余佳玲， 宋海星， 謝桂先*， 張振華* ， 廖 瓊， 官春云

(1湖南農(nóng)業(yè)大學(xué)資源環(huán)境學(xué)院， 土壤肥料資源高效利用國家工程實(shí)驗(yàn)室， 南方糧油作物協(xié)同創(chuàng)新中心， 農(nóng)田污染控制與農(nóng)業(yè)資源利用湖南省重點(diǎn)實(shí)驗(yàn)室， 植物營養(yǎng)湖南省普通高等學(xué)校重點(diǎn)實(shí)驗(yàn)室， 長沙 410128；2國家油料改良中心湖南分中心， 長沙 410128 )

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不同氮效率油菜SPS和PEPC活性差異及其對籽粒產(chǎn)量與油分含量的影響

余佳玲1， 宋海星1， 謝桂先1*， 張振華1*， 廖 瓊1， 官春云2

(1湖南農(nóng)業(yè)大學(xué)資源環(huán)境學(xué)院， 土壤肥料資源高效利用國家工程實(shí)驗(yàn)室， 南方糧油作物協(xié)同創(chuàng)新中心， 農(nóng)田污染控制與農(nóng)業(yè)資源利用湖南省重點(diǎn)實(shí)驗(yàn)室， 植物營養(yǎng)湖南省普通高等學(xué)校重點(diǎn)實(shí)驗(yàn)室， 長沙 410128；2國家油料改良中心湖南分中心， 長沙 410128 )

【目的】蔗糖磷酸合成酶(sucrose phosphate synthase，SPS)與磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxylase，PEPC)分別控制著植物體內(nèi)的碳骨架向碳代謝和氮代謝的流轉(zhuǎn)，影響作物的產(chǎn)量與品質(zhì)。為探明氮高效油菜品種在高效利用氮素的同時(shí)協(xié)調(diào)籽粒蛋白與油分累積矛盾的機(jī)理，研究了不同氮效率油菜品種的SPS與PEPC活性差異及其對籽粒油分含量的影響?！痉椒ā坎捎猛僚嘣囼?yàn)，以氮高效品種27號(H)與氮低效品種6號(L)為試驗(yàn)材料，在常氮(N)與低氮(S)條件下，研究不同氮效率油菜品種苗期到花期葉片與角果發(fā)育初期的角果、角果發(fā)育中期的角果皮與籽粒中SPS與PEPC活性變化及差異、生長后期碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率以及收獲期籽粒油分含量的差異?！窘Y(jié)果】兩種供氮水平下，氮高效品種27號的產(chǎn)量與籽粒油分含量均顯著高于氮低效品種6號，品種優(yōu)勢明顯；且氮高效品種27號苗期到花期葉片與角果發(fā)育初期的角果、角果發(fā)育中期的角果皮與籽粒中的SPS與PEPC活性均高于氮低效品種6號，兩種供氮水平的規(guī)律相同，但是SPS與PEPC活性的比值(SPS/PEPC)卻因生育期不同而異，營養(yǎng)生長期葉片中氮高效品種27號的SPS/PEPC高于氮低效品種6號，開花期品種間葉片SPS/PEPC相近，角果發(fā)育期主要生殖器官中的SPS/PEPC值氮高效品種反而低于氮低效品種。說明氮高效品種向碳代謝和氮代謝輸送的碳骨架在全生育期均多于氮低效品種，而碳代謝對氮代謝的響應(yīng)只在生育前期強(qiáng)于氮低效品種，生育后期則相反。碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率、籽粒油分含量與產(chǎn)量也是氮高效品種大于氮低效品種，這可能為氮高效品種協(xié)調(diào)籽粒蛋白與油分累積矛盾的重要生理機(jī)制。供氮水平對上述各指標(biāo)有不同的影響，籽粒產(chǎn)量、PEPC活性、碳素轉(zhuǎn)運(yùn)量及轉(zhuǎn)運(yùn)率以常氮處理高于低氮處理，而油分含量、SPS活性及SPS/PEPC以常氮處理低于低氮處理，但不改變以上指標(biāo)的品種間差異?！窘Y(jié)論】與氮低效品種相比，氮高效品種全生育期向碳、氮代謝均輸送更多的碳骨架，這是氮高效品種緩解碳、氮代謝矛盾的重要前提；碳代謝對氮代謝的響應(yīng)生育前期較高、生育后期較低，同時(shí)生育后期有更多營養(yǎng)器官的碳素轉(zhuǎn)運(yùn)到籽粒，也為油菜生育后期滿足籽粒碳、氮代謝所需要的碳骨架，并協(xié)調(diào)籽粒油分與蛋白質(zhì)含量的矛盾提供了條件。

油菜； SPS； PEPC； 碳氮代謝； 籽粒油分

碳與氮是作物體內(nèi)兩大重要元素，參與作物生命活動中化合物的形成，對作物產(chǎn)量與品質(zhì)的形成起重要作用。碳、氮代謝對于作物的生長發(fā)育尤為重要，其最首要的功能是為細(xì)胞的新陳代謝提供碳骨架與能量[1-2]，其中氮代謝可為合成蛋白質(zhì)與核酸等重要生命物質(zhì)提供氮源[3]。碳、氮代謝二者密不可分，其相互作用是作物產(chǎn)量與品質(zhì)的基石[4]，同時(shí)碳、氮代謝作為植物體內(nèi)的兩大主要代謝過程，對代謝途徑所需要的碳骨架與能量存在著明顯的競爭[5]。因此，作物生長過程中調(diào)節(jié)碳和能量的流向，以最大限度地同時(shí)滿足碳、氮代謝的需求，達(dá)到作物優(yōu)質(zhì)高產(chǎn)是十分重要的[6]。研究表明，蔗糖磷酸合成酶(sucrose phosphate synthase, SPS)與磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxylase, PEPC)在碳和能量的流轉(zhuǎn)過程中起重要作用，二者共同調(diào)節(jié)著光合作用固定的碳在糖類與氨基酸之間的分配[7-8]，從而調(diào)節(jié)碳、氮代謝的方向。SPS為植物體蔗糖合成的關(guān)鍵調(diào)控酶，在控制蔗糖合成速率的同時(shí)，平衡光合作用物質(zhì)合成、蔗糖運(yùn)輸與淀粉形成等過程；PEPC具有固定CO2為C3循環(huán)提供碳源的重要作用，同時(shí)PEPC還可促進(jìn)并調(diào)節(jié)有機(jī)酸合成，為氮代謝途徑提供碳骨架和能量[9-10]，在油菜等C3植物中則以后一個(gè)作用為主。油菜是油料作物，碳、氮代謝競爭導(dǎo)致的籽粒蛋白質(zhì)與油分含量之間的矛盾比較突出，較好的氮素營養(yǎng)條件，雖可提高產(chǎn)量和籽粒蛋白質(zhì)含量，但減少籽粒油分含量。因此，如何調(diào)節(jié)油菜碳、氮代謝的關(guān)系，在保證籽粒形成過程所需的基本氮代謝需求的前提下，使碳骨架及時(shí)流向碳代謝方向是人們關(guān)注的問題。陳歷儒等[11]研究表明，氮高效油菜品種并沒有因高效吸收利用氮素而降低油分含量，說明其中存在著較好的碳、氮代謝協(xié)調(diào)機(jī)理，但這一協(xié)調(diào)機(jī)理是否和SPS與PEPC的活性有關(guān)，目前尚未見相關(guān)報(bào)道。本試驗(yàn)對不同氮效率油菜品種的SPS與PEPC酶活性及其與籽粒油分的關(guān)系進(jìn)行研究，以期為揭示油菜碳、氮代謝方向調(diào)節(jié)對籽粒油分形成的影響機(jī)理提供參考。

1　材料與方法

1.1 材料及試驗(yàn)設(shè)計(jì)

試驗(yàn)于2013年9月至2014年3月在湖南農(nóng)業(yè)大學(xué)耘圓基地進(jìn)行，供試土壤為第四紀(jì)紅土母質(zhì)發(fā)育的沖積菜園土，其有機(jī)質(zhì)含量23.08 g/kg、全氮1.53 g/kg、全磷1.33 g/kg、全鉀19.79 g/kg、堿解氮129.0 mg/kg、速效磷79.7 mg/kg、速效鉀137.4 mg/kg、pH 5.18。供試油菜品種為本課題組經(jīng)過大田試驗(yàn)篩選出的氮高效品種27號(No.27)和氮低效品種6號(No.6)，其中氮高效品種的氮素吸收與利用效率以及籽粒中氮素積累量均高于氮低效品種。本試驗(yàn)采用盆栽土培試驗(yàn)，用30 cm×20 cm白瓷缽，每缽裝土6.25 kg，栽植1株，采用育苗移栽方法，于2013年8月25日大田育苗，9月25日移栽，完全隨機(jī)區(qū)組排列。試驗(yàn)設(shè)品種與氮水平兩個(gè)因子，氮水平設(shè)正常供氮與低氮兩個(gè)水平，共4個(gè)處理，分別為：高效品種正常供氮(H-N)；高效品種低氮(H-S)；低效品種正常供氮(L-N)；低效品種低氮(L-S)。每處理重復(fù)24次(每處理每次取樣重復(fù)4次)，共96缽。正常供氮處理每公斤土施N 0.2 g、 P2O50.1 g、 K2O 0.15 g、 B 0.0024 g；低氮處理除不施氮肥外，其余養(yǎng)分施用量與正常供氮處理相同。氮肥用尿素(含N 46%)、磷肥用鈣鎂磷肥(含P2O512%)、鉀肥用氯化鉀(含K2O 60%)、硼肥用硼砂(含B 10.8%)。

1.2取樣及測定方法

分別在油菜苗期、抽薹期、開花期、角果發(fā)育初期、角果發(fā)育中期與收獲期取整株樣品，其中前5個(gè)時(shí)期樣品洗凈、吸干水分后稱鮮重；苗期、抽薹期與開花期取長勢健壯的葉片、角果發(fā)育初期及角果發(fā)育中期選取同一生長梯度的角果用于測定蔗糖磷酸合成酶(sucrose phosphate synthase, SPS)和磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxylase, PEPC)活性，剩余部分烘干，烘干后的所有樣品粉碎過篩測定植株全碳含量；收獲期樣品烘干后測定全碳和籽粒產(chǎn)量與籽粒油分含量。

SPS活性用可見分光光度法測定[12]；PEPC活性用紫外分光光度法測定[13]；籽粒油分含量用索氏提取法測定[14]；植株總碳用Vario PYRO cube元素分析儀 (Elemental公司) 測定。根據(jù)植株總碳測定結(jié)果，以營養(yǎng)器官中總碳累積量最高的生育期為基準(zhǔn)(本試驗(yàn)中為抽薹期)用差減法計(jì)算碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率[15]。計(jì)算公式為:

碳素轉(zhuǎn)運(yùn)量(mg)=抽薹期植株碳素累積量-收獲期營養(yǎng)器官碳素累積量

碳素轉(zhuǎn)運(yùn)率(%)=碳素轉(zhuǎn)運(yùn)量/抽薹期植株碳素累積量×100

1.3數(shù)據(jù)處理

試驗(yàn)數(shù)據(jù)均用Excel和SPSS 15.0專業(yè)版統(tǒng)計(jì)軟件進(jìn)行處理。

2　結(jié)果與分析

2.1不同氮效率油菜籽粒的產(chǎn)量與油分含量

2.1.1 籽粒產(chǎn)量由圖1可以看出，品種與供氮水平對籽粒產(chǎn)量有顯著影響，無論氮水平高低，氮高效品種27號的籽粒產(chǎn)量均顯著高于氮低效品種6號。與正常供氮相比，兩品種均表現(xiàn)為低氮水平下籽粒產(chǎn)量顯著降低。

2.1.2 籽粒油分含量圖2顯示，無論氮水平高低，品種27號的籽粒油分均高于品種6號，差異顯著；不同供氮水平，兩品種均表現(xiàn)為低氮處理時(shí)籽粒油分含量顯著高于正常供氮。即氮高效品種具有更高的油分積累能力，低氮條件下有利于籽粒油分含量的累積，這是因?yàn)槿钡獣r(shí)氮代謝減弱，相應(yīng)地有更多的碳骨架流向碳代謝。但因?yàn)槿钡獣r(shí)籽粒產(chǎn)量下降，總油分產(chǎn)量不會提高。

2.2不同氮效率油菜SPS與PEPC活性的差異

2.2.1 油菜SPS活性SPS是作物碳水化合物積累

圖1　不同氮水平對兩油菜品種籽粒產(chǎn)量的影響Fig.1　Seed yield of the two rape varieties in different nitrogen conditions[注(Note): 柱上不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Different capital letters above the bars indicate that differences between varieties are significant under same nitrogen condition at 5% level；不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平Different lowercase letters above the bars indicate that differences of same variety between nitrogen conditions are significant at 5% level.]

圖2　不同氮水平對兩油菜品種籽粒油分含量的影響Fig.2　Seed oil content of the two rape varieties in different nitrogen conditions[注(Note): 柱上不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Different capital letters above the bars indicate that differences between varieties are significant under same nitrogen condition at 5% level；不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平 Different lowercase letters above the bars indicate that differences of same variety between nitrogen conditions are significant at 5% level.]

的關(guān)鍵酶。由表1可知，兩種供氮水平下，葉片SPS活性品種27號高于品種6號，苗期、抽薹期、開花期呈現(xiàn)相同規(guī)律，兩品種苗期與抽薹期的酶活性差異達(dá)到了顯著水平，開花期差異不顯著；角果發(fā)育初期的角果、角果發(fā)育中期的角果皮和籽粒中的SPS活性也表現(xiàn)為品種27號高于品種6號，角果與籽粒中的酶活性差異達(dá)到了顯著水平。

觀察不同供氮水平對SPS活性的影響，表明兩品種均表現(xiàn)為低氮處理高于正常供氮處理，所有生育期規(guī)律一致，其中品種27號苗期葉片與角果發(fā)育初期角果中的酶活性差異也達(dá)到了顯著水平。與苗期和抽薹期相比，所有處理的開花期葉片的SPS活性明顯下降，說明進(jìn)入生殖生長期以后油菜營養(yǎng)器官的基本干物質(zhì)積累大幅度減弱。

表1　不同氮素供應(yīng)條件下不同油菜品種的SPS活性[mg/(g·h), FW]

注(Note): 數(shù)據(jù)后不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Values followed by different capital letters indicate that differences between varieties are significant under same nitrogen condition at 5% level； 數(shù)據(jù)后不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平Values followed by different lowercase letters indicate that differences of same variety between nitrogen conditions are significant at 5% level.

2.2.2 油菜PEPC活性PEPC可為作物氮代謝提供碳骨架。由表2可以看出，兩種供氮水平下，葉片PEPC活性以品種27號高于品種6號，苗期、抽薹期、開花期呈現(xiàn)相同規(guī)律，其中正常供氮處理下苗期與開花期PEPC活性品種間的差異達(dá)到了顯著水平；無論供氮水平高低，角果發(fā)育初期的角果、角果發(fā)育中期的角果皮與籽粒中的PEPC活性均以品種27號高于品種6號，其中正常供氮處理下的角果和兩種供氮水平下籽粒中的PEPC酶活性兩品種之間差的異也達(dá)到了顯著水平。

表2　不同氮素供應(yīng)條件下不同油菜品種PEPC活性 [μg/(mg·min)]

注(Note): 數(shù)據(jù)后不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Values followed by different capital letters indicate that differences between varieties are significant under same nitrogen condition at 5% level； 數(shù)據(jù)后不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平Values followed by different lowercase letters indicate that differences of same variety between nitrogen conditions are significant at 5% level.

不同供氮水平對PEPC活性的影響顯示，所有生育期兩品種均表現(xiàn)為正常供氮高于低氮處理，除品種27號在角果發(fā)育期的角果和品種6號苗期與抽薹期葉片的PEPC活性差異不顯著之外，其余均達(dá)到了差異顯著水平。

2.3不同氮效率油菜SPS/PEPC比值的差異

SPS/PEPC比值表明單位PEPC活性變化所對應(yīng)的SPS活性變化，可表征碳代謝對氮代謝變化的響應(yīng)情況，由表3可以看出，營養(yǎng)生長期葉片SPS/PEPC在兩種供氮水平下均表現(xiàn)為品種27號高于品種6號，差異顯著；而開花期葉片SPS/PEPC兩品種差異較??；角果發(fā)育期的SPS/PEPC，除正常供氮角果發(fā)育中期角果皮中SPS/PEPC以品種27號高于品種6號之外，其余處理下SPS/PEPC均為品種27號低于品種6號，低氮處理下角果與角果皮、兩種供氮處理下籽粒中的SPS/PEPC值品種間差異達(dá)到顯著水平。說明氮代謝加強(qiáng)時(shí)碳代謝相應(yīng)加強(qiáng)的程度在營養(yǎng)生長期以氮高效品種明顯高于氮低效品種，到開花期則兩品種趨于接近，角果發(fā)育期氮高效品種反而低于氮低效品種。這是因?yàn)榈咝贩N的籽粒油分含量高于氮低效品種，顯然氮高效品種在角果發(fā)育期SPS/PEPC值較低的情況下應(yīng)該另有補(bǔ)充碳素的途徑。供氮水平對SPS/PEPC也有影響，主要表現(xiàn)為低氮條件下的SPS/PEPC值升高。

表3　不同氮水平下兩品種SPS/PEP 比值

注(Note): 數(shù)據(jù)后不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Values followed by different capital letters indicate that differences between varieties are significant under same nitrogen condition at 5% level；數(shù)據(jù)后不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平Values followed by different lowercase letters indicate that differences of same variety between nitrogen conditions are significant at 5% level.

2.4不同氮效率碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率的變化

碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率表示油菜生育前期營養(yǎng)器官所積累的碳素向生殖器官所轉(zhuǎn)運(yùn)的情況。本試驗(yàn)中營養(yǎng)器官累積的碳素以抽薹期最高，因此，本文用抽薹期和收獲期營養(yǎng)器官總碳計(jì)算碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率。圖3表明，收獲期兩種供氮處理下碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率均為品種27號大于品種6號，差異皆達(dá)到了顯著水平，說明品種27號具有更高的碳素轉(zhuǎn)運(yùn)能力；比較不同供氮水平，兩品種皆表現(xiàn)為正常供氮處理下碳素轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率大于低氮處理，差異也達(dá)到了顯著水平。

圖3　不同氮水平下兩油菜品種碳轉(zhuǎn)運(yùn)量與轉(zhuǎn)運(yùn)率Fig.3　Carbon transportation amount and rate of two rape varieties under different nitrogen conditions[注(Note): 柱上不同大寫字母表示同一氮水平不同品種處理間差異達(dá)5%顯著水平Different capital letters above the bars indicate that differences between varieties are significant under same nitrogen condition at 5% level；不同小寫字母表示同一品種不同氮水平處理間差異達(dá)5%顯著水平Different lowercase letters above the bars indicate that differences of same variety between nitrogen conditions are significant at 5% level.]

3　討論

3.1不同氮效率油菜品種SPS與PEPC活性差異及其對籽粒產(chǎn)量與油分含量的影響

碳、氮代謝決定油菜的產(chǎn)量與品質(zhì)，碳代謝與氮代謝競爭光合作用產(chǎn)生的碳架與還原力，而SPS與PEPC在碳、氮代謝交匯點(diǎn)對碳架在碳、氮代謝間的分配及二者代謝方向的調(diào)節(jié)中起重要作用，SPS促進(jìn)碳骨架向碳代謝方向運(yùn)輸，而PEPC促進(jìn)碳骨架運(yùn)往氨基酸形成途徑[16-17]。唐湘如等[18]研究表明，SPS活性高有利于油菜籽粒油分的積累；Rademacher等[19]將PEPC基因轉(zhuǎn)入土豆后發(fā)現(xiàn)，碳素流動直接從糖類與淀粉的合成轉(zhuǎn)入蘋果酸與氨基酸的合成。以上研究已從不同角度證明了SPS與PEPC活性對碳、氮代謝帶來的影響，但是不同氮效率作物品種之間SPS與PEPC活性差異及其對作物產(chǎn)品品質(zhì)影響的研究目前報(bào)道還很少。本試驗(yàn)中氮高效品種的籽粒產(chǎn)量與油分含量高，且葉片及角果的SPS與PEPC活性均高于氮低效品種，即無論是營養(yǎng)生長期還是生殖生長期，氮高效品種均可以向碳代謝與氮代謝輸送更多的碳骨架與能量，氮高效品種的碳(氮)代謝加強(qiáng)，并沒有以抑制氮(碳)代謝為代價(jià)的，這是氮高效品種氮素吸收利用效率高、籽粒累積蛋白質(zhì)多，但并沒有降低籽粒產(chǎn)量與油分含量的物質(zhì)基礎(chǔ)，當(dāng)然其前提是氮高效品種具有更高的光合能力[20]。本試驗(yàn)還表明，供氮水平也影響SPS與PEPC活性，低氮時(shí)，兩個(gè)品種的SPS活性皆升高，PEPC活性皆降低，與唐湘如等[18]和羅鳳等[21]的研究結(jié)果一致。低氮條件下SPS與PEPC活性的以上變化使氮代謝相對減弱，碳代謝相對加強(qiáng)，但是過弱的氮代謝會抑制油菜的正常生長和產(chǎn)量形成，從而導(dǎo)致籽粒油分含量提高、產(chǎn)量卻降低的現(xiàn)象。因此，調(diào)節(jié)碳氮代謝方向，使更多的碳骨架流向碳代謝，必需在保證基本氮代謝的基礎(chǔ)上進(jìn)行，才可達(dá)到既提高產(chǎn)量又提高油分含量的目的。

3.2不同氮效率品種油菜SPS/PEPC差異及其對油菜籽粒產(chǎn)量與油分含量的影響

SPS/PEPC可反映氮代謝加強(qiáng)時(shí)相應(yīng)的碳代謝強(qiáng)化能力，即碳代謝對氮代謝的響應(yīng)能力，該能力強(qiáng)，向碳代謝輸送碳的能力強(qiáng)，反之亦然。已有研究表明，SPS/PEPC降低，更多光合碳化物分配至氨基酸從而增強(qiáng)氮代謝[22]，但以上研究還沒有涉及SPS/PEPC與籽粒品質(zhì)的關(guān)系。本試驗(yàn)計(jì)算的SPS/PEPC結(jié)果表明，營養(yǎng)生長期氮高效品種高于氮低效品種，開花期兩品種相近，角果發(fā)育期氮高效品種反而低于氮低效品種，即碳代謝對氮代謝的響應(yīng)能力，油菜生長前期氮高效品種大于氮低效品種，生長后期則相反，而且上述變化過程基本與生殖生長進(jìn)程相吻合。那么，油菜生長后期氮高效品種累積更多油分的碳素來自何方？鄒娟等[23]指出，油菜苗期是物質(zhì)積累的主要時(shí)期，其決定著籽粒產(chǎn)量的形成，Severine等[24]指出，油菜生育后期籽粒形成所需的干物質(zhì)有很大一部分來自生育前期積累的轉(zhuǎn)運(yùn)，生育前期葉片中蔗糖合成能力決定著后期的產(chǎn)量。本試驗(yàn)用差減法計(jì)算了生育后期營養(yǎng)器官碳素的轉(zhuǎn)運(yùn)量，結(jié)果表明，氮高效品種生育后期由營養(yǎng)器官向籽粒的碳素轉(zhuǎn)運(yùn)量和轉(zhuǎn)運(yùn)率均高于氮低效品種?？梢?，營養(yǎng)生長期氮高效品種不僅向碳、氮代謝輸送的碳骨架多，碳代謝對氮代謝變化的響應(yīng)度也高，而到生殖生長期，營養(yǎng)生長與生殖生長并行，碳、氮代謝之間的矛盾加劇，氮高效品種僅保證向碳、氮代謝輸送更多的碳骨架，碳代謝對氮代謝變化的響應(yīng)度降低，由此不足的碳素由莖葉等營養(yǎng)器官的碳素轉(zhuǎn)運(yùn)來補(bǔ)充，這種方式有利于緩解生殖生長期角果和籽粒中碳、氮代謝對碳骨架的競爭，從而為協(xié)調(diào)籽粒油分與蛋白質(zhì)含量的矛盾并提高產(chǎn)量提供了條件。

4　結(jié)論

1)氮高效油菜品種的籽粒產(chǎn)量與油分含量均高于氮低效品種。

2)氮高效油菜品種的SPS與PEPC活性全生育期皆高于氮低效品種，說明氮高效品種向碳代謝和氮代謝輸送的碳骨架全生育期均多于氮低效品種，這是氮高效品種協(xié)調(diào)籽粒油分與蛋白質(zhì)含量矛盾的重要物質(zhì)基礎(chǔ)。

3)氮高效油菜品種的SPS/PEPC值生育前期較高，生育后期較低，同時(shí)生育后期營養(yǎng)器官有更多的碳素轉(zhuǎn)運(yùn)到籽粒，這為油菜生育后期同時(shí)滿足籽粒碳、氮代謝所需的碳骨架，進(jìn)而為協(xié)調(diào)籽粒油分與蛋白質(zhì)含量的矛盾提供了條件。

4)供氮水平并不改變以上指標(biāo)在品種間的差異，但對上述各指標(biāo)分別產(chǎn)生不同的影響，籽粒產(chǎn)量、PEPC活性、碳素轉(zhuǎn)運(yùn)量及轉(zhuǎn)運(yùn)率以正常供氮高于低氮處理，而油分含量、SPS活性及SPS/PEPC值則為正常供氮低于低氮處理。

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Different activities of SPS and PEPC in oilseed rape with different nitrogen use efficiency and their influence on seed yield and oil-content

YU Jia-ling1, SONG Hai-xing1, XIE Gui-xian1*, ZHANG Zhen-hua1*, LIAO Qiong1, GUAN Chun-yun2

(1CollegeofResourcesandEnvironmentalSciencesofHunanAgriculturalUniversity/NationalEngineeringLaboratoryofSoilandFertilizerResourcesEfficientUtilization/SouthernRegionalCollaborativeInnovationCenterforGrainandOilCropsinChina/HunanProvincialKeyLaboratoryofFarmlandPollutionControlandAgriculturalResourcesUse/HunanProvincialKeyLaboratoryofPlantNutritioninCommonUniversity,Changsha410128,China; 2NationalCenterofOilseedCropsImprovement,HunanBranch,Changsha410128,China)

【Objectives】 Transportation of carbon skeleton into carbon metabolism pathway and nitrogen metabolism circulation were respectively controlled by SPS (sucrose phosphate synthase) and PEPC (phosphoenolpyruvate carboxylase), and then the yield and grain quality of crop were affected by the two enzymes. In order to elucidate the regulation mechanism of contradiction between seed protein and oil during the high nitrogen use efficiency (NUE) progress in oilseed rape with high N efficiency, the different activities of SPS and PEPC and their influence on seed yield and oil content in oilseed rape with different NUE were studied in this paper.【Methods】 Variety No.27 with high NUE (H) and variety No.6 with low NUE (L) were cultured in soil under different nitrogen conditions [normal nitrogen condition(N) and nitrogen stress condition(S)] to study the difference of enzyme activities (SPS and PEPC) in leaf from seedling stage to flowering stage, in silique at early silique stage and in grain and silique husk at silique mid-term stage between the two NUE rape varieties as well as carbon (C) transportation amount and rate and their seed yield and seed oil content. 【Results】The test results showed that seed yield and seed oil content of high NUE (No.27) variety were significantly higher than those of low NUE (No.6) variety under two nitrogen conditions(normal nitrogen and nitrogen stress), the high NUE rape showed obvious variety advantage. Moreover, activities of SPS and PEPC of high NUE (No.27) variety in leaf from seedling stage to flowering stage were higher than those of low NUE (No.6) variety under two nitrogen conditions, the same tendency was found in silique at early silique stage as well as in grain and silique husk at silique mid-term stage. While the SPS/PEPC of the two variety rape was changed at different growth periods, SPS/PEPC of high NUE (No.27) variety in leaf at vegetative stage was higher than those of low NUE (No.6) variety, SPS/PEPC of the two varieties rape was similar in leaf at flowering stage, instead SPS/PEPC in main reproduction organs at silique stage of high NUE (No.27) variety was lower compared to low NUE (No.6) variety, which revealed that amount of delivery of carbon skeleton to C metabolism and N assimilation of high NUE (No.27) variety was more than those of low NUE (No.6) variety during the whole growth period and the response of C metabolism to N assimilation of high NUE (No.27) variety was higher than those of low NUE (No.6) variety at early growth stage, while at late growth stage the response of response of high NUE (No.27) variety was lower than that of low NUE (No.6) variety. Meanwhile C transportation amount and rate of high NUE (No.27) variety were significantly higher than those of low NUE (No.6) variety, which might be the vital physiological mechanism that regulating the contradiction between seed protein and oil during the high nitrogen use efficiency (NUE) progress in oilseed rape with high N efficiency. As for influence of different nitrogen conditions on items which we tested above, the results showed that seed yield, activity of PEPC, carbon transportation amount and rate were higher under normal nitrogen condition than under nitrogen stress condition, but seed oil content, activity of SPS, SPS/PEPC showed an inverse law, these phenomena appeared in the two rape varieties.【Conclusions】Compared to low NUE (No.6) variety, more carbon skeleton was transported into C and N metabolism pathway in high NUE (No.27) variety during the whole growth stage. This was the important premise for HNUE variety to coordinate the contradiction between C and N metabolisms. Response of C metabolism to N assimilation was higher during earlier growth stage than during later growth stage. Meanwhile, higher proportion of C in vegetative organs was transported into seed during later growth stage, which met the demands of carbon skeleton in C and N metabolism and coordinated the contradiction between seed oil and protein contents during later growth stage.

BrassicanapusL.; SPS; PEPC; carbon nitrogen metabolism; seed oil

2014-12-06接受日期： 2015-02-07網(wǎng)絡(luò)出版日期： 2015-12-11

國家自然科學(xué)基金(31372130, 31071851, 31101596); 國家支撐計(jì)劃(2012BAD15BO4, 2010BAD01B01); 湖南省高校創(chuàng)新平臺開放基金(12K064)資助。

余佳玲(1990—)，女，湖南冷水江人，碩士研究生，主要從事植物營養(yǎng)生理研究。E-mail: Haizeiwang00@sina.com

E-mail:xieguixian@126.com; E-mail:zhzh1468@163.com

S565.4.01

A

1008-505X(2016)03-0618-08