APP下载

氮素与豆科作物固氮关系研究进展

2017-03-16夏玄龚振平

东北农业大学学报 2017年1期
关键词:结瘤根瘤固氮

夏玄,龚振平

(东北农业大学农学院,哈尔滨 150030)

氮素与豆科作物固氮关系研究进展

夏玄,龚振平

(东北农业大学农学院,哈尔滨 150030)

氮素与根瘤固氮结合可达高产,两者矛盾对根瘤固氮产生不利影响。氮素影响根瘤固氮作用机制仍不明确。文章在现有研究成果基础上,总结氮素与大豆根瘤固氮关系研究发展进程;综述不同氮素形态和氮素浓度对根瘤形成和生长、根瘤固氮酶活性影响及相关机制研究动态;阐述氮素抑制根瘤固氮碳水化合物争夺、抑制根瘤氧供给、硝酸盐毒害、反馈调节及其他可能抑制机制;提出氮素抑制结瘤氮浓度界限模糊化,不同氮素形式、豆科种类氮素抑制机制差异化及详细抑制机制不明确等问题。

氮素;根瘤;抑制;机制

豆科作物与根瘤菌通过复杂相互作用,形成豆科作物独特高效生物固氮体系。但豆科作物尤其是大豆,单纯依靠根瘤固氮无法达到高产目标。氮肥施入尤为重要。氮素与根瘤固氮存在正负相关并存的复杂关系。土壤中某种盐类阻碍根瘤正常生长,如硝酸盐类[1]。探索氮素与根瘤固氮关系可提高共生固氮能力,优化作物管理措施,克服化合态氮对根瘤固氮不利影响,促使两者可持续协调发展。目前氮素影响根瘤作用机制仍无明确结论,国外取得成果较多,国内发展相对滞后。本文总结氮素与大豆根瘤固氮关系成果,旨在探究两者作用机制提供理论基础。

1 氮素对大豆根瘤固氮影响

1.1 氮素对大豆根瘤形成和生长影响

1.1.1 氮素形态对根瘤形成和生长影响

氮素形态主要为硝态氮、铵态氮和尿素。刘莉等对不同品种大豆接种根瘤菌与根毛侵染试验研究认为,高浓度化合态氮通过早期阻碍根瘤菌对根毛侵染而抑制根瘤菌与大豆共生关系建立,抑制影响程度排序为:(NH4)2SO4>NH4NO3>KNO3,抑制结瘤作用NO3-浓度高于NH4+浓度[2]。Guo等以尿素、硝酸盐、铵盐及硝酸铵为氮源,在两种浓度(5和10 mmol·L-1)下研究氮素对蚕豆(Fababean)、白羽扇豆(White lupin)、苜蓿根瘤形成、生长、固氮酶活性影响,高浓度较低浓度抑制效果更明显,而NH4Cl抑制根瘤最严重,5 mmol·L-1浓度尿素抑制根瘤效果最轻[3]。严君等施用不同形态氮肥研究表明,不同形态氮源对根瘤干重、数量有促进作用,增加根瘤中含氮量和氮积累量,根瘤干重及数量变化表现为铵态氮>蛋白氮(豆粉)>硝态氮>氨基酸态氮(甘氨酸)>酰胺态氮(尿素)>不施氮肥[4]。Gan等研究认为,在低浓度下与硝酸铵、硝态氮相比,单独施用铵态氮使大豆具有更高生物积累量、根瘤干重、总氮积累量[5]。董守坤等采用15N标记法以硫酸铵为氮源研究表明,随氮浓度增加,根瘤干重呈先升后降变化趋势,当营养液氮浓度为3.57 mmol·L-1(50 mg·L-1)时,有利于根瘤生长[6]。宋海星等研究表明,铵态氮较硝态氮有利于大豆生长,前者对根瘤固氮抑制作用明显低于后者[7]。Svenning等利用水培法研究氮素对白三叶草结瘤影响认为,NH4+与NO3-在20 mmol·L-1浓度恒定不变条件下,以NH4+为氮源处理较以NO3-为氮源处理固氮量大[8]。Rys和Phung以NH4Cl、Na-NO3和NH4NO3为氮源研究表明,NH4NO3对三叶草根瘤重量、固氮酶活性影响抑制最严重,而NH4+降低溶液pH,未对根瘤数量、重量和固氮酶活性及植株生长产生较大影响[9]。Wahab和Abd-Alla对两种大豆Clark和Crauford作KNO3和NH4Cl不同施氮量试验(0、16、32、64、128 kg N·hm-2),在较低施氮水平下两个大豆品种生长和结瘤均明显增加,NH4+更适合作为临时氮源提高根瘤数量和重量[10]。Gulden和Vessey研究认为,低浓度NH4+促进豌豆根瘤形成及生长,一旦将NH4+移除,相关植株生长率,结瘤数量、重量及固氮酶活性均与未施加NH4+处理相似[11]。Imsande将大豆经不同浓度NO3-和NH4+连续培养,相同浓度下NO3-抑制根瘤重量及固氮酶活性程度均高于NH4+,试验控制pH,说明NH4+抑制结瘤并非酸毒害结果[12]。

由氮素形态对结瘤抑制试验可见,不同形态氮对结瘤和固氮酶活性抑制效果不同,硝态氮对根瘤生长发育及固氮酶活性抑制作用较铵态氮更严重。暗示硝态氮、铵态氮抑制大豆根瘤形成至少有两种机制作用。以往研究中NO3-对结瘤和固氮影响研究较多,对NH4+研究相对较少[13-14],两者对豆类作物结瘤固氮影响差异性比较研究较少[15-16]。

1.1.2 氮素浓度对根瘤形成和生长影响

氮素抑制结瘤固氮浓度问题是研究热点,尤其是较高浓度氮对结瘤及根瘤固氮抑制作用。

Daimon等研究指出,氮浓度在14 mmol·L-1以上,根瘤数量和重量均受到显著抑制[17]。Guo等指出,5和10 mmol·L-1硝酸盐、铵盐混合物和尿素均抑制豆科作物根瘤生长,浓度越高抑制效果越明显[3]。Gan等研究表明,10 mmol·L-1氮浓度无论是硝态氮、铵态氮还是硝酸铵,均显著降低大豆根瘤数量、根瘤重量以及总固氮量[5]。Macduff等通过0、10、100和1 000 mmol·L-1不同浓度NO3-对固氮抑制试验表明,随NO3-浓度增加固氮抑制越严重,即使在提供最低氮浓度10 mmol·L-1水平下,增加NO3-固氮无提高[18]。Carroll等认为在5.5和5 mmol·L-1氮浓度条件下,大豆根生长及结瘤受到抑制[19-20]。Serraj等提出3 mmol·L-1KNO3可完全抑制大豆结瘤[21]。较高浓度氮抑制结瘤及固氮,低浓度氮促进或降低结瘤及固氮研究已有报道。Gulden和Vessey通过砂培试验报道,铵盐在大豆结瘤过程起负面影响,但与0和2 mmol·L-1铵盐处理相比,0.5和1 mmol·L-1铵盐使大豆植株结瘤和固氮效果更佳[13]。Daimon等利用溶液培养试验发现,3.5和7 mmol·L-1对根瘤形成起促进作用,而在0.7 mmol·L-1下根瘤数量下降,但根瘤鲜重提高[17]。通过溶液培养大豆植株结瘤在4 mmol·L-1KNO3和2 mmol·L-1(NH4)2SO4中受抑制,其中4 mmol·L-1KNO3根瘤干重显著受抑制,显著抑制早晚两阶段根瘤发展[12]。张荣铣等在水培条件下研究不同NO3-浓度对大豆结瘤固氮影响发现,0.71 mmol·L-1(10 mg·kg-1)NO3-使根瘤干重增加43%;而≥2.14 mmol·L-1(30 mg·kg-1)时,根瘤干重受抑制[22]。Gan等将大于5 mmol·L-1氮设为高浓度氮,认为1和3.75 mmol·L-1为低浓度氮,试验表明低浓度氮显著提高大豆根瘤数量、根瘤重量及每株大豆总固氮量[5]。Streeter等指出大豆适于生长在复合氮量较小环境中,建议砂培培养氮浓度为1~2 mmol·L-1[23]。Gibson和Harper提出,当NO3-浓度1 mmol·L-1时,大豆根瘤形成及根瘤固氮酶活性均受到延缓和阻碍[24]。

1.2 氮素对大豆根瘤固氮影响的局部性和系统性

1.2.1 氮素对根瘤固氮酶活性影响

根瘤固氮酶是衡量根瘤固氮活性重要指标。乙炔还原法推进了氮与抑制根瘤关系研究。Minchin等认为乙炔还原法存在误导结果问题,对多种处理比较无效[25]。但Schuller等指出,利用乙炔还原法和15N标记法研究硝酸盐对大豆根瘤固氮影响结果一致[26]。乙炔还原法测定根瘤固氮酶活性已广泛应用,但氮素抑制固氮酶活性机制仍不明确。

研究指出,在硝酸盐存在条件下,固氮效率明显降低[27-29]。Streeter利用砂培供给大豆15 mmol·L-1硝态氮7 d,在供氮1 d后固氮酶活性受抑制,与对照相比,随时间推移固氮酶活性抑制程度达80%[30]。Skrdleta等用珍珠岩培养豌豆,供给20 mmol·L-1硝态氮处理,固氮酶活性同样在1 d受显著抑制,而根瘤生长(根瘤干重)则在开始处理后3 d受抑制[31]。硝酸盐施入豆科作物生长介质后,通过NO3-还原酶还原成NO2-,NO2-直接抑制固氮酶活性[32],或形成NO混合物阻碍固氮进程[33]。

1.2.2 氮素对大豆根瘤形成和固氮酶活性影响的局部性与系统性

Hinson利用土壤盆栽,将大豆根系分为两份,其中一侧大豆根系施氮,抑制另一侧不施氮根瘤重量,但并未抑制根瘤数量[34]。Carroll和Gresshoff利用相似方法研究硝酸盐对白三叶草结瘤及固氮影响,根部直接施氮产生局部性抑制根瘤形成现象[35]。Silsbury等供给小型草地三叶草(Small swards of subterranean clover)1和5 mmol·L-1NO3-与0 mmol·L-1对照相比,三叶草固氮酶活性明显降低,而植株和根部NO3-含量明显增加,不能证明NO3-对固氮酶活性影响是NO2-积累而致毒害作用;利用盆栽分根法,将三叶草根平分成两部分,一侧根供给15 mmol·L-1NO3-,与两侧均不施氮处理相比,施氮侧根瘤固氮酶活性在处理2 d后迅速降低,而与施氮侧对应的不施氮侧固氮酶活性降低,仅滞后2 d。试验结果认为,固氮和硝酸还原补充整株植株降低氮素,而NO3-抑制固氮通过系统性调节[36]。研究指出根瘤发展及固氮酶活性由系统性生理控制[37]。Kohls等报道,根毛受抑制导致根瘤产生受抑制,而硝酸盐对根毛抑制局部影响,推断硝酸盐抑制结瘤形成局部影响[38]。Arnone等通过分根法研究表明,硝酸盐抑制根瘤形成和发育是局部性的,抑制固氮酶活性则是系统性的[39]。Tanaka等在水培条件下利用分根法将大豆根平分成两部分,一侧大豆根供给浓度为0、2.14、7.14、14.28 mmol·L-1硝态氮,随施氮浓度增加,大豆根生长和吸收硝态氮速率增加,但根瘤干重和固氮酶活性受阻,显著降低;当氮浓度在7.14 mmol· L-1以下时,对应不施氮根的根瘤干重和固氮酶活性并未受到显著影响甚至起促进作用;当施氮根一侧氮浓度在14.28 mmol·L-1时,不施氮一侧根瘤干重和固氮酶活性受不利影响[40]。Daimon等利用盆栽分根法对花生一侧根施用14 mmol·L-1硝态氮处理,施用硝态氮5 d后,在一侧根施氮不影响不施氮一侧根瘤数量和重量,但施氮侧根瘤固氮酶活性明显低于另一侧;在施氮处理30 d后,硝态氮抑制同时影响施氮及不施氮组。因此,认为植株供氮30 d后,硝态氮对根瘤固氮酶活性抑制影响是系统性的;而短期供氮5 d后对根瘤固氮酶活性抑制则是非系统性的[41]。

2 氮素抑制根瘤固氮机制

氮素抑制结瘤固氮试验,多集中于硝酸盐,因供给土壤各种形态氮多数会通过挥发淋湿消化作用迅速转化成硝酸盐[42]。

较高浓度硝酸盐如何抑制根瘤固氮具体原因与机制仍不明确,但研究表明硝酸盐对根瘤菌侵染、根瘤形成和发展及根瘤固氮酶活性等各阶段均有消极影响,各过程作用机制不同,机理研究见表1。

表1 氮素抑制根瘤固氮机理Table 1Inhibition mechanism of nitrogen on nodule nitrogen fixation

2.1 碳水化合物争夺机制

Orcutt和Wilson发现高浓度硝酸盐可降低大豆叶、茎、根中还原糖和蔗糖含量[43]。Stephens等在离体大豆根瘤、Houwaard在完整豌豆植株中发现,蔗糖可缓解硝酸盐抑制根瘤固氮酶活性[44-45]。Wong研究表明,葡萄糖、蔗糖、果糖缓解硝酸盐抑制扁豆根瘤固氮酶活性[46]。Small等利用14C标记研究认为,豆科作物吸收同化氮素时,消耗碳水化合物,供给根部及根瘤碳水化合物减少[47-48]。Bacanamwo和Harper研究认为,NO3-抑制大豆固氮酶活性程度与植株组织中N和C浓度水平有关,与根瘤中可利用碳水化合物及根瘤中碳氮比呈正相关[49]。然而,Singleton和Van利用密闭分根系统将根平分为两部分,对两侧根作施氮和不施氮处理,分别通空气和Ar(氩气)与O2混合气(Ar 80%,O220%),研究发现,施氮一侧根与不施氮一侧根相比可接受主要光合产物碳水化合物,与光合产物争夺假设相反[50]。综上所述,碳水化合物机制研究仍存疑点。

2.2 抑制根瘤氧供给机制

Minchin等利用流入式系统(Flow-through),供给白三叶草(Trifolium repens)20 mmol·L-1NO3-发现,根瘤固氮酶活性降低同时伴随O2扩散障碍增加[51]。Carroll等分别供给大豆7.5和10 mol·L-1浓度KNO3使其产生高氮胁迫,在供O2浓度由21%提升到60%时,根瘤固氮酶活性提高。硝酸盐使根瘤中O2供给受阻碍而抑制根瘤活性[52]。Minchin等分别供给菜豆和豇豆10 mmol·L-1NO3-,处理3 d,利用流入式系统调节O2供给浓度,随O2浓度增加,两种豆类作物根瘤固氮酶活性呈增加趋势,两种豆类根瘤菌和细胞液中均含有硝酸还原酶,在处理期间硝酸还原酶活性提升1.5~2倍,硝酸还原酶活性随处理时间推移而上升。因此,认为NO3-抑制根瘤固氮分为两个步骤:①提升O2扩散阻碍,②NO3-进入菌类区域从新陈代谢上产生抑制和破坏[53]。Arrese-Igor等对紫花苜蓿研究支持该观点,但均缺乏O2扩散阻碍直接测定[54-55]。

2.3 硝酸盐毒害机制

硝酸盐对根毛形成有毒害性。Munns和Wahab等分别利用紫花苜蓿和豌豆、蚕豆、豇豆、菜豆为试验材料,施加硝态氮后对根毛侵染和卷曲度研究发现,硝态氮抑制根毛形成及根瘤菌侵染,影响结瘤数量[56-57]。积累的硝态氮可在转化成亚硝态或NO后是必需元素,也可作为某种分子信号发挥调节作用[58-59],影响结瘤和固氮。Becana和Wasfi等通过研究不同氮浓度与根瘤硝酸还原酶关系认为,硝酸盐抑制根瘤固氮酶活性可能与NO2-在根瘤中积累产生毒害机制有关[60-61]。Nelson利用硝酸还原酶缺乏的豌豆突变品种研究认为,NO3-在根瘤中同化积累并未直接参与根瘤固氮酶活性抑制过程[62]。Chen等研究化合态氮对根瘤衰老影响也认为,硝酸盐并未通过硝酸还原酶与固氮酶竞争光合产物而诱导根部根瘤衰老[63]。目前,亚硝酸盐毒害机制相比其他机制无更强说服力。

2.4 反馈调节机制

根瘤形成由反馈调节系统性控制(Autoregulation of nodulation),即反馈机制AON,其调控信号有诸多观点[64-66]。Caetano-Anollés等认为AON调节开始由根部皮层细胞分裂诱导产生某种信号,该信号或通过木质部液传输至植株地上部,经地上部诱导相关消极调节反应,最终根瘤发展进一步受阻,反馈抑制在控制根瘤数量方面是系统性反应[67-68]。Ito等通过显微镜观察叶片细胞发现,超结瘤大豆NOD1-3和NOD3-7与野生型大豆相比,叶片细胞数量和叶面积均显著小于后者,但叶细胞面积间无显著差异,因此认为叶片细胞数量少导致超结瘤大豆NOD1-3和NOD3-7叶面积小。Ito发现野生型大豆接种根瘤菌处理的叶片(最初完全展开叶片)细胞数量和细胞面积均显著大于不接种根瘤菌处理,提出AON调节信号或许与叶片增殖细胞控制系统有关假设,认为结瘤野生类型大豆AON机制可促进叶片数量增加[69]。Neo等研究羽扇豆(Lupinus albus)结瘤韧皮部谷氨酰胺指出,结瘤反馈机制通过硝酸盐作用机制中产物(如谷氨酰胺)产生影响[70]。Searle等证明大豆AON被受体激酶GmNARK(Glycine max nodule autoregulation receptor kinase)调节,而这种受体激酶与拟南芥CLAVATA1(CLV1)调节类似,CLV1通过茎尖短距离信号控制茎细胞增殖在蛋白质复合体中发挥作用,叶片中GmNARK表达在长距离与根瘤及次生根沟通中有重要作用[71]。Wang等则通过不同浓度硝酸盐处理,分析拟南芥硝酸盐诱导基因,认为积累硝态氮NO3-及NO2-可能作为某种分子信号在植株生长发育过程中产生调节[58]。Reid等通过5、10 mmol·L-1硝酸盐诱导条件下,正常大豆与超结瘤大豆互相嫁接,认为根部NARK(受体激酶)可能局部调节结瘤,而NARK(受体激酶)是进一步触发地上部抑制产物和抑制根瘤发展的信号产物[72]。

Francisco等通过Enrei与其突变体En6500地上部与根部相互嫁接,以Enrei为地上部,以En6500为地下部,En6500超结瘤和硝酸盐耐受特性均被废除,相反,以En6500为地上部,以Enrei为地下部,En6500具有超结瘤性且对硝酸盐耐受性重新恢复。根瘤可自动调节,硝酸抑制结瘤由地上部分控制,在根瘤形成前即产生阻碍[73]。某些大豆品种超结瘤突变体结瘤对硝酸盐忍耐性极强,在较高硝酸盐浓度下仍表现较高数量结瘤,这可能因AON调节机制缺乏,AON由地上部分系统控制而非根部[74-76]。Day等通过11种超结瘤大豆与结瘤正常Bragg品种地上部与地下部分相互嫁接,研究供给7.5 mmol·L-1KNO3和不供给条件下根瘤数量。发现7.5 mmol·L-1KNO3浓度下,以超结瘤为嫁接的地上部分,无论地下部分是哪个品系,根瘤数量仍表现超结瘤数量,对氮素不敏感;而以正常结瘤品系Bragg为嫁接地上部分,以超结瘤为嫁接地下部分则表现根瘤数量受7.5 mmol·L-1KNO3强烈抑制。硝酸盐对大豆根瘤形成和发展影响依靠硝酸盐和自动反馈调节信号相互作用。在超结瘤突变体中自动反馈调节信号改变或缺失,致使突变体对硝酸盐不敏感[77]。Hamaguchi等通过大豆野生品种与对氮素具有耐受性大豆超结瘤品种在不同氮浓度条件下作地上和地下部分嫁接,认为超结瘤大豆对氮素忍耐性及结瘤由地上部分控制,由地下部分调节缓冲。以结瘤大豆与不结瘤大豆相互嫁接试验得出不同结果[78]。Delves等利用不结瘤品种nod49分别与结瘤正常品系Bragg及超结瘤品系nts382作地上和地下部分嫁接试验,结果表明以不结瘤品系nod49为嫁接地下部分,以Bragg或者nts382为嫁接地上部分,根瘤数量皆为0;而以nod49为嫁接地上部分,Bragg为嫁接地下部分,根瘤数量与Bragg相差不多略有减少,以超结瘤品系nts382为嫁接地下部分虽有较多结瘤,但根瘤数量较nts382减少近3/4。因此,认为不结瘤品系nod49不结瘤由根部控制,地上部分对根部结瘤产生影响[65]。Francisco等利用结瘤正常品系Enrei、超结瘤突变品系En6500与不结瘤品系Enll5、En1282、Enl314分别作地上部和地下部互相嫁接,嫁接结论与Delves等一致,即不结瘤品系为嫁接地下部分时,无论地上部嫁接是正常品系还是超结瘤品系,根瘤数量均表现为0,而以不结瘤品系为嫁接地上部分,以结瘤正常品系Enrei为嫁接地下部分,根瘤数量比Enrei略减,以超结瘤突变体En6500为嫁接地下部分虽有结瘤,但结瘤数量比超结瘤En6500减少近25倍[73]。Carroll等对超结瘤及氮素忍耐品种筛选后及不同氮浓度条件下试验认为,超结瘤大豆品系nts382受根瘤发展调节基因影响,与硝酸盐同化基因无关[79]。表明从基因角度分析AON与氮素抑制结瘤关系机制需深入探究。

2.5 其他可能抑制机制

Tanner和Anderson提出氮素通过减少额外的吲哚乙酸(IAA)浓度抑制结瘤[80]。Bano和Harper等通过研究大豆接种前后木质部、韧皮部及叶片中激素变化表明,在接种根瘤菌6 h后,木质部ABA(脱落酸)浓度增加,而韧皮部和叶片部ABA浓度在接种48~96 h后发生变化,认为激素在根部结瘤自动调节方面发挥重要作用[81]。Ligero等研究认为,NO3-对根瘤抑制作用可通过乙烯抑制剂(Aminoethoxyvinylglycine,AVG)消除,提出NO3-抑制影响通过植物激素乙烯介导,指出内源乙烯在根瘤自动调节系统中发挥重要作用[82]。Zhang等对拟南芥发现硝酸盐对植物激素反应产生影响,因此硝酸盐对豆科作物可通过植物激素产生间接影响[83]。Caba等认为硝酸盐降低野生品种和突变品种结瘤和不结瘤大豆植物激素水平,根生长未改变[84]。Fei和Vessey以蒺藜苜蓿(Medicago truncatula)为试验材料研究发现,低浓度铵态氮促进苜蓿结瘤(根瘤数量和重量),而ABA(脱落酸)活性蛋白激酶和GA(赤霉素)调节蛋白基因编码对不同浓度硝态氮和铵态氮回应较少,但在多种处理间乙烯反应的连接因子基因表达明显增加。3个生长素相关基因和3个细胞分裂素相关基因则表现对硝态氮和铵态氮不同回应。虽然根部有较高比例的细胞分裂素和生长素,但不能说明其促进结瘤潜在机制[85]。Peters等研究指出,在根瘤菌中结瘤基因被寄主植株根中的信号混合物类黄酮和异黄酮激活[86-87]。Redmond等指出,根部黄酮类物质诱导结瘤基因表达,并与根瘤菌内部信号交流[88]。Cho和Harper利用PVC管将大豆根平分为两部分,施用5 mmol·L-1硝态氮的一侧根,根瘤数量、重量、固氮酶活性均显著小于应用0 mmol·L-1硝态氮一侧根,施氮侧根异黄酮浓度明显较低,因此推测氮最初对结瘤处抑制是因异黄酮水平降低[89]。这也暗示氮素对根瘤抑制机制与多类植物激素有关,而在其中发挥重要作用激素的具体调节机制仍需深入研究。

3 问题与展望

自1916年Fred指出氮素阻碍根瘤发展以来,氮素抑制豆类作物根瘤固氮研究受到关注,但具体抑制机制并无实质性突破。目前,氮素抑制豆类作物根瘤固氮仍无定论。

①由氮素形态对结瘤抑制试验可见,不同形态氮对结瘤和固氮酶活性抑制效果不同,硝态氮对根瘤生长发育及固氮酶活性抑制作用较铵态氮更强。揭示硝态氮、铵态氮抑制大豆根瘤形成至少有两种作用机制。铵态氮抑制根瘤固氮机制与硝态氮是否有重叠交叉过程尚待深入研究。

②氮浓度研究结果可见,氮浓度界限不清,对大豆结瘤及固氮产生影响的浓度范围模糊,浓度范围界定仍需系统化、标准化研究。

③分根和局部供氮方法研究认为,氮素抑制根瘤形成与发育存在局部性,而固氮酶活性则存在系统性。但仍有疑点,如氮素抑制根瘤形成短期与长期条件下是否均呈局部性,不同氮素浓度下抑制作用是否可逆,在不同氮素形式下恢复是否不同,氮素抑制根瘤局部性是否与不同生长介质影响有关等。分根法研究氮素与根瘤抑制关系具有优势,但介质中溶液培养试验较多,其他介质环境试验较少,氮素对结瘤抑制多方面影响研究仍无实质性突破。

④豆类作物种类众多,符合某种抑制机制的豆类作物是否符合其他抑制机制。多种豆类作物是否拥有一种或几种共同抑制机制,或差异共存,有待深入研究。

[1]Fred E B,Graul E J.The Effect of soluble nitrogenous salts on nodule formation[J].Agronomy Journal,1916,8(5):316-328.

[2]刘莉,周俊初,陈华癸.不同化合态氮浓度对大豆根瘤菌结瘤和固氮作用的影响[J].中国农业科学,1998(4):87-89.

[3]Guo R Q,Silsbury J H,Graham R D.Effect of four nitrogen compounds on nodulation and nitrogen fixation in faba bean,white pupin and medic plants[J].Australian Journal of Plant Physiology, 1992,19:501-508.

[4]严君,韩晓增,王守宇,等.不同形态氮对大豆根瘤生长及固氮的影响[J].大豆科学,2009(4):674-677.

[5]Gan Y,Stulen I,Keulen H V,et al.Low concentrations of nitrate and ammonium stimulate nodulation and N2fixation while inhibiting specific nodulation(nodule DW g-1 root dry weight)and specific N2fixation(N2fixed g-1 root dry weight)in soybean[J].Plant and Soil,2004,258(1):281-292.

[6]董守坤,刘丽君,孙聪姝,等.利用15N标记研究氮素水平对大豆根瘤生长的影响[J].植物营养与肥料学报,2011(4):985-988.

[7]宋海星,申斯乐,马淑英,等.硝态氮和氨态氮对大豆根瘤固氮的影响[J].大豆科学,1997(4):8-12.

[8]Svenning M M,Junttila O,Macduff J H.Differential rates of inhibition of N2fixation by sustained low concentrations of NH4+and NO3-in northern ecotypes of white clover(Trifolium repens L.)[J]. Journal of Experimental Botany,1996,47(6):729-738.

[9]Rys G J,Phung T.Effect of nitrogen form and counterion on establishment of the Rhizobium trifolii-Trifolium repens symbiosis[J]. Journal of Experimental Botany,1984,35(12):1811-1819.

[10]Wahab A M A,Abd-Alla M H.Effect of different rates of N-fertilizers on nodulation,nodule activities and growth of two field grown cvs.of soybean[J].Nutrient Cycling in Agroecosystems, 1995,43(1):37-41.

[11]Gulden R H,Vessey J K.The stimulating effect of ammonium on nodulation in Pisum sativum L.is not long lived once ammonium supply is discontinued[J].Plant and Soil,1997,195(1):195-205.

[12]Imsande J.Inhibition of nodule development in soybean by nitrate or reduced nitrogen[J].Journal of Experimental Botany, 1986,37(3):348-355.

[13]Gulden R H,Vessey J K.Low concentrations of ammonium inhibit specific nodulation(nodule number g-1,root DW)in soybean (Glycine max[L.]Merr.)[J].Plant and Soil,1998,198(2):127-136.

[14]Forde B G,Clarkson D T.Nitrate and ammonium nutrition of plants:Physiological and molecular perspectives[J].Adv Bot Res, 1999,30(8):1-90.

[15]Saravitz C H,Chaillou S,Musset J,et al.Influence of nitrate on uptake of ammonium by nitrogen-depleted soybean:is the effect located in roots or shoots?[J].Journal of Experimental Botany, 1994,45(11):1575-1584.

[16]Hansen A P,Rerkasem B,Lordkaew S.Does ammonium uptake influence xylem sap composition in Phaseolus vulgaris L.and Glycine max(L.)Merill?[J].Experientia,1995,51(11):1085-1089.

[17]Daimon H,Hori K,Shimizu A,et al.Nitrate-Induced inhibition of root nodule formation and nitrogenase activity in the peanut (Arachis hypogaea L.)[J].Plant Production Science,1999,2(2): 81-86.

[18]Macduff J H,Jarvis S C,Davidson I A.Inhibition of N2fixation by white clover(Trifolium repens L.)at low concentrations of NO3-in flowing solution culture[J].Plant and Soil,1996,180(2):287-295.

[19]Carroll B J,Gresshoff P M.A supernodulation and nitrate-tolerant symbiotic(Nts)soybean mutant[J].Plant Physiology,1985,78 (1):34-40.

[20]Saito A,Tanabata S,Tanabata T,et al.Effect of nitrate on nodule and root growth of soybean(Glycine max(L.)Merr.)[J].International Journal of Molecular Sciences,2014,15(3):4464-4480.

[21]Serraj R,Drevon J J,Obaton M,et al.Variation in nitrate tolerance of nitrogen fixation in soybean(Glycine max)—Bradyrhizobium symbiosis[J].Journal of Plant Physiology,1992,140(3):366-371.

[22]张荣铣,Laren R R,Bruce N S.硝态氮对于大豆幼苗生长、根瘤固氮及光合产物运转的影响[J].南京农学院学报,1984(2): 1-8.

[23]Streeter J,Wong P P.Inhibition of legume nodule formation and N2fixation by nitrate[J].Critical Reviews in Plant Sciences,1988, 7(1):1-23.

[24]Gibson A H,Harper J E.Nitrate effect on nodulation of soybean by Bradyrhizobium japonicum[J].Crop Science,1985,25(3):497-501.

[25]Minchin F R,Witty J F.Further errors in the acetylene reduction assay:Effects of plant disturbance[J].Journal of Experimental Botany,1986,37(10):1581-1591.

[26]Schuller K A,Gresshoff P M.Enzymes of ammonia assimilation and ureide biosynthesis in soybean nodules:Effect of nitrate[J]. Plant Physiology,1986,80(3):646-650.

[27]Arrese-Igor C,Minchin F R,Gordon A J,et al.Possible causes of the physiological decline in soybean nitrogen fixation in the presence of nitrate[J].Journal of Experimental Botany,1997,48(4): 905-913.

[28]Chamber-Pérez M A,Camacho-Martínez M,Soriano-Niebla J J. Nitrate-reductase activities of Bradyrhizobium,spp.in tropical legumes:Effects of nitrate on O2,diffusion in nodules and carbon costs of N2,fixation[J].Journal of Plant Physiology,1997,150(1-2):92-96.

[29]Serrano A,Chamber M.Nitrate reduction in Bradyrhizobium sp.(Lupinus)strains and its effects on their symbiosis with Lupinus luteus.[J].Journal of Plant Physiology,1990,136(2):240-246.

[30]Streeter J G.Nitrate inhibition of legume nodule growth and activity.II.Short-term studies with high nitrate supply[J].Plant Physiol,1985,77:325-328.

[31]Skrdleta V,Gaudinová A,Němcová M,et al.Symbiotic dinitrogen fixation as affected by short-term application of nitrate to nodulated Pisum sativum L.[J].Folia Microbiologica,1980,25(2):155-161.

[32]Kennedy I R,Rigaud J,Trinchant J C.Nitrate reductase from bacteroids of Rhizobium japonicum:Enzyme characteristics and possible interaction with nitrogen fixation[J].Biochimica Et Biophysica Acta,1975,397(1):24-35.

[33]Kato K,Kanahama K,Kanayama Y.Involvement of nitric oxide in the inhibition of nitrogenase activity by nitrate in lotus root nodules[J].Journal of Plant Physiology,2010,167(3):238-241.

[34]Hinson K.Nodulation responses from nitrogen applied to soybean half-root systems[J].Agronomy Journal,1975,67:799-804.

[35]Carroll B J,Gresshoff P M.Nitrate inhibition of nodulation and nitrogen fixation in white clover[J].Zeitschrift Fü Pflanzenphysiologie,1983,110(1):77-88.

[36]Silsbury J H,Catchpoole D W,Wallace W.Effects of nitrate and ammonium on nitrogenase(C2H2reduction)activity of swards of subterranean clover,Trifolium subterraneum L.[J].Functional Plant Biology,1986,13(2):257-273.

[37]Pankhurst C E.Effect of plant nutrient supply on nodule effectiveness and rhizobium strain competition for nodulation of Lotus pedunculatus[J].Plant and Soil,1981,60(3):325-339.

[38]Kohls S J,Baker D D.Effects of substrate nitrate concentration on symbiotic nodule formation in actinorhizal plants[J].Plant and Soil,1989,118(1):171-179.

[39]Arnone J A,Kohls S J,Baker D D.Nitrate effects on nodulation and nitrogenase activity of actinorhizal Casuarina studied in splitroot systems.[J].Soil Biology&Biochemistry,1994,26(5):599-606.

[40]Tanaka A,Fujlta K,Terasawa H.Growth and dinitrogen fixation, of soybean root system affected by partial exposure to nitrate[J]. Soil Science and Plant Nutrition,1985,31(4):637-645.

[41]Daimon H,Yoshioka M.Responses of root nodule formation and nitrogen fixation activity to nitrate in a split-root system in peanut(Arachis hypogaea L.)[J].Journal of Agronomy and Crop Science,2001,187(2):89-95.

[42]Zaman M,Saggar S,Blennerhassett J D,et al.Effect of urease and nitrification inhibitors on N transformation,gaseous emissions of ammonia and nitrous oxide,pasture yield and N uptake in grazed pasture system[J].Soil Biology&Biochemistry,2009,41(6): 1270-1280.

[43]Orcutt F S,Wilson P W.The effect of nitrate-nitrogen on the carbohydrate metabolism of inoculated soybeans[J].Soil Science, 1935,39(4):289-296.

[44]Stephens B D,Neyra C A.Nitrate and nitrite reduction in relation to nitrogenase activity in soybean nodules and Rhizobium japonicum bacteroids.[J].Plant Physiology,1983,71(4):731-735.

[45]Houwaard F.Influence of ammonium and nitrate nitrogen on nitrogenase activity of pea plants as affected by light intensity and sugar addition[J].Plant and Soil,1980,54(2):271-282.

[46]Wong P P.Nitrate and carbohydrate effects on nodulation and nitrogen fixation(acetylene reduction)activity of lentil(Lens esculenta Moench)[J].Plant Physiology,1980,66(1):78-81.

[47]Small J G C,Leonard O A.Translocation of14C labeled photosynthate in nodulated legumes as influenced by nitrate nitrogen[J]. Amer J Bot,1969,56(2):187-194.

[48]Khan A A,Khan A A.Effects of nitrate nitrogen on growth,nodulation and distribution of14C-labelled photosynthates in cowpea[J]. Plant and Soil,1981,63(2):141-147.

[49]Bacanamwo M,Harper J E.Regulation of nitrogenase activity in Bradyrhizobium japonicum soybean symbiosis by plant N status as determined by shoot C:N ratio[J].Physiologia Plantarum, 1996,98(3):529-538.

[50]Singleton P W,Van K C.Effect of localized nitrogen availability to soybean half-root systems on photosynthate partitioning to roots and nodules[J].Plant Physiology,1987,83(3):552-556.

[51]Minchin F R,Minguez M I,Sheehy J E,et al.Relationships between nitrate and oxygen supply in symbiotic nitrogen fixation by white clover[J].Journal of Experimental Botany,1986,37(8): 1103-1113.

[52]Carroll B J,Hansen A P,Mcneil D L,et al.Effect of oxygen supply on nitrogenase activity of nitrate-and dark-stressed soybean (Glycine max(L.)Merr.)plants[J].Functional Plant Biology,1987, 14(6):679-687.

[53]Minchin F R,Becana M,Sprent J I.Short-term inhibition of legume N2fixation by nitrate:II.Nitrate effects on nodule oxygen diffusion[J].Planta,1989,180(1):46-52.

[54]Arrese-Igor C,García-Plazaola J I,Hernández A,et al.Effect oflow nitrate supply to nodulated lucerne on time course of activities of enzymes involved in inorganic nitrogen metabolism[J]. Physiologia Plantarum,1990,80(2):185-190.

[55]Arrese-Igor C,Royuela M,Aparicio-Tejo P M.Denitrification in lucerne nodules and bacteroids supplied with nitrate[J].Physiologia Plantarum,1992,84(4):531-536.

[56]Munns D N.Nodulation of Medicago sativa in solution culture:Ⅲ.Effects of nitrate on root hairs and infection[J].Plant&Soil, 1968,29(1):33-47.

[57]Wahab A M A,Zahran H H,Abd-Alla M H.Root-hair infection and nodulation of four grain legumes as affected by the form and the application time of nitrogen fertilizer[J].Folia Microbiologica, 1996,41(4):303-308.

[58]Wang R,Xing X,Crawford N.Nitrite acts as a transcriptome signal at micromolar concentrations in Arabidopsis roots[J].Plant Physiology,2007,145(4):1735-1745.

[59]Forde B G.Local and long range signalling pathways regulating plant response to nitrate[J].Annual Review of Plant Biology, 2002,53(1):203-224.

[60]Becana M,Aparicio-Tejo P M,Sánchez-Díaz M.Nitrate and nitrite reduction by alfalfa root nodules:Accumulation of nitrite in Rhizobium melioti,bacteroids and senescence of nodules[J]. Physiologia Plantarum,1985,64(3):353-358.

[61]Wasfi M,Prioul J L.A comparison of inhibition of French-bean and soybean nitrogen fixation by nitrate,1%oxygen or direct assimilate deprivation[J].Physiologia Plantarum,1986,66(3):481-490.

[62]Nelson L M,Edie S A.Effect of nitrate on nitrogen fixation and nodule carbohydrate and organic acid concentrations in pea mutants deficient in nitrate reductase[J].Physiologia Plantarum, 1988,73(4):534-540.

[63]Chen P C,Phillips D A.Induction of root nodule senescence by combined nitrogen in Pisum sativum L.[J].Plant Physiology, 1977,59(3):440-442.

[64]Kosslak R M,Bohlool B B.Suppression of nodule development of one side of a split-root system of soybeans caused by prior inoculation of the other side[J].Plant Physiology,1984,75(1):125-130.

[65]Delves A C,Mathews A,Day D A,et al.Regulation of the soybean-Rhizobium nodule symbiosis by shoot and root factors[J]. Plant Physiology,1986,82(2):588-590.

[66]Reid D E,Ferguson B J,Hayashi S,et al.Molecular mechanisms controlling legume autoregulation of nodulation[J].Annals of Botany,2011,108(5):789-795.

[67]Caetano-Anollés G,Gresshoff P M.Early induction of feedback regulatory responses governing nodulation in soybean[J].Plant Science,1990,71(1):69-81.

[68]Caetano-Anollés G,Gresshoff P M.Plant genetic control of nodulation[J].Annu Rev Microbiol,1991,45:345-382.

[69]Ito S,Kato T,Ohtake N,et al.The autoregulation of nodulation mechanism is related to leaf development[J].Plant Cell Physiol, 2008,49(1):121-125.

[70]Neo H H,Layzell D B.Phloem glutamine and the regulation of O2diffusion in legume nodules[J].Plant Physiology,1997,113(1): 259-267.

[71]Searle I R,Men A E,Laniya T S,et al.Long-distance signaling in nodulation directed by a CLAVATA1-like receptor kinase[J]. Science,2003,299(5603):109-112.

[72]Reid D E,Ferguson B J,Gresshoff P M.Inoculation-and nitrateinduced CLE peptides of soybean control NARK-dependent nodule formation[J].Molecular Plant-Microbe Interactions,2011,24 (5):606-618.

[73]Francisco P B,Akao S.Autoregulation and nitrate inhibition of nodule formation in soybean cv.enrei and its nodulation mutants [J].Journal of Experimental Botany,1993,44(3):547-553.

[74]Buttery B R,Park S J.Effects of nitrogen,inoculation and grafting on expression of supernodulation in a mutant of Phaseolus vulgaris L[J].Canadian Journal of Plant Science,1990,70(2):375-381.

[75]Gremaud M F,Harper J E.Selection and initial characterization of partially nitrate tolerant nodulation mutants of soybean[J]. Plant Physiology,1989,89(1):169-173.

[76]Ohyama T,Nicholas J C,Harper J E.Assimilation of15N2and15NO3-by partially nitrate-tolerant nodulation mutants of soybean[J].Journal of Experimental Botany,1993,44(12):1739-1747.

[77]Day D A,Carroll B J,Delves A C,et al.Relationship between autoregulation and nitrate inhibition of nodulation in soybeans[J]. Physiologia Plantarum,1989,75(1):37-42.

[78]Hamaguchi H,Kokubun M,Akao S.Shoot control of nodulation is modified by the root in the supernodulating soybean mutant En6500 and its wild-type parent cultivar enrei[J].Soil Science and Plant Nutrition,1992,38(4):771-774.

[79]Carroll B J,Mcneil D L,Gresshoff P M.Isolation and propertiesof soybean[Glycine max(L.)Merr.]mutants that nodulate in the presence of high nitrate concentrations[J].Proceedings of the National Academy of Sciences of the United States of America, 1985,82(12):4162-4166.

[80]Tanner J W,Anderson I C.External effect of combined nitrogen on nodulation[J].Plant Physiology,1964,39(6):1039-1043.

[81]Bano A,Harper J E,Auge R M,et al.Changes in phytohormone levels following inoculation of two soybean lines differing in nodulation[J].Functional Plant Biology,2002,29(8):965-974.

[82]Ligero F,Caba J M,Lluch C,et al.Nitrate inhibition of nodulation can be overcome by the ethylene inhibitor aminoethoxyvinylglycine[J].Plant Physiology,1991,97(3):1221-1225.

[83]Zhang H,Jennings A,Barlow P W,et al.Dual pathways for regulation of root branching by nitrate[J].Proceedings of the National Academy of Sciences of the United States of America,1999,96 (11):6529-6534.

[84]Caba J M,Centeno M L,Fernández B,et al.Inoculation and nitrate alter phytohormone levels in soybean roots:Differences between a supernodulating mutant and the wild type[J].Planta, 2000,211(1):98-104.

[85]Fei H,Vessey J K.Stimulation of nodulation in Medicago truncatula by low concentrations of ammonium:Quantitative reverse transcription PCR analysis of selected genes[J].Physiologia Plantarum,2009,135(3):317-330.

[86]Peters N K,Frost J W,Long S R.A plant flavone,luteolin,induces expression of Rhizobium meliloti nodulation genes[J].Science, 1986,233(4767):977-980.

[87]Kosslak R M,Appelbaum E R.Induction of Bradyrhizobium japonicum common nod genes by isoflavones isolated from Glycine max[J].Proceedings of the National Academy of Sciences of the United States of America,1987,84(21):7428-7432.

[88]Redmond J W,Batley M,Djordjevic M A,et al.Flavones induce expression of nodulation genes in Rhizobium[J].Nature,1986, 323:632-635.

[89]Cho M J,Harper J E.Effect of localized nitrate application on isoflavonoid concentration and nodulation in split-root systems of wild-type and nodulation-mutant soybean plants[J].Plant Physiology,1991,95(4):1106-1112.

Research advance on the relationship between nitrogen and Leguminous

nitrogen fixation

XIA Xuan,GONG Zhenping(School of Agriculture,Northeast Agricultural

University,Harbin 150030,China)

The relationship between nitrogen and nodule nitrogen fixation is very delicate.It is necessary to combine the two to achieve high yield.However,the contradiction between the two has a great negative impact on nodule nitrogen fixation.However,the mechanism of how nitrogen affects root nodulation is still unclear.Based on previous studies,the research progress of the relationship between nitrogen fixation and nitrogen fixation of soybean was summarized.The effects of different nitrogen forms and nitrogen concentration on nodule formation and growth,nitrogenase activity and related mechanisms were reviewed. The mechanism of carbohydrate competition,inhibition of nitrogen supply mechanism,nitrate toxicity mechanism,feedback regulation mechanism and other possible inhibition mechanisms of nitrogen fixation were discussed.And put forward the nitrogen inhibition nodules of nitrogen boundaries blurred.Different nitrogen forms and legume species nitrogen inhibition mechanism differentiation and detailed inhibition mechanism was not clear and so on.

nitrogen;nodule;inhibition;mechanism

S565.1

A

1005-9369(2017)01-0079-10

2016-11-28

国家科技支撑项目(2014BAD11B01)

夏玄(1988-),女,博士研究生,研究方向大豆栽培生理。E-mail:731275750@qq.com

*通讯作者:龚振平,教授,博士生导师,研究方向为保护性耕作和大豆生理。E-mail:gzpyx2004@163.com

时间2017-1-9 15:46:07[URL]http://www.cnki.net/kcms/detail/23.1391.S.20170109.1546.012.html

夏玄,龚振平.氮素与豆科作物固氮关系研究进展[J].东北农业大学学报,2017,48(1):79-88.

Xia Xuan,Gong Zhenping.Research advance on the relationship between nitrogen and Leguminous nitrogen fixation[J]. Journal of Northeast Agricultural University,2017,48(1):79-88.(in Chinese with English abstract)

猜你喜欢

结瘤根瘤固氮
日钢4#高炉结瘤原因及处理措施
不同时间输液法输液对樱桃根癌病的防控效果研究
海洋生物固氮研究进展
铜工业电解条件下结瘤的生长行为研究
不同处理方法对樱桃根瘤病的防控效果
SAE8620H齿轮钢连铸水口结瘤的原因及预防措施
GCr15钢浇注过程浸入式水口结瘤的原因及控制
果树苗木根瘤病发生规律及其防控技术
基于15N 示踪法的双根大豆系统氮素吸收和分配特性研究
杉木与固氮树种混交对土壤有机质及氮含量的影响