大氣汞濃度升高對(duì)水稻葉片生理效應(yīng)的影響研究

陳劍，王章瑋，張曉山，秦普豐，陸海軍

1.中國(guó)科學(xué)院生態(tài)環(huán)境研究中心大氣環(huán)境科學(xué)實(shí)驗(yàn)室，北京100085

2.中國(guó)科學(xué)院大學(xué)資源與環(huán)境學(xué)院，北京100049

3.湖南農(nóng)業(yè)大學(xué)資源環(huán)境學(xué)院，長(zhǎng)沙410128

大氣汞濃度升高對(duì)水稻葉片生理效應(yīng)的影響研究

陳劍1,2，王章瑋1,*，張曉山1，秦普豐3，陸海軍3

1.中國(guó)科學(xué)院生態(tài)環(huán)境研究中心大氣環(huán)境科學(xué)實(shí)驗(yàn)室，北京100085

2.中國(guó)科學(xué)院大學(xué)資源與環(huán)境學(xué)院，北京100049

3.湖南農(nóng)業(yè)大學(xué)資源環(huán)境學(xué)院，長(zhǎng)沙410128

采用大田開頂式氣室熏氣實(shí)驗(yàn),研究大氣汞濃度升高對(duì)水稻葉片氣體交換參數(shù)、脯氨酸、丙二醛的積累以及超氧化物歧化酶活性的影響。實(shí)驗(yàn)結(jié)果顯示,水稻葉片凈光合速率(Pn)和氣孔導(dǎo)度(Gs)隨大氣汞濃度的升高均較對(duì)照略微下降,表明大氣汞濃度的升高對(duì)水稻光合作用和氣孔開放程度有一定影響；揚(yáng)花期水稻胞間CO2濃度(Ci)隨大氣汞濃度的升高明顯降低(P＜0.05)表明Pn的略微下降屬于氣孔限制,同時(shí)蒸騰速率(Tr)顯著增加(P＜0.01)表明大氣汞對(duì)水稻的蒸騰生理功能有一定的影響。乳熟期水稻葉片氣體交換參數(shù)與大氣汞濃度無顯著差異(P＞0.05),且各指標(biāo)均低于揚(yáng)花期。水稻葉片脯氨酸(Pro)含量在拔節(jié)期隨大氣汞濃度的升高而顯著增加(P＜0.05),揚(yáng)花期先升高后下降,在45 ng·m-3時(shí)達(dá)到最大,成熟期無顯著差異(P＞0.05)；水稻葉片丙二醛(MDA)含量在拔節(jié)期先升高后下降,45 ng·m-3時(shí)達(dá)到最大,揚(yáng)花期和成熟期均無顯著差異(P＞0.05)；水稻葉片超氧化物歧化酶(SOD)活性在拔節(jié)期先升高后下降,15 ng·m-3時(shí)達(dá)到最大,揚(yáng)花期無顯著差異(P＞0.05)。以上結(jié)果表明大氣汞濃度的升高可以引起水稻葉片膜脂過氧化以及脯氨酸和丙二醛含量的積累,且隨著體內(nèi)Pro、MDA和SOD對(duì)大氣汞脅迫的協(xié)同反應(yīng),水稻對(duì)逆境的適應(yīng)能力增強(qiáng),對(duì)汞脅迫產(chǎn)生了耐受性。

氣態(tài)單質(zhì)汞；氣體交換參數(shù)；脯氨酸；丙二醛；超氧化物歧化酶；開頂式氣室

自工業(yè)革命以來,人類活動(dòng)將數(shù)千噸的汞以氣態(tài)元素汞(gaseous elemental mercury,GEM)的形式排放到大氣中[15],隨大氣傳輸擴(kuò)散并通過干濕過程沉降到土壤、植物表面,進(jìn)而對(duì)生物體產(chǎn)生毒害作用,據(jù)報(bào)道,當(dāng)前大氣汞的沉降速率是工業(yè)革命前的3.4倍[16]。目前國(guó)內(nèi)外大量工作關(guān)注于水培或土培實(shí)驗(yàn)中Hg2+對(duì)植物根、葉及幼苗的生理生化影響研究[2,4,6,17],而大氣汞對(duì)植物生理的直接影響研究相對(duì)缺乏。大量研究表明,植物葉片中汞的含量與大氣汞濃度顯著正相關(guān)[18-21],因此本文通過大田開頂式氣室熏氣實(shí)驗(yàn),研究了大氣汞濃度升高對(duì)水稻葉片氣體交換參數(shù)、脯氨酸、丙二醛的積累以及超氧化物歧化酶活性的影響。

1 材料與方法(Materials and methods)

1.1 開頂式氣室(OTCs)熏氣實(shí)驗(yàn)設(shè)計(jì)

實(shí)驗(yàn)地點(diǎn)位于湖南農(nóng)業(yè)大學(xué)農(nóng)資系實(shí)驗(yàn)基地(28.28°N,113.01°E),實(shí)驗(yàn)田面積30 m×10 m,該地區(qū)屬于典型亞熱帶季風(fēng)濕潤(rùn)氣候區(qū),季節(jié)變化明顯,年均氣溫17.2℃,供試水稻為該地區(qū)廣泛播種的中青優(yōu)2號(hào)。

開頂式氣室為Heagle型[22],主要由氣室主體、GEM生成系統(tǒng)和布?xì)庀到y(tǒng)三部分組成,可以為植物提供比較接近自然的生長(zhǎng)環(huán)境。氣室主體為長(zhǎng)1.5 m,寬1.4 m,高1 m(地面以上部分)的長(zhǎng)方體,頂部架設(shè)一個(gè)收縮角度為45°的平截頭體[23],總體積約為2.835 m3。氣室骨架由PVC管連接構(gòu)成,四面緊密覆蓋0.08 mm厚的透明聚氯乙烯塑料薄膜。在一根上部直徑2 cm、長(zhǎng)40 cm,下部直徑4 cm、長(zhǎng)10 cm的玻璃管底部加入少量液態(tài)元素汞(liquid elemental mercury,LEM)沒入恒溫槽液面以下,設(shè)定恒溫槽溫度在20℃左右,為GEM均勻穩(wěn)定的產(chǎn)生提供接近恒溫且低于環(huán)境溫度的條件。產(chǎn)生的GEM由一定流量的載氣(高純氮?dú)?通過內(nèi)徑2 mm的聚四氟塑料管帶出玻璃管并引至田間,與鼓風(fēng)機(jī)產(chǎn)生的氣流相混合,再由密布小孔的PVC管從底部通入氣室[24]。

根據(jù)城市大氣平均汞含量及實(shí)驗(yàn)區(qū)近地表大氣背景汞濃度,本實(shí)驗(yàn)共設(shè)4組汞濃度水平,分別為(5 ±2)ng·m-3(CK)、(15～20)ng·m-3、(45～50)ng·m-3和(90～100)ng·m-3,每個(gè)水平3個(gè)重復(fù)。為避免相互遮蔭,各氣室之間留有3 m的間距。氣室內(nèi)汞濃度通過浮子流量計(jì)調(diào)節(jié)載氣流速來控制,每50 s左右氣室由離心鼓風(fēng)機(jī)(690 m3·h-1)完成1次徹底換氣。從2013-08-31正式開始熏氣,到2013-11-15結(jié)束熏氣,24 h連續(xù)供氣,氣室內(nèi)汞濃度由RA-915+賽曼原子吸收汞分析儀(Lumex Inc.,Russia)在線監(jiān)測(cè)。

1.2 葉片生理指標(biāo)的測(cè)定

1.2.1 氣體交換參數(shù)的測(cè)定

利用LI-6400便攜式光合儀測(cè)定系統(tǒng)(LI-6400, LICOR Inc.,USA)測(cè)定不同汞濃度水平熏氣實(shí)驗(yàn)中水稻葉片凈光合速率(Pn)、氣孔導(dǎo)度(Gs)、胞間CO2濃度(Ci)和蒸騰速率(Tr)4個(gè)氣體交換參數(shù)[25-26]。實(shí)驗(yàn)表明植物葉片Pn一般在上午9:00-11:00達(dá)到最大值[27-28],因此本研究分別選擇揚(yáng)花期和乳熟期天氣狀況基本一致的2 d,在上午10:00-12:00對(duì)水稻葉片氣體交換參數(shù)進(jìn)行測(cè)定,儀器CO2濃度和流速分別設(shè)定為400μmol·mol-1和500μmol·s-1,每個(gè)處理選擇4片完整無缺的劍葉進(jìn)行測(cè)定。

2.3.2推進(jìn)農(nóng)作物秸稈資源化利用 指導(dǎo)長(zhǎng)江經(jīng)濟(jì)帶以縣為單元編制全量化利用實(shí)施方案，提高秸稈綜合利用的區(qū)域統(tǒng)籌水平。堅(jiān)持農(nóng)用為主、五料并舉，積極推廣深翻還田、撿拾打捆、秸稈離田多元利用等技術(shù)，指導(dǎo)創(chuàng)設(shè)秸稈還田離田利用政策機(jī)制，培育秸稈資源化利用產(chǎn)業(yè)化龍頭企業(yè)，推進(jìn)秸稈產(chǎn)業(yè)化發(fā)展。

1.2.2 抗逆指標(biāo)的測(cè)定

采集水稻拔節(jié)期、揚(yáng)花期和成熟期的葉片鮮樣,用便攜式冰箱迅速帶回實(shí)驗(yàn)室,并先后用自來水和去離子水沖洗干凈。葉片游離脯氨酸(Pro)和丙二醛(MDA)含量的測(cè)定參照朱廣廉[29]、陳建勛[30]的方法,脯氨酸含量采用磺基水楊酸提取,酸性茚三酮染色的方法進(jìn)行測(cè)定；丙二醛含量采用硫代巴比妥酸(TBA)法測(cè)定；葉片總超氧化物歧化酶(T-SOD)活性采用黃嘌呤自氧化法(羥胺法)測(cè)定[31]。

2 結(jié)果(Results)

2.1 大氣汞對(duì)水稻葉片氣體交換參數(shù)的影響

實(shí)驗(yàn)結(jié)果表明,在3個(gè)熏氣汞濃度下,揚(yáng)花期水稻葉片凈光合速率(Pn)和氣孔導(dǎo)度(Gs)均比對(duì)照略低(圖1A、B),Pn在15和45 ng·m-3的大氣汞濃度下顯著低于對(duì)照(P＜0.05),但Gs在不同大氣汞濃度下無顯著差異(P＞0.05),說明在實(shí)驗(yàn)處理水平下的大氣汞對(duì)水稻葉片的氣孔開放程度無明顯影響,對(duì)光合作用有一定影響；胞間CO2濃度(Ci)隨大氣汞濃度的升高有明顯降低的趨勢(shì)(圖1C,P＜0.05)；蒸騰速率(Tr)隨大氣汞濃度升高而顯著增加(圖1D,P＜0.01)。乳熟期水稻葉片Pn在45 ng·m-3的大氣汞濃度下顯著低于對(duì)照,Gs、Ci和Tr與大氣汞濃度均無顯著差異(圖1A、B、C、D,P＞0.05)；同時(shí),除Ci與揚(yáng)花期無顯著差異外,乳熟期Pn、Gs和Tr在4個(gè)大氣汞濃度水平下明顯低于揚(yáng)花期,表明乳熟期水稻葉片的光合作用和蒸騰作用較揚(yáng)花期弱,且大氣汞對(duì)乳熟期水稻葉片氣體交換參數(shù)均無明顯影響。

2.2 大氣汞對(duì)水稻葉片脯氨酸含量的影響

拔節(jié)期水稻葉片中脯氨酸含量隨大氣汞濃度的升高而顯著增加(圖2,P＜0.05),揚(yáng)花期和成熟期水稻葉片中游離脯氨酸含量隨大氣汞濃度的升高均有增加的趨勢(shì),表明大氣汞濃度的升高會(huì)脅迫水稻葉片產(chǎn)生并積累大量的游離脯氨酸。大氣汞濃度在5、15和45 ng·m-3時(shí),揚(yáng)花期葉片中脯氨酸含量明顯高于拔節(jié)期和成熟期,在90 ng·m-3的大氣汞濃度下,葉片中脯氨酸含量關(guān)系為:成熟期＞揚(yáng)花期＞拔節(jié)期,表明環(huán)境濃度下的大氣汞對(duì)水稻揚(yáng)花期葉片中游離脯氨酸的積累影響更大,而在高汞濃度下,汞在葉片中隨生長(zhǎng)時(shí)期的延長(zhǎng)而富集對(duì)脯氨酸的積累影響更大。

2.3 大氣汞對(duì)水稻葉片丙二醛含量的影響

水稻葉片中丙二醛(MDA)含量在各生長(zhǎng)時(shí)期隨著大氣汞濃度的升高無顯著差異(圖3,P＞0.05),但在拔節(jié)期和成熟期會(huì)隨大氣汞濃度從5 ng·m-3升高到45 ng·m-3而不斷增加,在90 ng·m-3時(shí)又下降,表明大氣汞濃度的升高會(huì)脅迫葉片產(chǎn)生過多的丙二醛。在4個(gè)大氣汞濃度水平下,不同時(shí)期葉片中MDA含量關(guān)系均為:拔節(jié)期＞成熟期＞揚(yáng)花期,拔節(jié)期明顯最高,且在15和45 ng·m-3時(shí),葉片內(nèi)MDA含量顯著高于對(duì)照(P＜0.05),表明大氣汞對(duì)水稻拔節(jié)期葉片中丙二醛含量的影響最大。

圖1 大氣汞對(duì)水稻葉片氣體交換參數(shù)的影響Fig.1 Effects of air Hg to gas exchange parameters of rice foliage

圖2 大氣汞對(duì)水稻葉片脯氨酸含量的影響Fig.2 Effects of air Hg to proline of rice foliage

圖3 大氣汞對(duì)水稻葉片丙二醛(MDA)含量的影響Fig.3 Effects of air Hg to malonaldehyde(MDA)of rice foliage

2.4 大氣汞對(duì)水稻葉片超氧化物歧化酶活性的影響

水稻葉片中總超氧化物歧化酶(T-SOD)的活性在拔節(jié)期和揚(yáng)花期隨著大氣汞濃度的升高均無顯著差異(圖4,P＞0.05),但在15 ng·m-3時(shí)拔節(jié)期葉片中SOD活性顯著高于其他汞濃度下(P＜0.05)；在5、15和45 ng·m-3時(shí),拔節(jié)期葉片中SOD活性均較揚(yáng)花期高,而在90 ng·m-3時(shí),揚(yáng)花期較拔節(jié)期略高。

圖4 大氣汞對(duì)水稻葉片超氧化物歧化酶活性(SOD)的影響Fig.4 Effects of air Hg to superoxide dismutase(SOD) of rice foliage

3 討論(Discussion)

大量實(shí)驗(yàn)結(jié)果表明,汞影響植物的光合作用,影響光反應(yīng)和暗反應(yīng)[32-33],但也有一些實(shí)驗(yàn)結(jié)果表明,水培實(shí)驗(yàn)中汞濃度低于10mg·L-1時(shí),汞對(duì)植物的光合作用影響較小甚至無影響[32,34-37]。Ericksen和Gustin[34]的實(shí)驗(yàn)結(jié)果表明,不同濃度的大氣汞(2.4、11和30 ng·m-3)熏蒸對(duì)楊樹葉的Pn和Gs均無顯著影響,Niu等[38]的實(shí)驗(yàn)結(jié)果也表明,環(huán)境濃度的大氣汞(2、10、20和50 ng·m-3)對(duì)玉米葉片的氣體交換參數(shù)基本沒有影響。Ci的變化是分析植物氣孔與非氣孔限制的基礎(chǔ),作為光合過程中CO2的中介,一方面受到作為源的外界CO2濃度和氣孔導(dǎo)度的影響,另一方面又受葉片光合消耗的影響[26,39],而非氣孔限制常用于解釋胞內(nèi)恒定或者增加的Ci[40-41],本實(shí)驗(yàn)中揚(yáng)花期Ci隨著大氣汞濃度的升高明顯下降,且Pn和Gs均有一定程度的降低,說明水稻揚(yáng)花期屬于氣孔限制。王孟本等[42]對(duì)河北楊和檸條的研究表明,在土壤水分充足的條件下,若樹木根系吸水力依然較強(qiáng),而其蒸騰生理調(diào)控力卻大為減弱,蒸騰速率就會(huì)異常增大,本實(shí)驗(yàn)中隨著大氣汞濃度的升高,水稻葉片光合作用和氣孔導(dǎo)度均無顯著變化,而蒸騰速率卻線性升高,說明大氣汞影響了水稻葉片的蒸騰生理功能。

脯氨酸(Pro)是植物蛋白質(zhì)的組分之一,可以游離狀態(tài)廣泛存在于植物體中,在逆境(旱、鹽堿、熱、冷、凍等)脅迫條件下,許多植物體內(nèi)脯氨酸含量顯著增加,在一定程度上反映了植物的抗逆性。實(shí)驗(yàn)表明,重金屬脅迫下植物體內(nèi) Pro濃度會(huì)增加[11-12,43]。劉玲等[44]的砂培實(shí)驗(yàn)結(jié)果表明,在低汞濃度、短時(shí)間內(nèi),玉米體內(nèi)Pro含量有上升趨勢(shì),在高汞濃度、長(zhǎng)時(shí)間內(nèi),玉米體內(nèi)Pro含量會(huì)嚴(yán)重下降,且Pro對(duì)汞的脅迫非常敏感；Niu等[38]對(duì)玉米的研究結(jié)果表明,大氣汞濃度與Pro含量之間無顯著相關(guān)性(P＞0.05),但在大氣汞濃度為20和50 ng·m-3時(shí)Pro含量顯著高于對(duì)照(P＜0.05)。本實(shí)驗(yàn)中,在15和45 ng·m-3大氣汞濃度下?lián)P花期葉片脯氨酸含量顯著較高,而在90 ng·m-3時(shí)成熟期葉片脯氨酸含量顯著較高,表明隨著大氣汞濃度的升高,水稻葉片脯氨酸含量隨著大氣汞濃度的升高均有不同程度的增加。

在植物器官衰老或在逆境條件下,細(xì)胞內(nèi)會(huì)產(chǎn)生大量的活性自由基,并與脂質(zhì)發(fā)生過氧化反應(yīng),最終產(chǎn)物即為丙二醛(MDA),通常利用它作為脂質(zhì)過氧化指標(biāo),表示細(xì)胞膜脂過氧化程度和植物對(duì)逆境條件反應(yīng)的強(qiáng)弱。大量實(shí)驗(yàn)結(jié)果表明,重金屬脅迫下植物體內(nèi)丙二醛的含量會(huì)增加[6,45-46]。Cho和Park[6]報(bào)道西紅柿葉中MDA水平隨葉汞濃度的增加而增加,Moreno-Jimeˊnez等[47]對(duì)2種野生植物的研究結(jié)果也表明葉中MDA含量與葉汞濃度顯著正相關(guān)(P＜0.05)；而Niu等[38]對(duì)玉米的研究結(jié)果表明,大氣汞濃度與MDA含量之間無顯著相關(guān)性(P＞0.05),僅在大氣汞濃度為20和50 ng·m-3時(shí)MDA含量顯著高于對(duì)照(P＜0.05)。本實(shí)驗(yàn)中,高濃度的大氣汞熏氣顯著增加了丙二醛的含量,表明會(huì)引起植物葉的膜脂過氧化。

超氧化物歧化酶(SOD)是機(jī)體內(nèi)天然存在的超氧自由基清除因子,是生物體內(nèi)清除自由基的首要物質(zhì),與體內(nèi)的過氧化氫酶(CAT)和過氧化物酶(POD)組成了一個(gè)完整的防氧化鏈條。大量實(shí)驗(yàn)結(jié)果表明重金屬脅迫下植物體內(nèi)SOD活性會(huì)發(fā)生變化[12,45,48-49]。馬成倉(cāng)[44]用不同濃度的HgCl2溶液灌溉油菜結(jié)果顯示,油菜葉細(xì)胞內(nèi)SOD活性在0.5mg·L-1的汞濃度下無明顯變化,(1～10)mg·L-1的汞濃度下逐漸升高,50mg·L-1時(shí)持續(xù)下降；陸海燕等[12]的研究結(jié)果顯示,隨著溶液中Cd2+濃度的增加,蘆葦葉片中SOD活性呈先上升后下降的趨勢(shì)；施國(guó)新等[49]的研究也表明,隨著汞濃度的升高,滿江紅葉片SOD活性逐漸增強(qiáng),當(dāng)濃度超過一定范圍時(shí),SOD活性則開始降低。本實(shí)驗(yàn)中,拔節(jié)期水稻葉片SOD活性隨大氣汞濃度的升高先上升后下降,15 ng·m-3時(shí)達(dá)到最大,表明水稻體內(nèi)氧自由基清除能力較強(qiáng),水稻耐汞性較好。

綜上分析,水稻葉片中Pro、MDA含量和SOD活性隨著大氣汞濃度的升高變化不同。在拔節(jié)期, Pro含量隨大氣汞濃度升高呈線性增加,MDA含量先急劇增加然后降低,在45 ng·m-3的汞濃度下達(dá)到最大,SOD活性先增大,在15 ng·m-3的汞濃度下達(dá)到最大后又開始下降；在揚(yáng)花期,Pro含量隨大氣汞濃度的升高先增加后下降,且明顯比拔節(jié)期高, MDA含量和SOD活性無顯著變化,且較拔節(jié)期低。出現(xiàn)這種情況的可能原因是,汞脅迫下水稻葉片細(xì)胞膜脂出現(xiàn)過氧化,體內(nèi)SOD活性被激發(fā),同時(shí)Pro和MDA含量增加,Pro具有減少膜脂過氧化和穩(wěn)定細(xì)胞膜結(jié)構(gòu)及生物大分子的作用[50],因此對(duì)SOD這種生物蛋白大分子具有一定的保護(hù)作用,對(duì)其他膜結(jié)構(gòu)也有一定的保護(hù)作用,Pro的這種雙重作用機(jī)制,使得SOD活性在迅速升高后又恢復(fù)到正常水平,并隨著Pro的不斷增加,MDA含量也開始下降；隨著生長(zhǎng)期的延長(zhǎng),汞脅迫使水稻體內(nèi)Pro含量升高,同時(shí)對(duì)逆境適應(yīng)能力增強(qiáng),對(duì)汞污染產(chǎn)生了耐受性,體內(nèi)Pro含量開始降低。這與陸海燕等[12]在鎘污染下對(duì)蘆葦葉片丙二醛、脯氨酸及SOD保護(hù)酶反應(yīng)的研究結(jié)果一致。因此,水稻葉片中Pro、MDA和SOD對(duì)大氣汞濃度升高有協(xié)同反應(yīng)。

[1]沈盎綠.Hg2+對(duì)細(xì)葉蜈蚣草的毒害效應(yīng)[D].西南農(nóng)業(yè)大學(xué),2004

[2]詹嘉紅,藍(lán)宗輝.汞對(duì)水稻幼苗部分生理生化指標(biāo)的影響[J].生物技術(shù),2007,17(3):76-77 Zhan J H,Lan Z H.Effects of mercury on some of physiological indicators of rice seedlings[J].Chinese Journal of Biotechnology,2007,17(3):76-77(in Chinese)

[3]Patra M,Sharma A.Mercury toxicity in plants[J].The Botanical Review,2000,66(3):379-422

[4]Lu C M,Chau C W,Zhang J H.Acute toxicity of excess mercury on the photosynthetic performance of cyanobacterium,S.platensis--assessment by chlorophyll fluorescence analysis[J].Chemosphere,2000,41(1-2):191-196

[5]王琳,王林嵩,王麗,等.Hg2+脅迫對(duì)小麥幼苗POD、CAT和SOD同工酶的影響[J].安徽農(nóng)業(yè)科學(xué),2008,36 (35):15326-15328,15338 Wang L,Wang L H,Wang L,et al.Effect of Hg2+on isozymes of peroxidase,catalaseand and superoxide diamutase in wheat seedling[J].Journal of Anhui Agricultural Sciences,2008,36(35):15326-15328,15338(in Chinese)

[6]Cho U H,Park J O.Mercury-induced oxidative stress in tomato seedlings[J].Plant Science,2000,156(1):1-9

[7]Han Y,Xuan W,Yu T,et al.Exogenoushematin alleviates mercury‐ induced oxidative damage in the roots of medicago sativa[J].Journal of Integrative Plant Biology, 2007,49(12):1703-1713

[8]Clijsters H,VanAssche F.Inhibition of photosynthesis by heavy metals[J].Photosynthesis Research,1985,7(1):31-40

[9]Laliberté G,Hellebust J A.Regulation of proline content ofChlorella autotrophicain response to changes in salinity[J].Canadian Journal of Botany,1989,67(7):1959-1965

[10]Zengin F K,Munzuroglu O.Effects of some heavy metals on content of chlorophyll,proline and some antioxidant chemicals in bean(Phaseolus vulgarisL.)seedlings[J]. Acta Biologica Cracoviensia Series Botanica,2005,47(2): 157-164

[11]Zhang L P,Mehta S K,Liu Z P,et al.Copper-induced proline synthesis is associated with nitric oxide generation inChlamydomonas reinhardtii[J].Plant and Cell physiology,2008,49(3):411-419

[12]陸海燕,劉志輝,呂光輝.鎘污染下蘆葦葉片丙二醛、脯氨酸及SOD保護(hù)酶反應(yīng)研究[J].干旱區(qū)資源與環(huán)境,2013,27(8):171-175 Lu H Y,Liu Z H,Lv G H.Reaction of MDA,proline and SOD under Cd stress in mixture ofPhragmites australis's stems and leaves[J].Journal of Arid Land Resources and Environment,2013,27(8):171-175(in Chinese)

[13]Janero D R.Malondialdehyde and thiobarbituric acid-reactivity as diagnostic indices of lipid peroxidation and peroxidative tissue injury[J].Free Radical Biology and Medicine,1990,9(6):515-540

[14]劉惠芬,高大翔,馬勇.汞脅迫對(duì)水稻生長(zhǎng)及幼苗生理生化的影響[C].第二屆全國(guó)農(nóng)業(yè)環(huán)境科學(xué)學(xué)術(shù)研討會(huì)論文集,2007,7:16-19 Liu H F,Gao D X,Ma Y.Effects of Hg stress on growth and physiological and biochemical characteristics of rice seedlings[C].The Second National Agricultural Academic Conference on Environmental Sciences,2007,7:16-19 (in Chinese)

[15]Pirrone N,Cinnirella S,Feng X B,et al.Global mercury emissions to the atmosphere from anthropogenic and natural sources[J].Atmospheric Chemistry and Physics, 2010,10(13):5951-5964

[16]Swain E B,Engstrom D R,Brigham M E,et al.Increasing rates of atmospheric mercury deposition in midcontinental North America[J].Science,1992,257(5071):784-787

[17]瞿愛權(quán),東惠如,李俊國(guó).汞對(duì)水稻、油菜影響的研究初報(bào)[J].環(huán)境科學(xué),1980,1(6):50-52

[18]Ericksen J,Gustin M,Schorran D,et al.Accumulation of atmospheric mercury in forest foliage[J].Atmospheric Environment,2003,37(12):1613-1622

[19]Millhollen A G,Gustin M S,Obrist D.Foliar mercury accumulation and exchange for three tree species[J].Environmental Science&Technology,2006,40(19):6001-6006

[20]Niu Z C,Zhang X S,Wang Z W,et al.Field controlled experiments of mercury accumulation in crops from air and soil[J].Environmental Pollution,2011,159(10): 2684-2689

[21]Niu Z C,Zhang X S,Wang S,et al.The linear accumulation of atmospheric mercury by vegetable and grass leaves:Potential biomonitors for atmospheric mercury pollution[J].Environmental Science and Pollution Research, 2013,20(9):6337-6343

[22]Heagle A S,Body D E,Heck W W.An open-top field chamber to assess the impact of air pollution on plants[J]. Journal of Environmental Quality,1973,2(3):365-368

[23]王春乙.OTC-1型開頂式氣室的結(jié)構(gòu)和性能與國(guó)內(nèi)外同類氣室的比較[J].環(huán)境科學(xué)進(jìn)展,1996,4(1):50-57 Wang C Y.The structure and function comparison between OTC-1 open top chamber with the similar one in home and overseas[J].Chinese Journal of Advances in Environmental Sciences,1996,4(1):50-57(in Chinese)

[24]Mandl R,Weinstein L,McCune D,et al.A cylindrical, open-top chamber for the exposure of plants to air pollutants in the field[J].Journal of Environmental Quality, 1973,2(3):371-376

[25]王建林,于貴瑞,王伯倫,等.北方粳稻光合速率,氣孔導(dǎo)度對(duì)光強(qiáng)和 CO2濃度的響應(yīng)[J].植物生態(tài)學(xué)報(bào), 2005,29(1):16-25 Wang J L,Yu G R,Wang B L,et al.Response of photosynthetic rate and stomatal conductance of rice to light intensity and CO2concentration in northern china[J].Chinese Journal of Acta Phytoecologica Sinica,2005,29(1): 16-25(in Chinese)

[26]徐俊增,彭世彰,魏征,等.節(jié)水灌溉水稻葉片胞間CO2濃度及氣孔與非氣孔限制[J].農(nóng)業(yè)工程學(xué)報(bào),2010, 26(7):76-80 Xu J Z,Peng S Z,Wei Z,et al.Intercellular CO2concentration and stomatal or non-stomatal limitation of rice under water saving irrigation[J].Transactions of the CSAE, 2010,26(7):76-80(in Chinese)

[27]He J,Austin P T,Nichols M A,et al.Elevated root-zone CO2protects lettuce plants from midday depression of photosynthesis[J].Environmental and Experimental Botany,2007,61(1):94-101

[28]Wang J,Yu Q,Li J,et al.Simulation of diurnal variations of CO2,water and heat fluxes over winter wheat with a model coupled photosynthesis and transpiration[J].Agricultural and Forest Meteorology,2006,137(3):194-219

[29]朱廣廉,鐘誨文,張愛琴.植物生理學(xué)實(shí)驗(yàn)[M].北京:北京大學(xué)出版社,1990:245-252

[30]陳建勛,王曉峰.植物生理學(xué)實(shí)驗(yàn)指導(dǎo)(第二版)[M].廣州:華南理工大學(xué)出版社,2002:66-74

[31]黎瑞珍,楊慶建,陳貽銳.超氧化物歧化酶(SOD)活性的測(cè)定及其應(yīng)用研究[J].瓊州大學(xué)學(xué)報(bào),2005,11(5): 34-36 Li R Z,Yang Q J,Chen Y R.Study of determination of superoxide dismutase(SOD)activation and application [J].Chinese Journal of Qiongzhou University,2005,11 (5):34-36(in Chinese)

[32]Baszynski T,Krupa Z.Some aspects of heavy metals toxicity towards photosynthetic apparatus-direct and indirect effects on light and dark reactions[J].Acta Physiologiae Plantarum,1995,17(2):177-190

[33]Pisani T,Munzi S,Paoli L,et al.Physiological effects of mercury in the lichensCladonia arbusculasubsp.Mitis (Sandst.)Ruoss andPeltigera rufescens(Weiss)Humb[J]. Chemosphere,2011,82(7):1030-1037

[34]Ericksen J A,Gustin M S.Foliar exchange of mercury as a function of soil and air mercury concentrations[J].Science of the Total Environment,2004,324(1-3):271-279

[35]Bernier M,Popovic R,Carpentier R.Mercury inhibition at the donor side of photosystem II is reversed by chloride[J].FEBS Letters,1993,321(1):19-23

[36]?er?eň F,Král'ová K,Bumbalova A.Action of mercury on the photosynthetic apparatus of spinach chloroplasts[J].Photosynthetica,1998,35(4):551-559

[37]Israr M,Sahi S,Datta R,et al.Bioaccumulation and physiological effects of mercury inSesbania drummondii[J]. Chemosphere,2006,65(4):591-598

[38]Niu Z C,Zhang X S,Wang S,et al.Field controlled experiments on the physiological responses of maize(Zea maysL.)leaves to low-level air and soil mercury exposures[J].Environmental Science and Pollution Research, 2014,21(2):1541-1547

[39]傅偉,王天鐸.一個(gè)氣孔對(duì)環(huán)境因子響應(yīng)的機(jī)理性數(shù)學(xué)模型[J].植物生理學(xué)報(bào),1994,20(3):277-284 Fu W,Wang T D.A mechanistic model of stomatal responses to environmental factors[J].Chinese Journal of Acta Phytophysiologica Sinica,1994,20(3):277-284(in Chinese)

[40]Farquhar G D,Sharkey T D.Stomatal conductance and photosynthesis[J].Annual Review of Plant Physiology, 1982,33(1):317-345

[41]劉俊祥,孫振元,巨關(guān)升,等.重金屬Cd2+對(duì)結(jié)縷草葉片光合特性的影響[J].核農(nóng)學(xué)報(bào),2009,23(6):1050-1053 Liu J X,Sun Z Y,Ju G S,et al.Effects of Cd2+stress on photosynthetic characteristics in leaves ofZoysia japonica [J].Chinese Journal of Nuclear Agricultural Sciences, 2009,23(6):1050-1053(in Chinese)

[42]王孟本,李洪建,柴寶峰,等.樹種蒸騰作用,光合作用和蒸騰效率的比較研究[J].植物生態(tài)學(xué)報(bào),1999,23(5): 401-410 Wang M B,Li H J,Chai B F,et al.A comparison of transpiration,photosynthesis and transpiration efficiency in four tree species in loess region[J].Chinese Journal of Acta Phytoecologica Sinica,1999,23(5):401-410(in Chinese)

[43]Radic'S,Babic'M,?kobic'D,et al.Ecotoxicological effects of aluminum and zinc on growth and antioxidants in Lemna minorL[J].Ecotoxicology and Environmental Safety,2010,73(3):336-342

[44]劉玲,楊雙春,張洪林.Hg2+脅迫下玉米生理生態(tài)變化的研究[J].生態(tài)環(huán)境,2004,13(2):161-163 Liu L,Yang S C,Zhang H L.Physiological and ecological response of maize to mercury stress[J].Chinese Journal of Ecology and Environment,2004,13(2):161-163(in Chinese)

[45]馬成倉(cāng).Hg對(duì)油菜葉細(xì)胞膜的損傷及細(xì)胞的自身保護(hù)作用[J].應(yīng)用生態(tài)學(xué)報(bào),1998,9(3):323-326 Ma C C.Hg harm on cell membrane of rape leaf and cell endogenous protection effect[J].Chinese Journal of Applied Ecology,1998,9(3):323-326(in Chinese)

[46]Cargnelutti D,Tabaldi L A,Spanevello R M,et al.Mercury toxicity induces oxidative stress in growing cucumber seedlings[J].Chemosphere,2006,65(6):999-1006

[47]Moreno-Jiménez E,Gamarra R,Carpena-Ruiz R,et al. Mercury bioaccumulation and phytotoxicity in two wild plant species of Almadén area[J].Chemosphere,2006,63 (11):1969-1973

[48]張利紅,李培軍,李雪梅,等.鎘脅迫對(duì)小麥幼苗生長(zhǎng)及生理特性的影響[J].生態(tài)學(xué)雜志,2005,24(4):458-460 Zhang L H,Li P J,Li X M,et al.Effects of cadmium stress on the growth and physiological characteristics of wheat seedlings[J].Chinese Journal of Ecology,2005,24 (4):458-460(in Chinese)

[49]Shi G X,Xu Q S,Xie K B,et al.Physiology and ultrastructure ofAzolla imbricataas affected by Hg2+and Cd2+Toxicity[J].Acta Botanica Sinica,2003,45(4):437-444

[50]蔣明義,郭紹川.氧化脅迫下稻苗體內(nèi)積累的脯氨酸的抗氧化作用[J].植物生理學(xué)報(bào),1997,23(4):347-352 Jiang M Y,Guo S C.Proline accumulation in rice seedlings exposed to oxidative stress in relation to antioxidation[J].Chinese Journal of Acta Phytophysiologica Sinica,1997,23(4):347-352(in Chinese)

Physiological Responses of Rice Leaves to the Elevated Gaseous Elemental Mercury in the Atmosphere

Chen Jian1,2,Wang Zhangwei1,*,Zhang Xiaoshan1,Qin Pufeng3,Lu Haijun3
1.Laboratory of Atmospheric Environmental Sciences,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China
2.College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100049,China
3.College of Resources&Environment,Hunan Agricultural University,Changsha 410128,China

27 January 2015 accepted 25 March 2015

The effects of elevated gaseous elemental mercury(GEM)on gas exchange parameters,accumulation of proline(Pro)and malondialdehyde(MDA),activity of superoxide dismutase(SOD)in rice foliage were studied with field open-top chambers(OTCs)fumigation experiment.The results showed that the net photosynthesis rate(Pn)and stomatal conductance(Gs)were less slightly in GEM treatment than those in the control,which indicating that elevated GEM had some effect on photosynthesis and stomatal openness of rice leaves.In flowering stage of rice,the distinct decrease(P＜0.05)of intercellular CO2concentration(Ci)with elevated GEM indicated that stomatal limitation led to the slight decrease of Pn,and the significant increase(P＜0.01)of transpiration rate(Tr)with elevated GEM showed that the physiological function of rice transpiration was effected by Hg in the atmosphere.Gas exchange parameters of rice leaves in milky stage were insignificantly difference with GEM in air(P＞0.05)and lower than that in flowering stage.Proline concentrations in rice foliage were increased obviously with elevated GEM(P＜0.05)in jointing stage,declined after increasing and reached to the maximum value at 45 ng·m-3in flowering stage,and it was no significant difference(P＞0.05)in mature stage among four treatments.The contents of MDA in rice foliage increased first and reached the highest value at 45 ng·m-3,and then decreased in jointing stage,and it was no significant difference(P＞0.05)with the increase of GEM in flowering and mature stage.The activity of SOD in rice foliage also increased first and then declined at 15 ng·m-3in jointing stage,and there was no significant difference(P＞0.05)in flowering stage.These results suggested that elevated GEM in air can cause membrane lipid peroxidation and accumulation of Pro and MDA in rice foliage,furthermore the ability of adapting to adversity and the tolerance to elevated GEM for rice were enhanced with the concerted reactions in vivo among Pro,MDA and SOD on the atmospheric mercury stress.

GEM;gas exchange parameters;proline;malondialdehyde;superoxide dismutase;open-top chamber

2015-01-27 錄用日期:2015-03-25

1673-5897(2016)1-133-08

X171.5

A

10.7524/AJE.1673-5897.20150127003

陳劍,王章瑋,張曉山,等.大氣汞濃度升高對(duì)水稻葉片生理效應(yīng)的影響研究[J].生態(tài)毒理學(xué)報(bào),2016,11(1):133-140

Chen J,Wang Z W,Zhang X S,et al.Physiological responses of rice leaves to the elevated gaseous elemental mercury in the atmosphere[J].Asian Journal of Ecotoxicology,2016,11(1):133-140(in Chinese)

國(guó)家自然科學(xué)基金項(xiàng)目(No.41373124,41073092)；國(guó)家重大基礎(chǔ)研究(973)計(jì)劃項(xiàng)目(2013CB430002)

陳劍(1990-),男,碩士研究生,研究方向?yàn)榇髿夤h(huán),E-mail:chenjianev2008@126.com

),E-mail:wangzhw@rcees.ac.cn

簡(jiǎn)介:王章瑋(1978-)，女，博士，副研究員，主要研究方向大氣汞循環(huán)。