica as m ateria ls. 1. 2　M ethods 1. 2. 1　Seeds germ ina tion 　U n ifo rm and p lump seeds w ere selected fo r experim en tΚthey w ere ster2 ilized fo r 10 m in by 0. 05% H gC l2 and w ashed fo r 30 m in by flow ing w ater. T hey w ere grow n in p las2 t ic po ts ; 30 cm ×35 cm ΓΚf lu shed daily w ith a 10 mL half2st rength so lu t ion cu ltu re m edium of M S. Every experim en t is comp rised of 18 p last ic po tsΚ each p last ic po t con ta ined 20. T he po ts w ith seeds w ere incubated in grow th cham ber w ith hum idity;M odelΠ515HD ΚU SA Γ at 25℃Κ70% rela t ive hu2 m idityΚand 400 Λmo l·mo l- 1 CO 2; am b ien t level in the bu ild ing Γ. W hen the seedlings w ere 10 d o ld under ligh t condit ion s of a PA R of 220 Λmo l·m - 2 · s- 1Κthey w ere divided in to 6 group sΚ3 po ts per group. O ne w as u sed as the con tro l ;w ithou t UV 2B and m icrow ave radia t ionΚCK ΓΚo thers as fo llow Π UV 2B radia t ion alone ; B ΓΚUV 2B radia t ion fo l2 low ed by 3 s m icrow ave radia t ion ;B 3sΓΚUV 2B ra2 dia t ion fo llow ed by 6 s m icrow ave radia t ion ;B 6sΓΚ UV 2B radia t ion fo llow ed by 9 s m icrow ave radia2 t ion ;B 9sΓΚUV 2B radia t ion fo llow ed by 12 s m i2 crow ave radia t ion ;B 12sΓ. 1. 2. 2　UV-B trea tm en t　UV 2B radia t ion w as p ro2 vided by filtered Q in b rand ;Bao ji L amp Facto ryΚ Ch inaΓ 30 W fluo rescence sun lamp s fo llow ing the p rocedu re ou t lined by FengΚet a l. [10 ]. T he lamp s w ere su spended above and perpendicu lar to the p last ic po t and filtered w ith either 0. 13 mm th ick 0222 西　北　植　物　学　报 25 卷 cellu lo se diaceta te ; t ran sm ission dow n to 290 nm Γ fo r UV 2B irrad iance o r 0. 13 mm po lyester p last ic f ilm s ; ab so rb ing all rad ia t ion bellow 320 nm Γ as a con tro l. Cellu lo se diaceta te f ilters w ere p reso lar2 ized. T he desired irrad ia t ion w as ob ta ined by changing the distance betw een the lamp s and the p last ic po t. T he spectra l irrad iance from the lamp s w as determ ined w ith an Op tron icsM odel 742 ;Op2 t ron ics L ab sΚ O rlandoΚ FL Κ U SA Γ spectro ra2 diom eter. T he spectra l irrad iance w as w eigh ted u s2 ing a genera lized p lan t respon se act ion spec2 t rum [11Κ12 ] ; Caldw ellΚ1971Γ and no rm alized at 300 nm to ob ta in the desired level of b io logica lly effec2 t ive UV 2B radia t ion ;UV 2BBE Γ. T he do se of UV 2B irrad ia t ion w as 10. 08 kJ·m - 2. In addit ion to UV 2 B radia t ionΚthe visib le rad ia t ion ; PA R 400～ 700 nm Γ ; 220 Λmo l·m - 2·s- 1Γw as also supp lied. 1. 2. 3　M icrowave trea tm en t　M icrow ave ;pow er den sity 126 mW ·cm - 2Κ2 450 M H zΓ direct ly irra2 dia ted the seedlings of Isa tis ind ig otica fo r 3Κ6Κ9 and 12 sΚrespect ively. Every po t w as trea ted on ly once under m icrow ave irrad ia t ion. T he m icrow ave oven ; Com b i2Grill m icrow ave oven W D 700Γ w as m ade by Shunde m icrow ave in st itu te. 1. 2. 4　D eterm ina tion s　M alondia ldehyde ;M DA Γ concen tra t ion w as m easu red acco rd ing to P redieriΚ et a l [12 ]. Samp le of the fou rth leaves ; 0. 2 g fresh w eigh tΚFW Γ w ere taken from Isa tis ind ig otica seedlings of 25 d and imm edia tely frozen at - 70℃ and m ateria ls w ere homogen ized in 5 mL pho sphate buffer ;pH 6. 7ΓΚand then cen trifuged fo r 15 m in at 8 000 g. A 0. 5 mL supernatan t w as com b ined w ith an equal vo lum e of th iobarb itu ric acid ; TBA Γ reagen t [ 5% TBA ;W öV Γ in 20% trich lo roacet ic acid ;W öV Γ] and bo iled at 100℃ fo r 20 m in. A b2 so rbance w as determ ined at 532 and 600 nm. M DA concen tra t ion w as exp ressed as nmo l·m g- 1 p ro2 tein. Concen tra t ion of A sA w as m easu red acco rd ing to Tonam u ra [13 ]. Samp les of the fou rth leave of 25 d seedlings ; 0. 2 g FW Γw ere taken and p laced in a mo rtar fo llow ing the addit ion of silicaΚN aC l and 10% m etapho spho ric acid. A fter tho rough grind2 ingΚthe samp le w as cen trifuged fo r 3 m in at 6 500 g. A supernatan t samp le w as taken and fixed to 25 mL Κand then a 0. 5 mL removed from the 25 mL Κ and in p roper o rderΚ1 mL of cit ric acid2pho spho ric acid buffer ;pH 2. 3Γand 1 mL of 2Κ62dich lo rophe2 no l indopheno l ; 30 m g·L - 1 Γ added. A fter 30 sΚ the velocity of ab so rbance w as determ ined at 524 nm. A sA concen tra t ion w as exp ressed as Λg·g - 1 FW. F resh samp le of 0. 5 g w ere taken from the fou rth leaves and ex tracted in 10 mL acid if ied m ethano l ;m ethano l2w ater2hydroch lo ric acidΚ7∶20 ∶1ΚV öV Γ fo r UV 2B ab so rb ing compounds acco rd2 ing to the p rocedu re of M ireck i and T eram u ra [14 ]. T he hydroch lo ric acid w as 36% HC l. Ex tract ab2 so rbance w as m easu red w ith a spectropho tom eter; UV 22100ΜSh im adzuΚCo lum b iaΚM D ΚU SA Γ and the ab so rbance w as arb it rarily u sed fo r analysis. Ex tract ion of enzym es w as carried ou t a t 4℃. 5 g fresh t issues of the fou rth leaves of 25 d seedlings homogen ized in 10 mL 0. 05 mo l·L - 1 pho sphate buffer ; pH 6. 7ΓΚafter tho rough grind2 ingΚthe samp le at 0℃ w as cen trifuged fo r 10 m in at 10 000 g. T he supernatan t samp le w as sto red at - 20 ℃ fo r assay. A ct ivit ies of SOD ΚPOD and CA T w ere determ ined acco rd ing to Giannopo lit is and R eies[15 ]ΚN akano and A sada [16 ] and Cakm akΚet a l. [17 ]Κrespect ively. T he act ivity of enzym es w as exp ressed as U ·m g- 1 p ro tein. 1. 2. 5 　 Sta tist ica l ana lysis 　 Samp les w ere ar2 ranged in comp letely random ized design s w ith 6 in2 dependen t experim en ts w ith 6 rep lica t ion s. A ll the values are tested 6 t im es ; n= 6Γ. Sign if ican t d iffer2 ence ; P < 0. 05 Γ w as determ ined acco rd ing to D uncanpis m u lt ip le range tests. 2　R esu lts Compare w ith the con tro l ;CKΓΚUV 2B radia2 t ion alone cau se a sign if ican t increase of 2. 03 nmo l ·m g- 1 p ro tein ; P < 0. 05Γin the concen tra t ion of M DA ; F ig. 1Γ. In con trastΚw hen UV 2B irrad ia t ion fo llow ed m icrow ave radia t ionΚM DA concen tra t ion w as decreased in som e degree. Fo r examp leΚcom 2 pare w ith UV 2B radia t ion alone ;B ΓΚM DA concen2 122211 期 陈怡平Κ等Π低剂量微波辐射对增强UV 2B 辐射损伤菘蓝幼苗抗氧化酶活性的影响;英Γ t ra t ion of UV 2B irrad ia t ion fo llow ed 6 s m icrow ave radia t ion w as the least among fou r t rea tm en tsΚit w as 1. 93 nmo l·m g - 1 p ro tein; P < 0. 05Γ less than that of B group ΜUV 2B irrad ia t ion fo llow ed 3Κ9 and 12 s m icrow ave radia t ionΚ the concen tra t ion of M DA w as 1. 53 nmo l·m g- 1 p ro tein ; P < 0. 05ΓΚ 1. 70 nmo l·m g- 1 p ro tein ; P < 0. 05ΓΚ0. 13 nmo l· m g - 1 p ro tein ; P < 0. 05Γ less than that of B group Κ respect ively. F ig. 1　M DA conten ts of the seedlings in ju red by en2 hanced UV 2B radiat ion in treatm ents of m icrow ave ra2 diat ion T here are six treatm en tsΠ; 1Γ the con tro l ; CK ΓΜ; 2Γ UV 2B treatm en t;BΓΜ; 3ΓUV 2B treatm en t fo llow ed by 3 s m icrow ave treatm en t ; B3sΓΜ; 4 ΓUV 2B treatm en t fo llow ed by 6 s m i2 crow ave treatm en t;B6sΓΜ; 5ΓUV 2B treatm en t fo llow ed by 9 s m icrow ave treatm en t;B9sΓΜ; 6ΓUV 2B treatm en t fo llow ed by 12 s m icrow ave treatm en t ;B12sΓ ; T he no tes are the sam e as below Γ F ig. 2　A sA conten ts of the seedlings in ju red by enhanced UV 2B radiat ion in the treatm ents of m icrow ave radia2 t ion F ig. 3　A bso rbance at 300 nm of the seedlings in ju red by enhanced UV 2B radiat ion Sim ilarlyΚF ig. 2 show n that UV 2B radia t ion alone cau se a sign if ican t decrease of 31. 3 Λg·g - 1 FW ; P < 0. 05Γ in the concen tra t ion of A sA com 2 pare w ith the con tro l ;CKΓ. In con trastΚw hen UV 2 B irrad ia t ion fo llow ed m icrow ave radia t ionΚconcen2 t ra t ion of A sA w as differen t degree increased. Fo r examp leΚUV 2B irrad ia t ion fo llow ed 3Κ6Κ9 and 12 s m icrow ave radia t ionΚand the concen tra t ion of A sA w as increase of 28. 8 Λg·g- 1 FW ; P < 0. 05ΓΚ57. 6Λg·g- 1 FW ; P < 0. 05ΓΚ23. 6 Λg·g - 1 FW ; P < 0. 05ΓΚ12. 2 Λg·g- 1 FW ; P < 0. 05Γcompared w ith UV 2B treatm en t a loneΚrespect ively. F ig. 4　SOD activit ies of the seedlings in ju red by en2 hanced UV 2B radiat ion in the treatm ents of m icrow ave radiat ion Compare w ith the con tro l ;CKΓΚUV 2B radia2 t ion alone cau se a sign if ican t increase of 0. 027% ; P < 0. 05Γin the concen tra t ion of UV 2B ab so rb ing compounds ; F ig. 3Γ. W hen UV 2B irrad ia t ion fo l2 2222 西　北　植　物　学　报 25 卷 low ed m icrow ave radia t ionΚab so rb ing compounds w as increased drast ica lly. Fo r examp leΚcompare w ith B group ;B ΓΚUV 2B irrad ia t ion fo llow ed 3Κ6Κ9 and 12 s m icrow ave radia t ionΚand concen tra t ion of UV 2B ab so rb ing compounds w as 0. 158% ; P < 0. 05ΓΚ0. 312% ; P < 0. 01ΓΚ0. 24% ; P < 0. 05ΓΚ0. 19%; P < 0. 05Γmo re than that of B group Κrespect ively. F ig. 5　CA T activit ies of the seedlings in ju red by en2 hanced UV 2B radiat ion in the treatm ents of m icrow ave radiat ion A ctivit ies of SOD and CA T w ere declined rap id ly by UV 2B radia t ion compared w ith con tro l; F ig. 4 and F ig. 5ΓΚw h ich w ere 1. 5 U ·m g- 1 p ro2 tein ; P < 0. 05ΓΚ4. 79 U ·m g- 1 p ro tein; P < 0. 05ΓΚ low er than that of CKΚrespect ively. O n the con2 t raryΚw hen UV 2B treated seedlings w ere expo sed to 3 s m icrow ave radia t ionΚact ivit ies of SOD and CA T w ere 1. 1 U ·m g- 1 p ro tein ; P < 0. 05ΓΚ16. 09 U ·m g - 1 p ro tein ; P < 0. 05Γ h igher than that of UV 2B radia t ion aloneΜexpo sed to 6 s m icrow ave ra2 dia t ionΚact ivit ies of SOD and CA T w ere 1. 76 U ·m g- 1 p ro tein ; P < 0. 05ΓΚ17. 54 U ·m g- 1 p ro2 tein ; P < 0. 01Γh igher than that of UV 2B radia t ion aloneΜ9 s m icrow ave radia t ion of UV 2B 2induced seedlings cau se a sign if ican t imp rovem en t of 1. 95 U ·m g- 1 p ro tein; P < 0. 05ΓΚ9. 23 U ·m g - 1 p ro tein; P < 0. 05Γin the act ivit ies of SOD and CA T com 2 pare w ith B group Μ12 s m icrow ave radia t ion of UV 2B 2induced seedlings w ere on ly cau se a sign if i2 can t imp rovem en t of 1. 68 U ·m g- 1 p ro tein ; P < 0. 05ΓΚ8. 04 U ·m g- 1 p ro tein ; P > 0. 05Γin the ac2 t ivit ies of SOD and CA T respect ively. A ct ivit ies of POD w ere declined rap id ly by UV 2B radia t ion compared w ith con tro l ; F ig. 6 ΓΚ w h ich 4. 17 U ·m g- 1 p ro tein; P < 0. 05Γlow er than that of CK. O n the con traryΚw hen UV 2B treated seedlings w ere expo sed to 3 s m icrow ave radia t ionΚ act ivit ies of POD w as 3. 89 U ·g - 1 p ro tein ; P < 0. 05Γh igher than that of UV 2B radia t ion aloneΜex2 po sed to 6 s m icrow ave radia t ionΚPOD act ivit ies w as 4. 83 U ·m g- 1 p ro tein ; P < 0. 01Γh igher than that of UV 2B radia t ion aloneΜ9 s m icrow ave radia2 t ion of UV 2B 2induced seedlings cau se a sign if ican t imp rovem en t of 2. 21 U ·m g- 1 p ro tein ; P > 0. 05Γ in the act ivit ies of POD compare w ith B group Μ12 s m icrow ave radia t ion of UV 2B 2induced seedlings w as on ly cau se a sign if ican t imp rovem en t of 1. 11 U ·m g- 1 p ro tein; P < 0. 05Γin the POD act ivit ies. F ig. 6　POD activit ies of the seedlings in ju red by en2 hanced UV 2B radiat ion in treatm ents of m icrow ave ra2 diat ion 3　D iscu ssion T he resu lts from m uch of the rela ted research indica te that enhanced UV 2B radia t ion can adverse2 ly influence the physio logica l and b iochem ical p ro2 cess of p lan ts[4 ]. P reviou s studies have demon stra t2 ed that po ten t ia l key target fo r UV 2B dam age is m em b ranesΚDNA and o thers m icromo lecu lar [18 ]. W hen p lan ts w ere expo sed to elevated UV 2B irra2 dia t ion sΚthe b iom em b rane is in ju red and allow s ion s such as K+ ΚN a+ inf ilt ra te [19 ]Κresu lt ing in the decrease of the un satu ra ted fa t ty acids ra t io and the mob ility of the cell m em b rane [18 ]Κlead to p ro2 duce free radica ls in p lan ts[20 ]. A s the resu ltΚthe concen tra t ion of M DA Κas an indica to r of lip id per2 322211 期 陈怡平Κ等Π低剂量微波辐射对增强UV 2B 辐射损伤菘蓝幼苗抗氧化酶活性的影响;英Γ ox idat ionΚ is increased and p lan t cells are in2 ju red [21 ]. T herefo reΚhow to decrease the concen tra2 t ion of M DA is very impo rtan t th ing fo r reducing dam age of elevated UV 2B radia t ion p lan ts. T here are a few w ays to reso lve th is p rob lem Κsuch as in2 creasing superox ide dism udase ; SOD ΓΚperox idase; POD Γ and cata lase ;CA T Γ act ivityΚA sA concen2 t ra t ion and UV 2B ab so rb ing compounds in p lan ts. P resen t lyΚsom e study indica ted that laser rad ia t ion also ach ieve th is a im [22 ]. In th is studyΚou r resu lts p resen ted here the concen tra t ion of M DA w ere in2 creased sign if ican t ly w hen seedlings w ere expo sed to enhance UV 2B radia t ionΚw h ich suppo rt the hy2 po thesis tha t cellm em b rane is a key target fo r UV 2 B radia t ion [18 ]. How everΚenhanced UV 2B radia t ion fo llow ed m icrow ave radia t ionΚthe resu lt of a no2 tab le decrease of M DA concen tra t ion w as ob2 served. W en t w ithou t sayingΚthe m icrow ave is ab le to recovery the in ju red cellu lar m em b rane and re2 pair p lan t dam age by UV 2B radia t ion. T he p rob lem is w hat pathw ays w ere u sed by m icrow ave to repair the UV 2B dam age. In ch lo ro2 p lastsΚSOD ΚCA T and POD are regarded as key en2 zym es of the scavenging pathw ayΚand UV 2B radia2 t ion is know n to induce a decrease in their act ivi2 t ies[23 ]. In th is studyΚact ivit ies of SOD ΚCA T and POD in the fou rth leaves of seedlings w ere sign if i2 can t ly decreased by UV 2B radia t ionΚju st as above repo rted. How everΚafter the UV 2B dam age in the seedlings fo llow ed m icrow ave radia t ionΚtho se an2 t iox idat ive enzym es act ivit ies w ere sign if ican t ly in2 creased. M eanw h ileΚthe M DA concen tra t ion s w ere no tab ly decreased w ith the increasing of an t iox ida2 t ive enzym es act ivit ies. It w as w ell know n that tho se an t iox idat ive enzym es cou ld elim inate free rad ica ls and p reven t lip id perox idat ion [23 ]. T here2 fo reΚm icrow ave m ay part icu lar in the repair effect of seedlings in ju red by UV 2B radia t ion th rough im 2 p roving act ivit ies of som e an t iox idat ive enzym es. T he nex t p rob lem is w hether the repair effect of m icrow ave w as associa ted w ith increase ex2 p ressed of an t itox ican t genes. In recen t yearsΚsom e studies abou t hT ER T 2R PE1 show n that m i2 crow ave radia t ion can ra ise the exp ress of tox icide genes[24 ]. UV 2B expo sed cou ld increase UV 2B ab2 so rb ing compo