葉面噴施亞精胺對鹽堿脅迫下番茄幼苗生長及其葉綠素合成前體含量的影響

張　麗,徐志然,胡曉輝,胡立盼,鄒志榮,潘雄波

(西北農(nóng)林科技大學(xué) 園藝學(xué)院,農(nóng)業(yè)部西北設(shè)施園藝工程重點(diǎn)實(shí)驗(yàn)室,陜西楊陵 712100)

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葉面噴施亞精胺對鹽堿脅迫下番茄幼苗生長及其葉綠素合成前體含量的影響

張麗,徐志然,胡曉輝*,胡立盼,鄒志榮,潘雄波

(西北農(nóng)林科技大學(xué) 園藝學(xué)院,農(nóng)業(yè)部西北設(shè)施園藝工程重點(diǎn)實(shí)驗(yàn)室,陜西楊陵 712100)

摘要:以鹽堿敏感型番茄品種‘中雜9號’幼苗為試驗(yàn)材料,研究葉面噴施0.25 mmol·L-1亞精胺(Spd)對75 mmol·L-1鹽堿溶液脅迫下番茄幼苗生長、凈光合速率及葉綠素合成前體物質(zhì)含量的影響,探討Spd在緩解番茄鹽堿脅迫傷害的生理機(jī)制。結(jié)果顯示:(1)鹽堿脅迫下番茄葉片葉綠素合成前體物質(zhì)原卟啉Ⅸ(Proto Ⅸ)、鎂-原卟啉Ⅸ(Mg-proto Ⅸ)、原葉綠素酸(Pchl)含量均顯著降低,而δ-氨基酮戊酸(ALA)、膽色素原(PBG)、尿卟啉原Ⅲ(Uro Ⅲ)顯著積累,Uro Ⅲ到Proto Ⅸ的轉(zhuǎn)化受阻,引起葉片葉綠素a(Chl a)、葉綠素b(Chl b)和總?cè)~綠素(Chl)含量顯著降低,以及幼苗葉片凈光合速率(Pn)、葉面積、葉片相對含水量、地上和地下部干鮮重的生長指標(biāo)均顯著降低。(2)鹽堿脅迫下,葉面噴施Spd可顯著促進(jìn)番茄幼苗的生長,抑制葉片內(nèi)ALA、PBG、Uro Ⅲ的積累,并提高Proto Ⅸ、Mg-proto Ⅸ、Pchl、Chl a、Chl b、Chl含量和相應(yīng)Pn值。研究表明,鹽堿脅迫顯著抑制番茄幼苗的生長,葉面噴施Spd可通過緩解Uro Ⅲ到Proto Ⅸ的轉(zhuǎn)化受阻程度,促進(jìn)鹽堿脅迫下番茄葉片的葉綠素合成,提高葉綠素含量和凈光合速率,減輕鹽堿脅迫對幼苗生長的傷害。

關(guān)鍵詞:葉面噴施;亞精胺;番茄;鹽堿脅迫;葉綠素合成前體物質(zhì)

隨著人類活動對環(huán)境破壞的加劇,日益嚴(yán)重的全球土壤鹽堿化已成為一個(gè)世界性的環(huán)境、資源和生態(tài)問題,近年來引起了人們的普遍關(guān)注[1]。當(dāng)前,全球鹽堿地面積已達(dá)9.5×108hm2[2],中國的鹽漬土總面積約3.6×107hm2,并且有9.2×107hm2的耕地正在面臨鹽堿化[3],主要分布在西北、華北及東北等地區(qū),嚴(yán)重影響作物的產(chǎn)量、品質(zhì)和效益。土壤鹽堿化是限制植物生長和生產(chǎn)的重要因素,已經(jīng)成為世界灌溉農(nóng)業(yè)可持續(xù)發(fā)展的資源制約因素。

多胺(PAs)是植物體內(nèi)普遍存在的一類具有強(qiáng)烈生物活性的低分子量脂肪族含氮堿,主要包括腐胺(Put)、亞精胺(Spd)和精胺(Spm),PAs通過促進(jìn)生物大分子合成、穩(wěn)定生物膜、清除活性氧自由基、影響跨膜質(zhì)子電化學(xué)梯度及滲透調(diào)節(jié)等作用,參與植物體內(nèi)許多重要的代謝過程及提高植物抗逆性反應(yīng)[4]。近年來,Spd對植物抗鹽性的影響機(jī)理研究日趨深入,但已有研究主要集中在NaCl上[5-6],而對堿性鹽或混合鹽堿逆境的相應(yīng)研究報(bào)道相對較少。本課題組前期研究表明,外源Spd可提高鹽堿脅迫下番茄幼苗的光合作用效率,減輕鹽堿脅迫對番茄幼苗抑制效應(yīng),且對敏感品種的作用效果更為顯著[4],但Spd對番茄等蔬菜葉綠素(Chl)合成調(diào)控的機(jī)理尚不清楚。因此,為進(jìn)一步探討Spd對鹽堿脅迫下影響番茄幼苗葉綠素合成的機(jī)理,本試驗(yàn)以鹽堿敏感的‘中雜9號’番茄為試驗(yàn)材料,采用水培的方式,研究葉面噴施外源Spd對鹽堿脅迫下番茄幼苗生長及葉綠素合成前體物質(zhì)含量的影響,旨在探討Spd在緩解番茄鹽堿脅迫傷害的生理機(jī)制,以期為進(jìn)一步研究和利用Spd提供參考依據(jù)。

1材料和方法

1.1試驗(yàn)材料

試驗(yàn)于2013年4～11月在西北農(nóng)林科技大學(xué)科研溫室中進(jìn)行,以‘中雜9號’(鹽堿敏感型)番茄(Solanumlycopersicum)[4,7]為試驗(yàn)材料。

1.2試驗(yàn)處理

采用穴盤育苗,待番茄幼苗長至三葉一心時(shí),選取長勢一致健壯的幼苗定植于盛有1/2劑量Hoagland營養(yǎng)液的水培槽中預(yù)培養(yǎng),用氣泵通氣。幼苗長至六葉一心時(shí)進(jìn)行不同試驗(yàn)處理。試驗(yàn)共設(shè)4個(gè)處理:(1)對照(CK):1/2劑量Hoagland營養(yǎng)液+葉面噴施蒸餾水;(2)Spd處理(Spd):1/2劑量Hoagland營養(yǎng)液+葉面噴施0.25 mmol·L-1Spd[7];(3)鹽堿處理(MS):75 mmol·L-1鹽堿溶液(NaCl:Na2SO4:NaHCO3:Na2CO3=1:9:9:1)+葉面噴施蒸餾水;(4)鹽堿+Spd處理(MS+Spd):75 mmol·L-1鹽堿溶液+葉面噴施0.25 mmol·L-1Spd。每天18:00～18:30,葉片正反面均勻噴施Spd(噴施前加入2滴Tween-20)或等量的蒸餾水,以葉面產(chǎn)生水膜為止。處理第6天時(shí)選取幼苗生長點(diǎn)下第2片完全展開葉片測定葉綠素含量、凈光合速率、葉綠素合成前體物質(zhì)含量及生長指標(biāo)。每處理48株,4次重復(fù)。

1.3測定指標(biāo)與方法

1.3.1干重、鮮重、葉面積、葉片相對含水量選取各處理10株植株,用蒸餾水沖洗干凈,吸水紙吸干表面水分稱鮮重,再經(jīng)115 ℃殺青15 min,75 ℃烘干至恒重,稱干重;葉面積測定參照高建昌[8]的方法,用臺式掃描儀(EPSON V700)掃描番茄葉片圖像,然后用Image J軟件進(jìn)行葉面積分析;葉片相對含水量參照楊國會等[9]的方法測定。

1.3.2凈光合速率采用Li-6400便攜式光合儀(Li-Cor Inc,USA),上午9:00～11:30對各處理植株生長點(diǎn)下第2片完全展開功能葉的凈光合速率進(jìn)行測定。設(shè)定葉室溫度為26 ℃,照射光強(qiáng)為800 μmol·m-2·s-1,CO2濃度為400 μmol·mol-1。

1.3.3葉綠素和葉綠素合成前體物質(zhì)含量葉綠素含量測定參照張憲政[10]的方法。原卟啉Ⅸ(Proto Ⅸ)、鎂-原卟啉Ⅸ(Mg-Proto Ⅸ)和原葉綠素酸酯(Pchl)含量測定按文獻(xiàn)[11]進(jìn)行;尿卟啉原Ⅲ(Uro Ⅲ)和膽色素原(PBG)含量按Bogorad[12]方法測定;δ-氨基酮戊酸(ALA)含量按文獻(xiàn)[13]進(jìn)行。

1.4數(shù)據(jù)處理和分析

試驗(yàn)數(shù)據(jù)采用Excel 2010繪圖和SAS 8.1軟件進(jìn)行方差分析和Duncan’s多重比較。

2結(jié)果與分析

2.1葉面噴施Spd對鹽堿脅迫下番茄幼苗生長的影響

由表1可知,正常栽培條件下,葉面噴施Spd處理顯著提高了番茄幼苗的葉面積、地上部鮮重、干重和地下部干重;鹽堿脅迫處理顯著抑制番茄幼苗的生長,使番茄的葉面積、葉片相對含水量、地上部鮮重、地下部鮮重、地上部干重、地下部干重分別比對照降低了48.90%、19.89%、58.13%、56.18%、60.92%和37.50%;與單純鹽堿處理相比,鹽堿脅迫下葉面噴施Spd處理的番茄幼苗的葉面積、相對含水量、地上部鮮重和干重、地下部鮮重和干重分別增加了20.33%、10.27%、28.21%、30%、44.07%和20%,且除地下部干重外,其余各指標(biāo)均達(dá)到顯著水平。表明葉面噴施Spd可有效緩解鹽堿脅迫對“中雜9號”番茄幼苗生長的抑制作用。

2.2葉面噴施Spd對鹽堿脅迫下番茄葉綠素含量的影響

表2顯示,正常栽培條件下,葉面噴施Spd使番茄葉片總?cè)~綠素和葉綠素a含量分別顯著提高7.95%和8.56%,但對葉綠素b無明顯提高;在處理第6天時(shí),單純鹽堿處理的番茄葉片總?cè)~綠素、葉綠素a、葉綠素b含量均比對照顯著降低;與單純鹽堿脅迫相比,鹽堿脅迫下葉面噴施Spd顯著提高了番茄總?cè)~綠素、葉綠素a、葉綠素b含量。表明葉面噴施Spd能有效降低鹽堿脅迫對幼苗葉綠素的破壞作用,并且對葉綠素b的作用效果更顯著。

2.3葉面噴施Spd對鹽堿脅迫下番茄幼苗葉片葉綠素合成前體物質(zhì)含量的影響

2.3.1ALA、PBG、Uro Ⅲ含量由圖1可知,正常栽培下,葉面噴施Spd對番茄幼苗葉片葉綠素合成前體物質(zhì)ALA和Uro Ⅲ含量無顯著影響,而使PBG含量有所降低;鹽堿脅迫下番茄葉片ALA、PBG、Uro Ⅲ含量較對照均有大幅度顯著增加,增幅分別達(dá)47.05%、110.07%和150.42%;鹽堿脅迫下噴施Spd顯著降低了單純鹽堿脅迫引起的ALA、PBG、Uro Ⅲ累積,但仍顯著高于對照。說明番茄幼苗葉片ALA、PBG、UroⅢ含量在鹽脅迫逆境下顯著增加,而噴施Spd能有效降低它們的積累量。

2.3.2Proto Ⅸ、Mg-proto Ⅸ、Pchl含量圖1還顯示,正常栽培條件下,葉面噴施Spd對番茄幼苗葉片葉綠素合成前體物質(zhì)Proto Ⅸ、Mg-proto Ⅸ、Pchl含量也無顯著影響;與對照處理相比,鹽堿脅迫下番茄葉片的Proto Ⅸ、Mg-proto Ⅸ、Pchl含量顯著降低,表明鹽堿脅迫減弱了Proto Ⅸ、Mg-proto Ⅸ、Pchl的合成能力;與單純鹽堿脅迫相比,鹽堿脅迫下葉面噴施Spd能顯著提高Proto Ⅸ、Mg-protoⅨ和Pchl含量,增幅分別為11.31%、12.29%和12.64%,且達(dá)到與對照接近的水平,表明Spd能有效促進(jìn)鹽堿脅迫下番茄葉片葉綠素的合成。

2.4葉面噴施Spd對鹽堿脅迫下番茄葉片凈光合速率的影響

從圖2可知,正常栽培條件下,葉面噴施Spd對番茄葉片的凈光合速率Pn無顯著影響;鹽堿脅迫顯著抑制了幼苗光合作用,番茄葉片Pn比對照顯著降低了56.81%;同時(shí),鹽堿脅迫下葉面噴施Spd能顯著提高番茄Pn,與單純鹽堿脅迫處理相比顯著提高了43.37%,但仍低于對照水平。這表明鹽堿脅迫下外源Spd可顯著提高‘中雜9號’番茄幼苗的凈光合速率,在一定程度上緩解鹽堿脅迫對幼苗光合作用的抑制。

表2　葉面噴施Spd對鹽堿脅迫下番茄葉綠素含量的影響

表1　葉面噴施Spd對鹽堿脅迫下番茄幼苗生長的影響

注:CK.對照(1/2 Hoagland);Spd.葉面噴施亞精胺;MS.鹽堿脅迫;MS+Spd.鹽堿脅迫后葉面噴施亞精胺;表中同列不同字母表示處理間在0.05水平差異顯著;數(shù)值為平均值±SE;下同。

Note:CK.Control(1/2 Hoagland);Spd.Foliar-spraying spermidine;MS.Saline-alkaline stress;MS+Spd.Foliar-spraying spermidine after saline-alkaline stress;Different letters in the same column meant significant difference among treatments at 0.05 level;Values were means±SE;The same as below.

圖1　葉面噴施Spd對鹽堿脅迫下番茄幼苗葉片葉綠素合成前體物質(zhì)含量的影響

圖2　葉面噴施Spd對鹽堿脅迫下番茄

3討論

生物量變化是植物對鹽堿脅迫的綜合反應(yīng),是評估脅迫程度和植物抗鹽能力的可靠指標(biāo)[14]。本研究表明番茄各項(xiàng)生長指標(biāo)在鹽堿處理6 d時(shí)均降低,其中番茄植株干重尤為顯著;鹽堿脅迫下,葉面噴施Spd處理能夠顯著改善番茄幼苗地上部的生長狀況,緩解鹽堿脅迫對地上部生物量積累的抑制作用,但對植株地下部生長的促進(jìn)效應(yīng)并不明顯。

葉片光合色素含量是反映植物光合能力的一個(gè)重要指標(biāo),環(huán)境因子的改變會引起葉綠體色素含量的變化,進(jìn)而引起光合性能的改變[15]。本研究結(jié)果表明,鹽堿脅迫后,番茄幼苗葉片葉綠素含量顯著降低,而葉面噴施Spd可以顯著提高番茄幼苗的葉綠素含量,且對葉綠素b含量影響更為明顯,可能是因?yàn)镾pd處理后,一部分葉綠素a先與反應(yīng)中心蛋白結(jié)合形成特殊狀態(tài)下的葉綠素a,達(dá)到飽和后剩余的葉綠素a在脫植基葉綠素a加氧酶的作用下經(jīng)過兩步氧化反應(yīng)最終生成葉綠素b,這與DA-6處理桃樹葉片的結(jié)果一致[16]。本研究中鹽堿脅迫下番茄葉綠素含量的高低與凈光合速率高低變化趨勢相一致,說明葉綠素含量的變化可影響凈光合速率的變化,這與華春等[17]的研究結(jié)果相一致。Spd可通過參與膜構(gòu)成阻止膜脂過氧化及膜蛋白的水解作用、穩(wěn)定類囊體膜組成、阻止葉綠素?fù)p失[18],進(jìn)而顯著提高鹽堿脅迫下番茄幼苗的凈光合速率。

葉綠素的生物合成主要通過以下途徑:谷氨酸(Glu)→δ-氨基酮戊酸(ALA)→膽色素原(PBG)→尿卟啉原Ⅲ(Uro Ⅲ)→原卟啉Ⅸ(Proto Ⅸ)→鎂-原卟啉Ⅸ(Mg-proto Ⅸ)→原葉綠素酸(Pchl)→葉綠素a(Chl a)→葉綠素b(Chl b),Mg-proto Ⅸ形成之前的合成過程均在葉綠體基質(zhì)進(jìn)行,而后發(fā)生在類囊體膜上[13]。其中,任何一步出現(xiàn)障礙都會導(dǎo)致受阻礙部位以前的中間產(chǎn)物顯著積累,受阻位點(diǎn)之后的產(chǎn)物則顯著降低[19]。本試驗(yàn)結(jié)果表明,鹽堿脅迫下葉綠素合成前體物質(zhì)ALA、PBG、UroⅢ大量積累,而Proto Ⅸ、Mg-proto Ⅸ、Pchl含量顯著降低,說明鹽堿脅迫造成番茄葉綠素合成受阻發(fā)生在Uro Ⅲ向Proto Ⅸ的轉(zhuǎn)化,這與郝樹芹等[20]關(guān)于西葫蘆銀葉病發(fā)病葉片葉綠素合成受阻位點(diǎn)的研究結(jié)果相一致,發(fā)生此變化的原因可能與類囊體膜受損有關(guān)。葉綠素合成途徑的很多酶屬脂溶性,與葉綠體類囊體膜的發(fā)育密切相關(guān)[21]。多胺作為多聚陽離子,生理pH條件下帶正電荷可與帶電荷的磷酸基團(tuán)、蛋白質(zhì)及核酸等相互作用,穩(wěn)定類囊體組成并參與膜構(gòu)建[22]。本試驗(yàn)中,鹽堿脅迫下,葉面噴施Spd降低了Uro Ⅲ的積累,促進(jìn)了Proto Ⅸ向葉綠素的合成,提高了凈光合速率,有效緩解鹽堿脅迫對Uro Ⅲ到Proto Ⅸ轉(zhuǎn)化的阻礙作用,這可能是Spd有助于穩(wěn)定逆境脅迫下葉綠體類囊體膜的發(fā)育[23],從而保證了葉綠素合成由Uro Ⅲ到Proto Ⅸ轉(zhuǎn)化過程中有充足的酶參與催化,促進(jìn)了葉綠素的合成。但Spd對鹽堿脅迫下番茄幼苗葉綠體結(jié)構(gòu)以及合成關(guān)鍵酶的影響仍需要進(jìn)一步深入研究。

綜上所述,鹽堿脅迫阻礙番茄幼苗葉片葉綠素合成中間產(chǎn)物Uro Ⅲ到Proto Ⅸ的轉(zhuǎn)化,影響葉綠素的合成,造成葉綠素含量降低,進(jìn)而降低其凈光合速率,抑制植株生長。葉面噴施Spd能有效緩解鹽堿脅迫下葉綠素合成步驟中Uro Ⅲ向Proto Ⅸ的受阻程度,促進(jìn)其合成轉(zhuǎn)化,提高葉綠素含量。

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(編輯:裴阿衛(wèi))

Introduction of the Plant Front Cover:PetrocosmeaqinlingensisW.T.Wang

PetrocosmeaqinlingensisW.T.Wang belongs to the Family Gesneriaceae.Among all the species ofPetrocosmea,P.qinlingensisis on the northest edge of the distribution area of the genus.It is a perennial herbaceous plant with 7-12 leaves on each individual.Petioles short or long.Leaf blade papyraceous,wide ovate,rhombic or nearly rotund,0.7-3 cm in length,0.7-2.8 cm in width.Apex rotund or truncate.Basal part cuneate.Margin repand or unobvious creanate.Pubrulent on both side.Inflorecence 2-6.1 flower on each inflorescence.Calyx 5 lobed.Pubescent on absixal surface.Corolla labiate,light purple.Sparsely pubescent on out surface.Pilose on inner surface.Corolla tube about 2.8mm.Upper lobe 4.8mm in length and 2 divided.Lower lobes almost the same length as the upper ones,3 divided.Lobes oblong.Apex rotund.Fertile stamens 2,nearly basal.Pistil about 5mm long.Ovary and style villous.Stigma small and spherical.Flowering period August to September.The nearly related species,P.sinensisOliv.,is differed fromP.qinlingensisin having smooth inner surface of corolla.

The species was first descripted by the famous taxonomist,Wang Wencai,in 1981.The type specimen was collected from Mianxian County,Shaanxi Province.In the following 30 years,people tried to look for the wild population of the species but failed.Until recently,when carrying out the program ‘Second Investigation of wild plant resources in Shaanxi Province’,P.qinlingensiswas rediscovered near the location where it has been first found.

P.qinlingensisis an endemic species in Qinling Mountains area.It is usually found on moist rock in deciduous forest valley.The plant is a rare species and its distribution area is very small.It has been listed in the first group of national endangered wild plant species (class Ⅱ).

(Photographed and introduced by WANG Yong,YANG Peijun,LI Changbo and FAN Rong)

Effect of Foliar-spraying Spermidine on Seedlings Growth and

Contents of Chlorophyll Biosynthesis Precursors in

Leaves of Tomato under Saline-alkaline Stress

ZHANG Li,XU Zhiran,HU Xiaohui*,HU Lipan,ZOU Zhirong,PAN Xiongbo

(College of Horticulture,Northwest A&F University,Key Laboratory of Horticultural Engineering in Northwest China,Ministry of Agriculture,Yangling,Shaanxi 712100,China)

Abstract:With the salinity-alkalinity-sensitive tomato cultivar ‘Zhongza No.9’ as the experimental material,the effects of foliar-spraying Spd (0.25 mmol·L-1) on the growth paramaters,the net photosynthetic rate (Pn) and contents of chlorophyll biosynthesis precursors in tomato seedlings grown hydroponically under 75 mmol·L-1mixed saline-alkaline solution were studied.The results showed that:(1)Under saline-alkaline stress,the contents of chlorophyll biosynthesis precursors-protoporphyrin Ⅸ(Proto Ⅸ),Mg-Protoporphyrin Ⅸ(Mg-Proto Ⅸ),protochlorophyll (Pchl) were significantly decreased,while the contents of δ-aminolevulinic acid (ALA),porphobilinogen(PBG),uroorphyrinogen Ⅲ(Uro Ⅲ) were significantly accumulated in leaves of tomato seedlings.It was showed that stress restrained the transformation obstruction from Uro Ⅲ to Proto Ⅸ and lead to decrease in contents of Chl a,Chl b and total Chl,and reduced thePn,leaf area,leaf relative water content,fresh and dry weight of shoot and root.(2)Under saline-alkaline stress,foliar-spraying Spd could effectively promote tomato seedlings growth and suppress the accumulation of ALA,PBG,URO Ⅲ and also increase contents of Proto Ⅸ,Mg-proto Ⅸ and Pchl,and enhance thePnvalue.These results indicated that exogenous Spd could significantly relieve the degree of transformation obstruction from Uro Ⅲ to Proto Ⅸ,promote the tomato leaf chlorophyll synthesis and increase the chlorophyll content and net photosynthetic rate and also alleviate the stress damage under saline-alkaline stress.

Key words:foliar-spraying;spermidine;tomato;saline-alkaline stress;chlorophyll synthesis precursor

中圖分類號:Q945.78

文獻(xiàn)標(biāo)志碼:A

作者簡介:張麗(1989-),女,在讀碩士研究生,主要從事設(shè)施園藝研究。E-mail:precious0028@126.com*通信作者:胡曉輝,博士,副教授,主要從事設(shè)施園藝研究。E-mail:hxh1977@163.com

基金項(xiàng)目:國家“十二五”科技支撐計(jì)劃(2011BAD29B01);國家星火計(jì)劃(2012GA850001);西北農(nóng)林科技大學(xué)?；?QN2013018)

收稿日期:2014-07-02;修改稿收到日期:2014-10-06

文章編號:1000-4025(2015)01-0125-06

doi:10.7606/j.issn.1000-4025.2015.01.0125