1 氮效率的评价指标
氮效率是指利用单位氮素生产干物质或籽粒产量的能力,从作物对氮肥的吸收和利用等角度,可分为氮素吸收利用率、生理利用率、农学利用率、氮肥偏生产力、氮收获指数、氮素干物质生产效率和氮素籽粒生产效率等,其中氮素吸收利用率指施氮区与空白区氮积累量的差值占总施氮量的比值,生理利用率指施氮区与空白区氮积累量的差值与氮积累量增加量的比值,农学利用率指施氮后作物产量增加量与施氮量的比值,氮肥偏生产力指施氮后作物的产量与施氮量的比值,氮收获指数指籽粒氮积累量与植物总氮积累量的比值,氮素干物质生产效率指作物干物质积累量与总氮积累量的比值,氮素籽粒生产效率指作物产量与总氮积累量的比值[1,10]。因此,提高氮效率,一方面要在有限养分供应量下提高氮肥吸收效率,另一方面是在相同或者较低氮供应量或氮积累量下生产出更多的干物质或籽粒产量。氮效率与植株根系紧密相关,目前,关于作物根系形态、解剖以及生理学特征与氮效率关系的研究较多。
2 根系形态特征与氮效率
关于作物根系分布、总根长、根表面积、根体积、侧根和根毛与氮素吸收利用效率关系的研究见表1。
表1 作物根系形态特征与氮素吸收利用效率的关系
Table 1
| 根系性状 Root trait | 与氮吸收利用效率的关系 Correlations with nitrogen uptake and utilization efficiency | 参考文献 Reference |
|---|---|---|
| 根系分布Root distribution | 高产、高氮吸收利用率的水稻品种在10cm以下土层有较大的根干重、根表面积和根体积 | [11-12] |
| 总根长、根表面积、根体积 Total root length, root surface area, root volume | 氮积累量和氮利用效率高的水稻品种通常具有较大的总根长、根表面积和根体积 | [13-20] |
| 侧根Lateral root | 侧根数以及侧根长与氮积累量呈正相关关系 | [15,21-23] |
| 根毛Root hair | 长且密的根毛可提高水稻对氮、磷、钾等养分的吸收效率 | [8,24-27] |
2.1 根系分布
土壤中根系分布影响植物对土壤资源的吸收利用。水稻根系主要分布于0~20cm土壤耕作层,上层根（0~10cm）占总根量的80%[11,12]。在干旱和缺氮条件下,深扎根系更容易获得较多的氮和水分[8,28-29]。蔡昆争等[11]认为,适当减少表层土壤根系和增加深层土壤根系有利于增加水稻产量。与浅根系水稻IR64相比,含有深根控制位点DRO1的近等基因系深层根系分布显著增加,提高了低氮下水稻产量和氮素利用效率[30]。一方面,水稻根系分布影响地上部性状,根系纵向分布且深扎的水稻植株往往叶片易直立,叶角更小,有利于改善群体通风透光条件,提高群体光合作用和产量[31]。另一方面,根系分布特征也影响着根系生理生化特征,如与浅根水稻相比,深根水稻根系中与能量代谢相关的基因表达量高,ATP产生快,根系伤流液中的细胞分裂素（CTKs）含量高[30,32],可能有利于根系氮素吸收和地上部生长。因此,根系深扎是提高水稻氮素吸收利用率的重要根系特征。
2.2 根长与根表面积
发达的根系是作物氮素高效吸收的保证,吸氮能力强、氮积累量多的水稻品种往往具有较大的根生物量、总根长和根表面积[13,14,15,16]。然而,在一些情况下,根系进行冗余生长,根长和根冠比等与产量和氮素吸收呈负相关[11];刘桃菊等[17]通过模型分析发现,在水稻齐穗期根数少时,一定范围内增加根长和根重可显著提高产量;但随着根长和根重继续增加,产量则开始下降。一些根干重、总根长和根表面积较低的水稻品种在低氮胁迫下也具有较高的氮素利用效率,可能与这些品种生育后期的根系活力、根系伤流量和活跃吸收表面积高有关[18,19]。因此,根系大小对产量和氮素吸收利用率形成的作用取决于作物品种、生长环境和生育时期等。
2.3 侧根与根毛
水稻侧根与地上部生长和氮素吸收利用率的关系一直被人们关注[7]。侧根密度与株高、分蘖以及单株产量呈显著正相关[20]。水稻侧根发生受供氮水平调控并且影响氮吸收,短期氮饥饿和局部供氮都能诱导水稻侧根形成,从而促进氮吸收[21,22]。Postma等[23]通过SimRoot模型模拟玉米侧根与氮吸收利用率关系时发现,玉米最适侧根密度随施氮量增加而增加,过高或过低的侧根密度都不利于地上部生物量积累,过高的侧根密度会降低根系氮素吸收效率,并可能造成根系冗余而增加根系代谢成本（如氮、碳占用和呼吸消耗）,影响生物量积累和产量形成。目前,关于水稻侧根与氮素吸收利用率关系的研究较少,侧根密度和长度影响水稻氮素吸收利用率的机理值得进一步研究。
3 根系解剖结构与氮效率
表2 作物根系解剖特征与氮素吸收利用效率的关系
Table 2
| 根系性状 Root trait | 与氮吸收利用效率的关系 Correlations with nitrogen uptake and utilization efficiency | 参考文献 Reference |
|---|---|---|
| 根直径、根中柱Root diameter, root stele | 氮素吸收利用率高的水稻品种具有较多的粗分枝根 | [35-42] |
| 根皮层性状Root cortical traits | 皮层细胞层数少、皮层细胞大会降低玉米根系的呼吸代谢消耗,提高抗逆性 | [43-46] |
| 根通气组织Root aerenchyma | 根通气组织的形成可提高玉米低氮下的氮素利用效率,氮素吸收利用率高的水稻品种也具有较多的根通气组织 | [47-54] |
| 根木质化和栓质化 Root lignification and suberization | 水稻根木质化和栓质化水平在低氮下降低,与氮吸收呈负相关关系 | [55-59] |
3.1 根直径和中柱
3.2 根皮层
通气组织是根皮层薄壁组织空腔或气室的集合。不同水稻品种间根通气组织的大小存在着基因型差异,同一品种随着生育期推进而根通气组织逐渐增加[47]。此外,水稻通气组织形成还受逆境胁迫的调控,缺氮、缺氧和干旱等逆境可诱导水稻根通气组织的形成[33,48-49]。通气组织的形成可提高根系泌氧能力,可在缺氧条件下更有效地传输氧气[48,49],也能通过提高土壤氧化还原电势来促进土壤硝化作用和增加土壤氮含量[50]。另一方面,通气组织是植物通过减少根系能量消耗来应对逆境胁迫的一种适应性反应[51],Saengwilai等[52]通过模拟研究发现,根通气组织增加10%时,根氮含量和单位根长的呼吸速率降低50%,低氮胁迫下扎根深度增加15%~31%,作物产量增加58%,表明通气组织形成降低了根代谢需求,更多的物质和能量用于深扎根的构建,提高了植株氮素利用效率和耐低氮能力[52,53]。在水稻中,与程序化死亡相关的基因如OsBhpi008a、OsPDCD5和OsPAD4参与了缺氧胁迫下水稻根通气组织形成,一些与根通气组织形成相关的数量性状位点的表达可以促进淹水胁迫下水稻的干物质积累[54],这表明通气组织的形成有利于干物质积累。
3.3 根木质化和栓质化
4 根系生理生化特性
关于NO3-和NH4+转运基因、氮同化酶活性、根呼吸代谢途径、根系分泌物和根活力与氮素吸收利用效率关系的研究见表3。
表3 作物根系生理特征与氮素吸收利用效率的关系
Table 3
| 根系性状 Root trait | 与氮吸收利用效率的关系 Correlations with nitrogen uptake and utilization efficiency | 参考文献 Reference |
|---|---|---|
| NO3-和NH4+转运基因 NO3- and NH4+ transporter genes | OsNRT2.3b和OSAMT1;1高表达提高水稻的氮素吸收利用率 | [61-62] |
| 氮同化酶活性 Nitrogen-assimilating enzyme activity | 氮素吸收利用率高的的水稻品种通常具有较高的根系硝酸还原酶（NR）、亚硝酸还原酶（NiR）、谷氨酰胺合酶（GS）、谷氨酸合酶（GOGAT）和谷氨酸脱氢酶（GDH）活性,根系氮同化能力强 | [63] |
| 根呼吸代谢途径Root respiratory pathway | 氮素吸收利用率高的品种根系细胞色素氧化酶活性和呼吸代谢途径产能效率高 | [64] |
| 根系分泌物Root exudates | 氮素吸收利用率高的水稻品种根系分泌物中的有机酸和氨基酸较少 | [65-66] |
| 根活力Root vigor | 高产、高氮素吸收利用率的水稻品种具有较高的根系活力 | [12,18-19] |
4.1 根系氮吸收和转运
氮素吸收利用率高的水稻品种在低氮下往往具有较强的氮素吸收能力,与氮素转运蛋白紧密相关[6,16]。高的根系氮素转运基因表达是植株应对低氮胁迫的一种策略,一是增强根系氮素吸收能力,在建成相同甚至较小根系时植株也能在生育前期积累较多的氮素[6,61];二是增强植株光合能力,Ranathunge等[61]发现转OsAMT1.1基因植株具有高的光合速率和同化物生产力,增加了氮素利用效率。此外,土壤微生物群落结构的差异影响水稻对氮的吸收,例如NRT1.1B在籼粳稻间的自然变异影响水稻根际微生物群落结构,籼稻根际比粳稻富集更多与氮循环相关的微生物群落,这可能是籼稻具有较强NO3-吸收和利用能力的重要原因[67]。近年来,人们通过分子生物学手段增加作物氮素转运基因表达,促进作物氮吸收,较好地实现了“减氮增效”,例如,NO3-转运基因OsNRT1.1A、OsNRT1.1B、OsNRT2.3b和OSNPF6.1的超表达增强了水稻植株NO3-的吸收能力,提高了产量和氮素利用效率[62,68-69]。
NO3-吸收进入植物体内后的分配和长距离转运影响植株的氮利用率[70]。通道蛋白CLC定位于液泡膜,负责将NO3-转运至根液泡暂时储存,CLC低表达时根液泡中的储存NO3-量减少,有利于NO3-向地上部分配和利用[71];NRT1家族的OsNPF7.2蛋白定位于水稻液泡膜,可能调控NO3-在根细胞内的短途分配[72]。目前,在拟南芥和油菜等植物中已明确了由NRT1.5和NRT1.8蛋白介导的NO3-向地上部长途转运机制,NRT1.5受NO3-的诱导在根中柱细胞中表达,负责将NO3-从中柱鞘细胞中运出并装载到根木质部;与NRT1.5作用相反,NRT1.8负责根木质部NO3-的卸载;在低氮胁迫下氮吸收利用率高的油菜品种通过显著提高NRT1.5而降低NRT1.8的表达,从而促进NO3-向地上部转运,因此具有较高的氮素利用效率[6,70]。水稻OsNRT2.3a、OsNPF2.2和OsNPF2.4都参与了NO3-从根系向地上部的长距离转运,这些基因突变导致NO3-向地上部运输受阻,生物量和产量降低[64,72-73]。由此可见,促进根系氮吸收和向地上部转运是提高水稻氮素吸收效率的重要途径。
4.2 根系氮同化
植物根系吸收的部分无机态氮（NO3-、NH4+）在根经过硝酸还原酶（NR）、亚硝酸还原酶（NiR）、谷氨酰胺合酶（GS）、谷氨酸合酶（GOGAT）和谷氨酸脱氢酶（GDH）等酶的作用被还原为有机态氮（谷氨酰胺等）,并与无机氮一起通过木质部运往地上部[74]。研究表明,氮素吸收利用率高的品种根系往往具有高的NR和GS活性[63,75],且在低氮下能维持较高的NR、GS和GDH活性[76]。根系氮同化酶活性不仅影响水稻氮同化量,还与氮素向地上部的运输有关,如Kiyomiya等[77]用GS抑制剂处理水稻植株后,13N向地上部运输减少并在根中积累,OsGS1;2基因缺失的水稻突变体根中大量积累游离NH4+,生物量和产量显著降低[78],其原因可能是根系氮同化酶活性降低导致NH4+不能及时被同化利用。另外,OsAMT1;2和OsGOGAT1同时超表达可显著提高低氮下水稻的产量和氮素吸收利用率[78,79,80]。OsNR2在籼粳稻间存在基因变异,含有籼稻OsNR2等位基因的粳稻近等基因家系植株在低氮下氮素吸收能力显著增强,具有较高的根系NR活性、产量和氮素吸收利用率[81]。因此,高的氮同化酶活力是水稻氮素吸收利用率高的重要根系生理特征。
4.3 根系呼吸代谢途径
植物通过多种呼吸代谢途径和电子传递链途径来适应逆境胁迫,如在低磷和低氮养分胁迫时,植物增加磷酸戊糖途径（PPP）,降低糖酵解-三羧酸循环途径（EMP-TCA）;增加交替途径（AP）,降低细胞色素途径（CP）等[82,83]。当植物PPP和AP途径升高,而EMP-TCA和CP途径下降,表示植株可能正在遭受逆境胁迫或处于“亚健康”状态,往往伴随着生长速率和生物量下降[83,84]。在营养缺乏条件下,耐贫瘠品种能保持较高的EMP-TCA和CP途径,维持较高呼吸产能效率,植株相对生长效率受逆境胁迫影响小[83]。氮吸收效率高的水稻品种具有较高的根系细胞色素氧化酶活性和ATP含量,对氮素的亲和力更强,根系高的呼吸产能效率是水稻品种氮素吸收利用率高的重要生理机制[64]。
4.4 根系分泌物
4.5 根际微生物与氮素吸收利用率
根际微生物是指定植于植物根际区域的微生物,能活化土壤养分和促进根系养分吸收利用[89]。可通过以下2个方面影响氮吸收利用率,一方面,增加根际固氮和铵化等微生物的量可增加土壤养分有效性,促进水稻对氮素的吸收。氮素吸收利用效率高的水稻品种根际富集较多参与铵化等氮代谢相关的微生物,根际中接种这些人工微生物群落可促进土壤中的有机氮转化为铵态氮,显著提高水稻氮素吸收利用率[67];另一方面,降低根际硝化/反硝化微生物的活性可降低土壤氮损失,提高作物氮素吸收利用率。目前,生产上常用不同种类的硝化抑制剂抑制根际氨氧化细菌和氨氧化古菌等硝化细菌的活性,在减少农田氮损失的同时提高水稻的氮素吸收利用率[89]。优化氮肥施用量可促进固氮和铵化等微生物的生成,而合理的氮肥施用方式（例如化肥配施氨基酸增效剂）可降低根际气单胞菌（反硝化细菌）的活性,提高作物的氮素吸收利用率[90,91,92,93]。因此,充分发掘和利用根际微生物有利于增强土壤肥力和降低养分投入[90],是提高水稻氮素吸收利用率的重要途径。
5 水稻根系生长与氮高效的栽培调控
5.1 氮肥管理
5.2 水分管理
水稻生产灌溉方式主要包括淹灌、干湿交替灌溉、控制灌溉和旱作雨养等。轻度干湿交替灌溉可促进水稻根系深扎,增加总根长、根活跃吸收面积、根活力、根源细胞分裂素浓度和氮同化相关酶活性,提高氮肥利用效率[65,97,99]。与常规淹灌相比,控制灌溉能促进根系深扎,增加根系活力,提高产量、水分和氮的高效吸收利用[100,101]。水稻旱作可促进根系深扎,增加根系干重,然而,也可能导致根系生理活性和呼吸速率下降,有时也可能导致产量降低[102,103]。地膜或秸秆覆盖栽培有利于保水保墒,提高水稻产量和氮素吸收利用率,主要原因有2个,一是提高根区的有机质含量以及微生物群落丰度,水稻根系的氮代谢水平显著增加;二是增加土壤温度,促进根系生长和提高根系活力,从而提高水稻地上部干重和产量[102,103,104]。因此,优化水分管理可促进根系生长,提高根系养分和水分吸收能力,实现水稻高产和氮高效吸收利用[105]。
6 展望
水稻根系特征与产量形成和氮素吸收利用效率的关系一直是研究的热点,然而根系特征影响水稻氮高效吸收利用的生理机制仍不够清楚,可从以下几点着手研究。
6.1 深入研究水稻根系解剖特征与氮吸收利用率的关系及其机理
水稻根系形态特征与土层分布相关研究较多,然而根系解剖特征（如根系通气组织和皮层特征等）与氮素吸收利用率的关系还不是很明确。可以借鉴玉米等作物的相关研究,从研究方法上入手,深入研究水稻根系解剖特征与氮吸收利用率的关系及其机理。
6.2 构建水稻理想根构型
水稻植株地上部的理想株型及其特征在高产优质水稻品种的选育中起重要作用。然而,由于根系研究的滞后和农田土壤的多样性,不同作物理想根构型的内涵有很大不同,通过育种和栽培调控等手段构建水稻理想根构型是未来水稻根系研究的重要内容。
6.3 基于根系代谢成本和根系冗余角度研究水稻氮素高效吸收利用机理
6.4 加强根际微生物与作物氮素吸收利用的研究
根际微生物在作物吸收和利用土壤养分中起重要作用,然而根际微生物在促进作物氮素利用的研究还较少,未来应从土壤氮素的活化和流失等角度继续探索根际微生物影响作物氮素吸收利用的机理,在此基础上提出基于有效利用根际微生物作物栽培技术和育种策略。另外,水稻生产栽培措施（如水分和养分管理）对根系生长发育过程和根系特征形成具有很大影响,如何通过优化水肥管理来调节根系生长发育过程和调控根系形态、解剖生理生化特征来减少根系代谢投入是实现水稻减氮增效的一个重要研究点。
参考文献
Strategies for overcoming low agronomic nitrogen use efficiency in irrigated rice systems in China
DOI:10.1016/j.fcr.2005.05.004 URL [本文引用: 2]
Pursuing sustainable productivity with millions of smallholder farmers
DOI:10.1038/nature25785 URL [本文引用: 1]
Addressing agricultural nitrogen losses in a changing climate
DOI:10.1038/s41893-018-0106-0 URL [本文引用: 2]
Exploring optimal nitrogen management strategies to mitigate nitrogen losses from paddy soil in the middle reaches of the Yangtze River
DOI:10.1016/j.agwat.2019.105877 URL [本文引用: 1]
Evolutionary history resolves global organization of root functional traits
DOI:10.1038/nature25783 URL [本文引用: 1]
Low nitrogen enhances nitrogen use efficiency by triggering NO3- uptake and its long-distance translocation
DOI:10.1021/acs.jafc.9b02491 URL [本文引用: 4]
Root genetic research,an opportunity and challenge to rice improvement
DOI:10.1016/j.fcr.2014.04.013 URL [本文引用: 2]
Root phenotypes for improved nutrient capture:an underexploited opportunity for global agriculture
DOI:10.1111/nph.2019.223.issue-2 URL [本文引用: 5]
A better root morpho-physiology after heading contributing to yield superiority of japonica/indica hybrid rice
DOI:10.1016/j.fcr.2018.08.024 URL [本文引用: 1]
Different characteristics of nutrient absorption and utilization between inbred japonica super rice and inter-sub-specific hybrid super rice
DOI:10.1016/j.fcr.2018.01.012 URL [本文引用: 1]
Root and shoot traits for rice varieties with higher grain yield and higher nitrogen use efficiency at lower nitrogen rates application
DOI:10.1016/j.fcr.2015.02.007 URL [本文引用: 1]
Higher nitrogen use efficiency (NUE) in hybrid "super rice" links to improved morphological and physiological traits in seedling roots
DOI:S0176-1617(20)30081-X
PMID:32585498
[本文引用: 2]
Great progress has been achieved in developing hybrid "super rice" varieties in China. Understanding morphological root traits in super rice and the mechanisms of nitrogen acquisition by the root system are of fundamental importance to developing proper fertilisation and nutrient management practices in their production. The present study was designed to study morphological and physiological traits in hybrid super rice roots that are associated with nitrogen use efficiency (NUE). Two hybrid super rice varieties (Yongyou12, YY; Jiayou 6, JY) and one common variety (Xiushui 134, XS) with differing NUE were cultivated hydroponically, and morphological and physiological traits of seedling roots in response to varying nitrogen conditions were investigated. Our results show that the hybrid cultivars YY and JY exhibit larger root systems, arising from a maximisation of root tips and from longer roots without changes in root diameter. The cross-sectional proportion of aerenchyma was significantly higher in super rice roots. The larger root system of super hybrid rice contributed to higher N accumulation and resulted in higher N uptake efficiency. N (NH) labeling results show that YY and JY had an enhanced capacity for ammonium (NH) uptake. Moreover, YY and JY were more tolerant to high NH and showed reduced futile NH efflux. NH efflux in the root elongation zone, measured by Non-invasive Micro-test Technology, was significantly lower than in XS. Taken together, our results suggest that a longer root, a larger number of tips, a better developed aerenchyma, a higher capacity for N uptake, and reduced NH efflux from roots are associated with higher NUE and growth performance in hybrid super rice.Copyright © 2020 Elsevier GmbH. All rights reserved.
水稻产量对氮肥响应的品种间差异及其与根系形态生理的关系
DOI:10.3724/SP.J.1006.2014.01999
[本文引用: 1]
以籼稻天优华占、两优培九和粳稻陵香优18、宁粳1号为材料,研究了水稻产量对氮肥的响应。结果表明,水稻产量对施氮量的反应存在明显的品种间差异。上述4个水稻品种在获得最高产量(10.1~10.3 t hm<sup>-2</sup>)时,天优华占和陵香优18所需施氮量为242.5~255.5 kg hm<sup>-2</sup>,明显低于两优培九和宁粳1号的327.3~328.0 kg hm<sup>-2</sup>。天优华占和陵香优18的氮肥农学利用率和氮肥偏生产力均明显高于两优培九和宁粳1号,表明天优华占和陵香优18产量对氮肥的反应较两优培九和宁粳1号敏感。在高产(10.5~10.9 t hm<sup>-2</sup>)条件下,天优华占和陵香优18主要生育期根系的重量、长度和总吸收表面积低于两优培九和宁粳1号,而根系活跃吸收表面积及其占总吸收表面积的比例、根系伤流量以及根系活力则显著高于两优培九和宁粳1号。上述结果表明,通过栽培措施调控或选用根系活跃吸收表面积、根系伤流量和根系活力高的水稻品种将更有利于降低水稻施氮量和提高产量及氮肥利用效率。
Effects of nitrate on the growth of lateral root and nitrogen absorption in rice
Nitrate regulation of lateral root and root hair development in plants
DOI:10.1093/jxb/erz536 URL [本文引用: 1]
The optimal lateral root branching density for maize depends on nitrogen and phosphorus availability
DOI:10.1104/pp.113.233916 URL [本文引用: 1]
The efficiency of Arabidopsis thaliana (Brassicaceae) root hairs in phosphorus acquisition
Arabidopsis thaliana root hairs grow longer and denser in response to low-phosphorus availability. In addition, plants with the root hair response acquire more phosphorus than mutants that have root hairs that do not respond to phosphorus limiting conditions. The purpose of this experiment was to determine the efficiency of root hairs in phosphorus acquisition at high- and low-phosphorus availability. Root hair growth, root growth, root respiration, plant phosphorus uptake, and plant phosphorus content of 3-wk-old wild-type Arabidopsis (WS) were compared to two root hair mutants (rhd6 and rhd2) under high (54 mmol/m) and low (0.4 mmol/m) phosphorus availability. A cost-benefit analysis was constructed from the measurements to determine root hair efficiency. Under high-phosphorus availability, root hairs did not have an effect on any of the parameters measured. Under low-phosphorus availability, wild-type Arabidopsis had greater total root surface area, shoot biomass, phosphorus per root length, and specific phosphorus uptake. The cost-benefit analysis shows that under low phosphorus, wild-type roots acquire more phosphorus for every unit of carbon respired or unit of phosphorus invested into the roots than the mutants. We conclude that the response of root hairs to low-phosphorus availability is an efficient strategy for phosphorus acquisition.
Superior root hair formation confers root efficiency in some,but not all,rice genotypes upon P deficiency
Effects of root hair length on potassium acquisition in rice (Oryza sativa L.)
DOI:10.15666/aeer URL [本文引用: 1]
Control of root system architecture by DEEPER ROOTING 1 increases rice yield under drought conditions
DOI:10.1038/ng.2725 URL [本文引用: 1]
Digging deeper for agricultural resources,the value of deep rooting
DOI:S1360-1385(19)30332-2
PMID:31964602
[本文引用: 1]
In the quest for sustainable intensification of crop production, we discuss the option of extending the root depth of crops to increase the volume of soil exploited by their root systems. We discuss the evidence that deeper rooting can be obtained by appropriate choice of crop species, by plant breeding, or crop management and its potential contributions to production and sustainable development goals. Many studies highlight the potentials of deeper rooting, but we evaluate its contributions to sustainable intensification of crop production, the causes of the limited research into deep rooting of crops, and the research priorities to fill the knowledge gaps.Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.
Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields
DOI:10.1038/srep05563 URL [本文引用: 2]
Root transcriptomic analysis revealing the importance of energy metabolism to the development of deep roots in rice (Oryza sativa L.)
DOI:10.3389/fpls.2017.01314 URL [本文引用: 1]
Drought-induced root aerenchyma formation restricts water uptake in rice seedlings supplied with nitrate
DOI:10.1093/pcp/pcs003 URL [本文引用: 2]
Radial transport of nutrients:the plant root as a polarized epithelium
DOI:10.1104/pp.114.246124
PMID:25136061
[本文引用: 1]
In higher plants, roots acquire water and soil nutrients and transport them upward to their aerial parts. These functions are closely related to their anatomical structure; water and nutrients entering the root first move radially through several concentric layers of the epidermis, cortex, and endodermis before entering the central cylinder. The endodermis is the innermost cortical cell layer that features rings of hydrophobic cell wall material called the Casparian strips, which functionally resemble tight junctions in animal epithelia. Nutrient uptake from the soil can occur through three different routes that can be interconnected in various ways: the apoplastic route (through the cell wall), the symplastic route (through cellular connections), and a coupled trans-cellular route (involving polarized influx and efflux carriers). This Update presents recent advances in the radial transport of nutrients highlighting the coupled trans-cellular pathway and the roles played by the endodermis as a barrier. © 2014 American Society of Plant Biologists. All Rights Reserved.
Does morphological and anatomical plasticity during the vegetative stage make wheat more tolerant of water-deficit stress than rice?
DOI:10.1104/pp.114.253328 URL [本文引用: 1]
Fine root tradeoffs between nitrogen concentration and xylem vessel traits preclude unified whole-plant resource strategies in Helianthus
DOI:10.1002/ece3.2016.6.issue-4 URL [本文引用: 1]
The nutrient absorption-transportation hypothesis:optimizing structural traits in absorptive roots
DOI:10.1111/nph.2017.213.issue-4 URL [本文引用: 1]
Evolution of US maize (Zea mays L.) root architectural and anatomical phenes over the past 100 years corresponds to increased tolerance of nitrogen stress
DOI:10.1093/jxb/erv074 URL [本文引用: 1]
Large root cortical cell size improves drought tolerance in maize
DOI:10.1104/pp.114.250449
PMID:25293960
[本文引用: 2]
The objective of this study was to test the hypothesis that large cortical cell size (CCS) would improve drought tolerance by reducing root metabolic costs. Maize (Zea mays) lines contrasting in root CCS measured as cross-sectional area were grown under well-watered and water-stressed conditions in greenhouse mesocosms and in the field in the United States and Malawi. CCS varied among genotypes, ranging from 101 to 533 µm(2). In mesocosms, large CCS reduced respiration per unit of root length by 59%. Under water stress in mesocosms, lines with large CCS had between 21% and 27% deeper rooting (depth above which 95% of total root length is located in the soil profile), 50% greater stomatal conductance, 59% greater leaf CO2 assimilation, and between 34% and 44% greater shoot biomass than lines with small CCS. Under water stress in the field, lines with large CCS had between 32% and 41% deeper rooting (depth above which 95% of total root length is located in the soil profile), 32% lighter stem water isotopic ratio of (18)O to (16)O signature, signifying deeper water capture, between 22% and 30% greater leaf relative water content, between 51% and 100% greater shoot biomass at flowering, and between 99% and 145% greater yield than lines with small cells. Our results are consistent with the hypothesis that large CCS improves drought tolerance by reducing the metabolic cost of soil exploration, enabling deeper soil exploration, greater water acquisition, and improved growth and yield under water stress. These results, coupled with the substantial genetic variation for CCS in diverse maize germplasm, suggest that CCS merits attention as a potential breeding target to improve the drought tolerance of maize and possibly other cereal crops. © 2014 American Society of Plant Biologists. All Rights Reserved.
Reduced root cortical cell file number improves drought tolerance in maize
DOI:10.1104/pp.114.249037
PMID:25355868
[本文引用: 2]
We tested the hypothesis that reduced root cortical cell file number (CCFN) would improve drought tolerance in maize (Zea mays) by reducing the metabolic costs of soil exploration. Maize genotypes with contrasting CCFN were grown under well-watered and water-stressed conditions in greenhouse mesocosms and in the field in the United States and Malawi. CCFN ranged from six to 19 among maize genotypes. In mesocosms, reduced CCFN was correlated with 57% reduction of root respiration per unit of root length. Under water stress in the mesocosms, genotypes with reduced CCFN had between 15% and 60% deeper rooting, 78% greater stomatal conductance, 36% greater leaf CO2 assimilation, and between 52% to 139% greater shoot biomass than genotypes with many cell files. Under water stress in the field, genotypes with reduced CCFN had between 33% and 40% deeper rooting, 28% lighter stem water oxygen isotope enrichment (δ(18)O) signature signifying deeper water capture, between 10% and 35% greater leaf relative water content, between 35% and 70% greater shoot biomass at flowering, and between 33% and 114% greater yield than genotypes with many cell files. These results support the hypothesis that reduced CCFN improves drought tolerance by reducing the metabolic costs of soil exploration, enabling deeper soil exploration, greater water acquisition, and improved growth and yield under water stress. The large genetic variation for CCFN in maize germplasm suggests that CCFN merits attention as a breeding target to improve the drought tolerance of maize and possibly other cereal crops. © 2014 American Society of Plant Biologists. All Rights Reserved.
Reduced root cortical burden improves growth and grain yield under low phosphorus availability in maize
DOI:10.1111/pce.v41.7 URL [本文引用: 1]
Root anatomical traits contribute to deeper rooting of maize under compacted field conditions
DOI:10.1093/jxb/eraa165
PMID:32420593
[本文引用: 2]
To better understand the role of root anatomy in regulating plant adaptation to soil mechanical impedance, 12 maize lines were evaluated in two soils with and without compaction treatments under field conditions. Penetrometer resistance was 1-2 MPa greater in the surface 30 cm of the compacted plots at a water content of 17-20% (v/v). Root thickening in response to compaction varied among genotypes and was negatively associated with rooting depth at one field site under non-compacted plots. Thickening was not associated with rooting depth on compacted plots. Genotypic variation in root anatomy was related to rooting depth. Deeper-rooting plants were associated with reduced cortical cell file number in combination with greater mid cortical cell area for node 3 roots. For node 4, roots with increased aerenchyma were deeper roots. A greater influence of anatomy on rooting depth was observed for the thinner root classes. We found no evidence that root thickening is related to deeper rooting in compacted soil; however, anatomical traits are important, especially for thinner root classes.© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.
Enhancement of porosity and aerenchyma formation in nitrogen-deficient rice roots
DOI:10.1016/j.plantsci.2013.10.016 URL [本文引用: 2]
Aerenchyma and barrier to radial oxygen loss are formed in roots of Taro (Colocasia esculenta) propagules under flooded conditions
DOI:10.1007/s10265-019-01150-6 URL [本文引用: 2]
Root strategies for phosphorus acquisition
Root cortical aerenchyma enhances nitrogen acquisition from low-nitrogen soils in maize
DOI:10.1104/pp.114.241711
PMID:24891611
[本文引用: 2]
Suboptimal nitrogen (N) availability is a primary constraint for crop production in developing nations, while in rich nations, intensive N fertilization carries substantial environmental and economic costs. Therefore, understanding root phenes that enhance N acquisition is of considerable importance. Structural-functional modeling predicts that root cortical aerenchyma (RCA) could improve N acquisition in maize (Zea mays). We evaluated the utility of RCA for N acquisition by physiological comparison of maize recombinant inbred lines contrasting in RCA grown under suboptimal and adequate N availability in greenhouse mesocosms and in the field in the United States and South Africa. N stress increased RCA formation by 200% in mesocosms and by 90% to 100% in the field. RCA formation substantially reduced root respiration and root N content. Under low-N conditions, RCA formation increased rooting depth by 15% to 31%, increased leaf N content by 28% to 81%, increased leaf chlorophyll content by 22%, increased leaf CO2 assimilation by 22%, increased vegetative biomass by 31% to 66%, and increased grain yield by 58%. Our results are consistent with the hypothesis that RCA improves plant growth under N-limiting conditions by decreasing root metabolic costs, thereby enhancing soil exploration and N acquisition in deep soil strata. Although potential fitness tradeoffs of RCA formation are poorly understood, increased RCA formation appears be a promising breeding target for enhancing crop N acquisition. © 2014 American Society of Plant Biologists. All Rights Reserved.
Root cortical aerenchyma enhances the growth of maize on soils with suboptimal availability of nitrogen,phosphorus,and potassium
DOI:10.1104/pp.111.175489 URL [本文引用: 1]
Roles of root aerenchyma development and its associated QTL in dry matter production under transient moisture stress in rice
DOI:10.1626/pps.16.205 URL [本文引用: 1]
The role of root apoplastic transport barriers in salt tolerance of rice (Oryza sativa L.)
DOI:10.1007/s00425-009-0930-6
PMID:19363620
[本文引用: 2]
Increasing soil salinity reduces crop yields worldwide, with rice being particularly affected. We have examined the correlation between apoplastic barrier formation in roots, Na+ uptake into shoots and plant survival for three rice (Oryza sativa L.) cultivars of varying salt sensitivity: the salt-tolerant Pokkali, moderately tolerant Jaya and sensitive IR20. Rice plants grown hydroponically or in soil for 1 month were subjected to both severe and moderate salinity stress. Apoplastic barriers in roots were visualized using fluorescence microscopy and their chemical composition determined by gas chromatography and mass spectrometry. Na+ content was estimated by flame photometry. Suberization of apoplastic barriers in roots of Pokkali was the most extensive of the three cultivars, while Na+ accumulation in the shoots was the least. Saline stress induced the strengthening of these barriers in both sensitive and tolerant cultivars, with increase in mRNAs encoding suberin biosynthetic enzymes being detectable within 30 min of stress. Enhanced barriers were detected after several days of moderate stress. Overall, more extensive apoplastic barriers in roots correlated with reduced Na+ uptake and enhanced survival when challenged with high salinity.
Effects of root morphology and anatomy on cadmium uptake and translocation in rice (Oryza sativa L.)
DOI:10.1016/j.jes.2018.04.005 URL [本文引用: 1]
Nitrogen depletion enhances endodermal suberization without restricting transporter-mediated root NO3- influx
DOI:10.1016/j.jplph.2020.153334
PMID:33373827
[本文引用: 1]
Roots vary their permeability to aid radial transport of solutes towards xylem vessels in response to nutritional cues. Nitrogen (N) depletion was previously shown to induce early suberization of endodermal cell walls and reduce hydraulic conductivity of barley roots suggesting reduced apoplastic transport of ions (Armand et al., 2019). Suberization may also limit transcellular ion movement by blocking access to transporters (Barberon et al., 2016). The aim of this study was to confirm that N depletion induced suberization in the roots of barley and demonstrate that this was a specific effect in response to NO depletion. Furthermore, in roots with early and enhanced suberization, we assessed their ability for transporter-mediated NO influx. N depletion induced lateral root elongation and early and enhanced endodermal suberization of the seminal root of each genotype. Both root to shoot NO translocation and net N uptake was half that of plants supplied with steady-state NO. Genes with predicted functions in suberin synthesis (HvHORST) and NO transport (HvNRT2.2) were induced under N-deplete conditions. N-deplete roots had a higher capacity for high-affinity NO influx in early suberized roots than under optimal NO. In conclusion, NO depletion induced early and enhanced suberization in the roots of barley, however, suberization did not restrict transcellular NO transport.Copyright © 2020 Elsevier GmbH. All rights reserved.
Some accessions of amazonian wild rice (Oryza glumaepatula) constitutively form a barrier to radial oxygen loss along adventitious roots under aerated conditions
DOI:10.3390/plants9070880 URL [本文引用: 1]
Ammonium-induced architectural and anatomical changes with altered suberin and lignin levels significantly change water and solute permeabilities of rice (Oryza sativa L.) roots
DOI:10.1007/s00425-015-2406-1
PMID:26384983
[本文引用: 3]
Non-optimal ammonium levels significantly alter root architecture, anatomy and root permeabilities for water and nutrient ions. Higher ammonium levels induced strong apoplastic barriers whereas it was opposite for lower levels. Application of nitrogen fertilizer increases crop productivity. However, non-optimal applications can have negative effects on plant growth and development. In this study, we investigated how different levels of ammonium (NH4 (+)) [low (30 or 100 μM) or optimum (300 μM) or high (1000 or 3000 μM)] affect physio-chemical properties of 1-month-old, hydroponically grown rice roots. Different NH4 (+) treatments markedly altered the root architecture and anatomy. Plants grown in low NH4 (+) had the longest roots with a weak deposition of suberised and lignified apoplastic barriers, and it was opposite for plants grown in high NH4 (+). The relative expression levels of selected suberin and lignin biosynthesis candidate genes, determined using qRT-PCR, were lowest in the roots from low NH4 (+), whereas, they were highest for those grown in high NH4 (+). This was reflected by the suberin and lignin contents, and was significantly lower in roots from low NH4 (+) resulting in greater hydraulic conductivity (Lp r) and solute permeability (P sr) than roots from optimum NH4 (+). In contrast, roots grown at high NH4 (+) had markedly greater suberin and lignin contents, which were reflected by strong barriers. These barriers significantly decreased the P sr of roots but failed to reduce the Lp r below those of roots grown in optimum NH4 (+), which can be explained in terms of the physical properties of the molecules used and the size of pores in the apoplast. It is concluded that, in rice, non-optimal NH4 (+) levels differentially affected root properties including Lp r and P sr to successfully adapt to the changing root environment.
Adaption of roots to nitrogen deficiency revealed by 3D quantification and proteomic analysis
DOI:10.1104/pp.18.00716
PMID:30455286
[本文引用: 1]
Rapeseed () is an important oil crop worldwide. However, severe inhibition of rapeseed production often occurs in the field due to nitrogen (N) deficiency. The root system is the main organ to acquire N for plant growth, but little is known about the mechanisms underlying rapeseed root adaptions to N deficiency. Here, dynamic changes in root architectural traits of N-deficient rapeseed plants were evaluated by 3D in situ quantification. Root proteome responses to N deficiency were analyzed by the tandem mass tag-based proteomics method, and related proteins were characterized further. Under N deficiency, rapeseed roots become longer, with denser cells in the meristematic zone and larger cells in the elongation zone of root tips, and also become softer with reduced solidity. A total of 171 and 755 differentially expressed proteins were identified in short- and long-term N-deficient roots, respectively. The abundance of proteins involved in cell wall organization or biogenesis was highly enhanced, but most identified peroxidases were reduced in the N-deficient roots. Notably, peroxidase activities also were decreased, which might promote root elongation while lowering the solidity of N-deficient roots. These results were consistent with the cell wall components measured in the N-deficient roots. Further functional analysis using transgenic Arabidopsis () plants demonstrated that the two root-related differentially expressed proteins contribute to the enhanced root growth under N deficiency conditions. These results provide insights into the global changes of rapeseed root responses to N deficiency and may facilitate the development of rapeseed cultivars with high N use efficiency through root-based genetic improvements.© 2019 American Society of Plant Biologists. All Rights Reserved.
AMT1;1 transgenic rice plants with enhanced NH4+ permeability show superior growth and higher yield under optimal and suboptimal NH4+ conditions
DOI:10.1093/jxb/ert458
PMID:24420570
[本文引用: 2]
The major source of nitrogen for rice (Oryza sativa L.) is ammonium (NH4(+)). The NH4(+) uptake of roots is mainly governed by membrane transporters, with OsAMT1;1 being a prominent member of the OsAMT1 gene family that is known to be involved in NH4(+) transport in rice plants. However, little is known about its involvement in NH4(+) uptake in rice roots and subsequent effects on NH4(+) assimilation. This study shows that OsAMT1;1 is a constitutively expressed, nitrogen-responsive gene, and its protein product is localized in the plasma membrane. Its expression level is under the control of circadian rhythm. Transgenic rice lines (L-2 and L-3) overexpressing the OsAMT1;1 gene had the same root structure as the wild type (WT). However, they had 2-fold greater NH4(+) permeability than the WT, whereas OsAMT1;1 gene expression was 20-fold higher than in the WT. Analogous to the expression, transgenic lines had a higher NH4(+) content in the shoots and roots than the WT. Direct NH4(+) fluxes in the xylem showed that the transgenic lines had significantly greater uptake rates than the WT. Higher NH4(+) contents also promoted higher expression levels of genes in the nitrogen assimilation pathway, resulting in greater nitrogen assimilates, chlorophyll, starch, sugars, and grain yield in transgenic lines than in the WT under suboptimal and optimal nitrogen conditions. OsAMT1;1 also enhanced overall plant growth, especially under suboptimal NH4(+) levels. These results suggest that OsAMT1;1 has the potential for improving nitrogen use efficiency, plant growth, and grain yield under both suboptimal and optimal nitrogen fertilizer conditions.
Expression of the nitrate transporter gene OsNRT1.1A/OsNPF6.3 confers high yield and early maturation in rice
DOI:10.1105/tpc.17.00809
PMID:29475937
[本文引用: 1]
Nitrogen (N) is a major driving force for crop yield improvement, but application of high levels of N delays flowering, prolonging maturation and thus increasing the risk of yield losses. Therefore, traits that enable utilization of high levels of N without delaying maturation will be highly desirable for crop breeding. Here, we show that OsNRT1.1A (OsNPF6.3), a member of the rice () nitrate transporter 1/peptide transporter family, is involved in regulating N utilization and flowering, providing a target to produce high yield and early maturation simultaneously. has functionally diverged from previously reported genes in plants and functions in upregulating the expression of N utilization-related genes not only for nitrate but also for ammonium, as well as flowering-related genes. Relative to the wild type, mutants exhibited reduced N utilization and late flowering. By contrast, overexpression of in rice greatly improved N utilization and grain yield, and maturation time was also significantly shortened. These effects were further confirmed in different rice backgrounds and also in Our study paves a path for the use of a single gene to dramatically increase yield and shorten maturation time for crops, outcomes that promise to substantially increase world food security.© 2018 American Society of Plant Biologists. All rights reserved.
NRT1.1B is associated with root microbiota composition and nitrogen use in field-grown rice
DOI:10.1038/s41587-019-0104-4 URL [本文引用: 2]
Variation in NRT1.1B contributes to nitrate-use divergence between rice subspecies
Hu, Bin; Wang, Wei; Ou, Shujun; Tang, Jiuyou; Li, Hua; Che, Ronghui; Zhang, Zhihua; Wang, Hongru; Wang, Yiqin; Liang, Chengzhen; Xu, Chi; Liang, Yan; Chu, Chengcai Chinese Acad Sci, Inst Genet & Dev Biol, Natl Ctr Plant Gene Res Beijing, State Key Lab Plant Gen, Beijing, Peoples R China. Wang, Wei; Li, Hua; Zhang, Zhihua; Wang, Hongru; Liang, Yan Univ Chinese Acad Sci, Coll Life Sci, Beijing, Peoples R China. Ou, Shujun Michigan State Univ, Dept Hort, E Lansing, MI 48824 USA. Chai, Xuyang Capital Normal Univ, Coll Life Sci, Beijing, Peoples R China. Liu, Linchuan Chinese Acad Sci, Shanghai Ctr Plant Stress Biol, Shanghai, Peoples R China. Piao, Zhongze Shanghai Acad Agr Sci, Crop Breeding & Cultivat Res Inst, Shanghai, Peoples R China. Deng, Qiyun China Natl Hybrid Rice Res, Changsha, Peoples R China. Deng, Qiyun Dev Ctr, Changsha, Peoples R China. Deng, Kun; Zhang, Lianhe Henan Univ Sci & Technol, Sch Agr, Luoyang, Peoples R China.
Plant nitrate transporters:from gene function to application
DOI:10.1093/jxb/erx011 URL [本文引用: 1]
Nitrogen use efficiency is mediated by vacuolar nitrate sequestration capacity in roots of Brassica napus
DOI:10.1104/pp.15.01377 URL [本文引用: 1]
Knock-down of a tonoplast localized low-affinity nitrate transporter OsNPF7.2 affects rice growth under high nitrate supply
Genome-wide associated study identifies NAC42-activated nitrate transporter conferring high nitrogen use efficiency in rice
DOI:10.1038/s41467-019-13187-1 URL [本文引用: 1]
Amino acid export in plants:a missing link in nitrogen cycling
DOI:10.1093/mp/ssr003
PMID:21324969
[本文引用: 1]
The export of nutrients from source organs to parts of the body where they are required (e.g. sink organs) is a fundamental biological process. Export of amino acids, one of the most abundant nitrogen species in plant long-distance transport tissues (i.e. xylem and phloem), is an essential process for the proper distribution of nitrogen in the plant. Physiological studies have detected the presence of multiple amino acid export systems in plant cell membranes. Yet, surprisingly little is known about the molecular identity of amino acid exporters, partially due to the technical difficulties hampering the identification of exporter proteins. In this short review, we will summarize our current knowledge about amino acid export systems in plants. Several studies have described plant amino acid transporters capable of bi-directional, facilitative transport, reminiscent of activities identified by earlier physiological studies. Moreover, recent expansion in the number of available amino acid transporter sequences have revealed evolutionary relationships between amino acid exporters from other organisms with a number of uncharacterized plant proteins, some of which might also function as amino acid exporters. In addition, genes that may regulate export of amino acids have been discovered. Studies of these putative transporter and regulator proteins may help in understanding the elusive molecular mechanisms of amino acid export in plants.
Preanthesis root growth and nitrogen uptake improved wheat grain yield and nitrogen use efficiency
DOI:10.2134/agronj2019.03.0162 URL [本文引用: 1]
Real time visualization of 13N-translocation in rice under different environmental conditions using positron emitting tracer imaging system
The ammonium ion is an indispensable nitrogen source for crops, especially paddy rice (Oryza sativa L. cv Nipponbare). Until now, it has been impossible to measure ammonium uptake and nitrogen movement in plants in real time. Using the new technologies of PETIS (positron emitting tracer imaging system) and PMPS (positron multi-probe system), we were able to visualize the real time translocation of nitrogen and water in rice plants. We used positron-emitting 13N-labeled ammonium (13NH4+) and 15O-water to monitor the movement. In plants cultured under normal conditions, 13NH4+ supplied to roots was taken up, and a 13N signal was detected at the discrimination center, the basal part of the shoots, within 2 minutes. This rapid translocation of (13)N was almost completely inhibited by a glutamine synthetase inhibitor, methionine sulfoximine. In general, nitrogen deficiency enhanced 13N translocation to the discrimination center. In the dark, 13N translocation to the discrimination center was suppressed to 40% of control levels, whereas 15O-water flow from the root to the discrimination center stopped completely in the dark. In abscisic acid-treated rice, 13N translocation to the discrimination center was doubled, whereas translocation to leaves decreased to 40% of control levels. Pretreatment with NO3- for 36 hours increased 13N translocation from the roots to the discrimination center to 5 times of control levels. These results suggest that ammonium assimilation (from the roots to the discrimination center) depends passively on water flow, but actively on NH4+-transporter(s) or glutamine synthetase(s).
Cytosolic glutamine synthetase1;2 is responsible for the primary assimilation of ammonium in rice roots
DOI:10.1093/pcp/pct046 URL [本文引用: 2]
The stable level of glutamine synthetase 2 plays an important role in rice growth and in carbon-nitrogen metabolic balance
DOI:10.3390/ijms160612713 URL [本文引用: 1]
Concurrent activation of OsAMT1;2 and OsGOGAT1 in rice leads to enhanced nitrogen use efficiency under nitrogen limitation
DOI:10.1111/tpj.v103.1 URL [本文引用: 1]
The indica nitrate reductase gene OsNR2 allele enhances rice yield potential and nitrogen use efficiency
DOI:10.1038/s41467-019-13110-8 URL [本文引用: 1]
Metabolic adaptations of plant respiration to nutritional phosphate deprivation
Plants respond adaptively to orthophosphate (Pi) deprivation through the induction of alternative pathways of glycolysis and mitochondrial electron transport. These respiratory bypasses allow respiration to proceed in Pi-deficient plant cells because they negate the necessity for adenylates and Pi, both pools of which are severely depressed following nutritional Pi starvation.
Alternative respiration pathways and secondary metabolism in plants with different adaptive strategies under mineral deficiency
DOI:10.1023/A:1022973130775 URL [本文引用: 3]
Root exudates:from plant to rhizosphere and beyond
DOI:10.1007/s00299-019-02447-5 URL [本文引用: 2]
Plant nitrogen nutrition:sensing and signaling
DOI:S1369-5266(16)30216-3
PMID:28614749
[本文引用: 1]
In response to external fluctuations of nitrogen (N) supplies, plants can activate complex regulatory networks for optimizing N uptake and utilization. In this review, we highlight novel N-responsive sensors, transporters, and signaling molecules recently identified in the dicot Arabidopsis and the monocot rice, and discuss their potential roles in N sensing and signaling. Furthermore, over the last couple of years, N sensing has been shown to be affected by multiple external factors, which act as local signals to trigger systemic signaling coordinated by long-distance mobile signals. Understanding of this complex regulatory network provides a foundation for the development of novel strategies to increase the root N acquisition efficiency under varying N conditions for crop production.Copyright © 2017 Elsevier Ltd. All rights reserved.
Biological nitrification inhibition by rice root exudates and its relationship with nitrogen-use efficiency
DOI:10.1111/nph.14057
PMID:27292630
[本文引用: 1]
Microbial nitrification in soils is a major contributor to nitrogen (N) loss in agricultural systems. Some plants can secrete organic substances that act as biological nitrification inhibitors (BNIs), and a small number of BNIs have been identified and characterized. However, virtually no research has focused on the important food crop, rice (Oryza sativa). Here, 19 rice varieties were explored for BNI potential on the key nitrifying bacterium Nitrosomonas europaea. Exudates from both indica and japonica genotypes were found to possess strong BNI potential. Older seedlings had higher BNI abilities than younger ones; Zhongjiu25 (ZJ25) and Wuyunjing7 (WYJ7) were the most effective genotypes among indica and japonica varieties, respectively. A new nitrification inhibitor, 1,9-decanediol, was identified, shown to block the ammonia monooxygenase (AMO) pathway of ammonia oxidation and to possess an 80% effective dose (ED ) of 90 ng μl. Plant N-use efficiency (NUE) was determined using a N-labeling method. Correlation analyses indicated that both BNI abilities and 1,9-decanediol amounts of root exudates were positively correlated with plant ammonium-use efficiency and ammonium preference. These findings provide important new insights into the plant-bacterial interactions involved in the soil N cycle, and improve our understanding of the BNI capacity of rice in the context of NUE.© 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.
Root-associated microbiomes of wheat under the combined effect of plant development and nitrogen fertilization
DOI:10.1186/s40168-019-0750-2 URL [本文引用: 2]
根际微生物促进水稻氮利用的机制
DOI:10.11983/CBB19060
[本文引用: 1]
根际微生物影响植物的生长及环境适应性。不同种属、不同种群的植物影响其环境微生物群落; 反之, 根际微生物也影响宿主植物生长发育与生态适应性。植物与根际微生物的互作现象及其机制, 是生命科学研究关注的热点, 也是农业微生物利用的关键问题。近期, 中国科学家在该领域取得了突破性进展。通过对不同籼稻(Oryza sativa subsp. indica)和粳稻(O. sativa subsp. japonica)品种的根际微生物组进行研究, 发现籼稻根际比粳稻根际富集更多参与氮代谢的微生物群落, 且该现象与硝酸盐转运蛋白基因NRT1.1B在籼粳之间的自然变异相关联。通过对籼稻接种籼稻根际特异富集的微生物群体可以提高前者对有机氮的利用, 促进其生长。该研究揭示了籼稻和粳稻根际微生物分化的分子基础, 展示了利用根际微生物提高水稻营养高效吸收的应用前景。
Rice root growth and nutrient uptake as influenced by organic manure in continuously and alternately flooded paddy soils
DOI:10.1016/j.agwat.2004.05.003 URL [本文引用: 1]
Combination of site-specific nitrogen management and alternate wetting and drying irrigation increases grain yield and nitrogen and water use efficiency in super rice
DOI:10.1016/j.fcr.2013.08.016 URL [本文引用: 2]
The effects of different water and nitrogen managements on yield and nitrogen use efficiency in hybrid rice of China
DOI:10.1016/j.fcr.2011.11.015 URL [本文引用: 2]
Enhancement of root systems improves productivity and sustainability in water saving ground cover rice production system
DOI:10.1016/j.fcr.2017.08.008 URL [本文引用: 1]
Root phenes that reduce the metabolic costs of soil exploration:opportunities for 21st century agriculture
