植物激素响应和调控丛枝菌根共生研究进展

【目的】丛枝菌根是土壤中的丛枝菌真菌（arbuscular mycorrhizal,AM）与大多数陆地植物根系形成的互惠共生体。丛枝菌根的形成过程是一系列信号交换和转导的结果,受到很多基因的程序化表达调控。植物激素作为重要的信号物质被证实能够参与调控植物与AM真菌的互作过程。本文简述了植物激素在调控丛枝菌根形成的作用机理,为激素调控丛枝菌根形成的研究与应用提供理论线索。主要进展外源施加低浓度的生长素和脱落酸能够促进丛枝菌根共生,而外源施加赤霉素能够显著抑制丛枝菌根中丛枝的形成;内源缺失赤霉素,脱落酸以及油菜素内酯会抑制丛枝菌根共生;茉莉酸合成突变体推迟丛枝菌根形成;独脚金内酯合成、转运以及受体突变体都会抑制丛枝菌根共生;生长素以及脱落酸受体表达量降低会抑制丛枝菌根共生。但是生长素信号受体的降低表达不仅能够显著抑制丛枝菌根的形成还能显著抑制丛枝细胞的正常发育,而植物脱落酸信号受体表达降低突变体中丛枝细胞发育正常。研究展望激素如何调控丛枝菌根共生的研究仍处于起步阶段。随着转基因和基因编辑技术（如Crispr/cas9系统介导的基因敲除技术）的快速发展以及通过菌根植物的基因组、转录组、蛋白质和代谢组数据的挖掘,丛枝菌根共生中的众多科学问题以及与其他植物-微生物互作系统等问题都将一一得到解答。     

同位素示踪研究丛枝菌根真菌吸收不同氮素并向寄主植物输运的机理

丛枝菌根(Arbuscular mycorrhizae,AM)是自然界中普遍存在的与植物共生的真菌[1]。目前人们对AM真菌的基础研究主要是着眼于与植物共生的生化代谢机理和信号机制、遗传学、建立共生关系相关基因的研究[2-8]。     

旱作水稻西瓜间丛枝菌根菌丝桥诱导水稻磷转运蛋白的表达及对磷吸收的影响

采用中间隔网的土培根箱试验,对旱作水稻或/和西瓜接种丛枝菌根真菌(简称AM真菌)幼套球囊霉(Glomus etunicatum Becker&Gerdemann),研究了旱作水稻/西瓜间形成菌丝桥并诱导水稻磷酸盐转运蛋白OsPT11的表达和对磷吸收的影响。结果表明:(1)根箱两侧均未接种AM真菌时,旱作水稻和西瓜根系均不形成菌根,水稻根系的磷酸盐转运蛋白OsPT11也不表达。(2)西瓜侧接种AM真菌时,西瓜与水稻间形成的菌丝桥引起水稻菌根的形成,并诱导水稻根系磷酸盐转运蛋白OsPT11表达。(3)菌丝桥侵染和直接接种侵染对旱作水稻和西瓜形成丛枝菌根能达到相同的效果,旱作水稻和西瓜的菌根侵染率分别为80%以上和70%以上。(4)在旱作水稻/西瓜间作系统中,当接种AM真菌时,水稻和西瓜根际有效磷含量显著高于对照处理,水稻地上部全磷含量降低,而西瓜地上部全磷含量升高。     

丛枝菌根(AM)真菌与共生植物物质交换研究进展

丛枝菌根(Arbuscular Mycorrhizal,AM)真菌能与约 80% 的陆生植物形成共生关系,植、 菌间矿质养分、 碳水化合物的物质交换是自然界物质循环的重要内容。目前,AM 真菌促进共生植物矿质养分吸收的研究相对较多。研究表明, AM 真菌可通过根外菌丝更小的吸收直径,加强矿质养分的空间有效性; 通过释放有机酸、 土壤酶,活化土壤中被固定的矿质养分; 通过根外菌丝上较低 Km 值的矿质养分转运蛋白,保证养分从土壤至根外菌丝的转运效率; 通过矿质养分在菌丝内运输形式的改变,增强养分的运输速率; 通过诱导共生植物矿质养分转运蛋白表达,提高植、 菌间养分的转运效率。相较于 AM 真菌促进共生植物养分吸收,植物反馈真菌碳水化合物的研究相对较少。鉴于 AM 真菌与植物共生关系在生态系统中的重要作用,明晰植、 菌间矿质养分和碳水化合物交换的具体场所(丛枝、 根内菌丝、 根外菌丝)、 具体形式(离子、 聚合物、 氨基酸、 蔗糖、 单糖)、 具体过程(主动运输)具有重要科学意义。本文对 AM 真菌与共生植物物质交换的丛枝、 菌丝双膜结构,氮(N)、 磷(P)、 糖等物质交换的具体形式以及跨双膜、 耗能量、 互耦连的物质交换过程进行综述,并从物质交换的场所、 形式、 过程三个方面提出了植、 菌物质交换的研究方向。     

丛枝菌根真菌AMF提高植物抗逆性的组学技术研究进展

  【目的】  丛枝菌根真菌(AMF)可以显著提高植物对逆境胁迫的抵抗能力,本文综述了国内外针对代表性组学技术(转录组学、蛋白质组学和代谢组学)在AMF提高植物抗逆领域(干旱、温度、盐碱、重金属)的研究进展,分析了在逆境胁迫下,植物–菌根共生体在分子层面上的应答调控机理,为深入理解AMF提高植物耐逆的分子机理提供一定的科学依据。  主要进展  植物主要通过根系与AMF建立共生关系,进而从土壤中吸收更多的水分和营养物质,提高植物对非生物胁迫的抵抗能力。菌根植物在转录、翻译以及表观遗传层面应答非生物胁迫。AMF在不同程度上上调或下调某些与非生物胁迫相关基因的转录或蛋白的翻译及降解,从而提高植物对非生物胁迫的抵抗能力,维持植物的生长发育,提高其对水分和营养物质的吸收和利用效率。通过转录组学、蛋白质组学和代谢组学分析关键基因、蛋白及代谢物的变化,为深入挖掘AMF提高植物抗逆机理提供理论依据。  研究展望  揭示丛枝菌根共生体抗逆机理的组学技术研究仍处于起步阶段,单一组学的应用限制了信息表达的完整性和深层次网络调控机理的精确性。随着测序技术和手段在速度、精度等方面的提高以及生物信息学的更新发展,AMF提高植物抗逆性组学的研究将朝着多组学结合的方向发展,使研究者能够从多角度全面探究植物相关研究的分子机理,这有助于更全面地理解植物相关生命活动的分子调控规律。     

丛枝菌根真菌促进植物摄取土壤磷的作用机制

磷在土壤中易被固定沉淀,在植物磷利用率低的情况下,过度施肥会造成磷肥浪费,可能通过地表径流、地下水溶解等方式,造成水体富营养化产生面源污染,对人类生产生活造成较大影响。丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)和植物结合所形成的共生菌根可以显著增强植株对磷的吸收利用。通过AMF可以提高宿主植株对磷的吸收转运的特性,从AMF促进植株对磷元素的摄取机制、AMF促进植物磷摄取分子机理、AMF作用下根系分泌物对植株磷利用的影响与根际微生物对AMF磷元素利用的影响4个方面的研究进展进行分析总结。AMF可以通过改变宿主植株的根系形态和菌丝网络的形成,扩大植株对养分吸收范围;释放有机酸、磷酸酶和质子等根系分泌物改变土壤结构和理化性质,与根际微生物共同作用降解土壤中难溶性磷酸盐;诱导相关磷转运蛋白基因的特异性表达,提高植株对磷的转运能力而促进其吸收。     

不同丛枝菌根真菌(AMF)对茶树生长及耐盐性的影响探究

丛枝菌根真菌是现今陆生植物中广泛存在的共生微生物类型,在同植物共生情况下,将对植物在胁迫环境的存活力产生影响。基于此,探究不同丛枝菌根真菌(AMF)对茶树生长及耐盐性的影响。     

烟草与丛枝菌根真菌的共生效应研究进展

丛枝菌根(Arbuscular mycorrhiza,AM)真菌是陆地生态系统中广泛存在的一类专性共生土壤微生物,是根系土壤区域中重要的功能菌群之一。AM真菌可侵染植物根系形成丛枝菌根共生体,改变植物根系形态和改善营养状况,从而提高宿主植物的生长发育、产量、质量和抗逆性。目前从烟草根系土壤分离报道的AM真菌已达13属54种,显示出烟草(Nicotiana tobacum L.)栽培的潜在AM真菌资源较为丰富。围绕烟草与AM真菌的共生效应,总结了影响AM真菌侵染和定殖烟草根系的主要因素,阐述了AM真菌对烟草生长、抗性生理及品质的影响,并对PGPR与AM真菌的协同作用进行了简要回顾,最后讨论了该领域存在的不足及今后展望;旨在为菌根技术运用于烟草栽培提供参考。     

AM真菌与紫云英Ri T-DNA转化根双重培养体系的建立

丛枝菌根(Arbuscular mycorrhiza,AM)真菌是一类古老的植物共生真菌,与植物约有4亿年共生史,能与80%以上的陆生维管植物形成互惠共生体—丛枝菌根,可以改善植物对磷素营养的吸收,增强植物的抗逆性、抗病力或耐病力,与根瘤菌共同作用于豆科植物促进豆科植物正常的生长发育,提高产量,在自然生态系统和实践应用中发挥着重要作用。     

接种丛枝菌根真菌对小麦根内氮转运蛋白基因表达的影响

通过盆栽试验,研究了在低氮(不施氮)和高氮(施氮0.2 g·kg~(-1))水平下接种不同种类丛枝菌根(AM)真菌[Funneliformis mosseae(BGC-NM03D)、Claroideoglomus etunicatum(BGC-NM01B)和Rhizophagus intraradices(BJ09)]对小麦生长、氮吸收及根内4个硝态氮转运蛋白(NRT)基因、1个辅助蛋白(NAR)基因和2个铵态氮转运蛋白(AMT)基因表达的影响。结果表明,3种AM真菌均能够侵染小麦根系,以R.intraradices菌根的侵染率最高;接种R.intraradices或C.etunicatum能够显著提高小麦的生物量或地上部氮吸收量;无论是高氮还是低氮处理,接种AM真菌后均显著下调了小麦根内NRT、NAR和AMT基因的表达水平,且不同AM真菌调控小麦根内氮转运蛋白基因表达的能力具有明显差异。     

铬稳定同位素在丛枝菌根蒲公英中的分馏及根外菌丝对铬的吸收

As common soil fungi that form symbioses with most terrestrial plants,arbuscular mycorrhizal(AM) fungi play an important role in plant adaptation to chromium(Cr) contamination.However,little information is available on the underlying mechanisms of AM symbiosis on plant Cr resistance.In this study,dandelion(Taraxacum platypecidum Diels.) was grown with and without inoculation of the AM fungus Rhizophagus irregularis and Cr uptake by extraradical mycelium(ERM) was investigated by a compartmented cultivation system using a Cr stable isotope tracer.The results indicated that AM symbiosis increased plant dry weights and P concentrations but decreased shoot Cr concentrations.Using the Cr stable isotope tracer technology,the work provided possible evidences of Cr uptake and transport by ERM,and confirmed the enhancement of root Cr stabilization by AM symbiosis.This study also indicated an enrichment of lighter Cr isotopes in shoots during Cr translocation from roots to shoots in mycorrhizal plants.     

Arbuscular mycorrhizal fungi regulate plant mineral nutrient uptake and partitioning in iron ore tailings undergoing eco-engineered pedogenesis

Excess available K and Fe in Fe ore tailings with organic matter amendment and water-deficiencies may restrain plant colonization and growth, which hinders the formation of eco-engineered soil from these tailings for sustainable and cost-effective mine site rehabilitation. Arbuscular mycorrhizal (AM) fungi are widely demonstrated to assist plant growth under various unfavorable environments. However, it is still unclear whether AM symbiosis in tailings amended with different types of plant biomass and under different water conditions could overcome the surplus K and Fe stress for plants in Fe ore tailings, and if so, by what mechanisms. Here, host plants (Sorghum sp. Hybrid cv. Silk), either colonized or noncolonized by the AM fungi (Glomus spp.), were cultivated in lucerne hay (LH, C:N ratio of 18)- or sugarcane mulch (SM, C:N ratio of 78)-amended Fe ore tailings under well-watered (55% water-holding capacity (WHC) of tailings) or water-deficient (30% WHC of tailings) conditions. Root mycorrhizal colonization, plant growth, and mineral elemental uptake and partitioning were examined. Results indicated that AM fungal colonization improved plant growth in tailings amended with plant biomass under water-deficient conditions. Arbuscular mycorrhizal fungal colonization enhanced plant mineral element uptake, especially P, both in the LH- and SM-amended tailings regardless of water condition. Additionally, AM symbiosis development restrained the translocation of excess elements (i.e., K and Fe) from plant roots to shoots, thereby relieving their phytotoxicity. The AM fungal roles in P uptake and excess elemental partitioning were greater in LH-amended tailings than in SM-amended tailings. Water deficiency weakened AM fungal colonization and functions in terms of mineral element uptake and partitioning. These findings highlighted the vital role AM fungi played in regulating plant growth and nutrition status in Fe ore tailings technosol, providing an important basis for involvement of AM fungi in the eco-engineered pedogenesis of Fe ore tailings.     

一氧化氮在植物发育及植物–微生物互作中的作用机制研究进展

一氧化氮 (NO) 作为高活性信号分子,是调控植物生长发育的关键因子。NO可提高植物对非生物胁迫及生物胁迫的抗性,增强植物的免疫能力。最新的研究表明,NO在植物根系与微生物的互作过程中发挥着重要作用,NO能够促进植物根系与根瘤菌及丛枝菌根真菌形成共生体,从而提高植物对土壤氮磷养分的获取。NO作为信号物质调控植物对生物胁迫和非生物胁迫抗性的主要机制有:1) NO与活性氧系统互作,调节活性氧的水平,缓解氧化应激反应对植物的伤害;2) NO通过蛋白质的翻译后修饰,对植物免疫及抗逆过程进行调节;3) NO与多种植物激素互作,参与激素对植物生长发育的调节过程。而且NO可促进共生体的形成及发育相关基因表达,抑制免疫基因表达,通过NO与植物球蛋白 (phytoglobin) 的循环维持共生体的氧化还原水平及能量状态,从而促进植物–微生物共生关系。以往关于NO的研究主要集中在前3个方面,有关NO在植物–微生物互作中的作用机制的研究较少,NO参与植物–微生物互作机制的研究亟待加强。揭示NO增强植物抗逆性及其调节根系发育的机制,深入探究NO调控植物–微生物互作的机理,对于提高集约化作物生产体系中养分利用效率和作物生产力具有重要的理论与实践意义。     

Arbuscular Mycorrhizal Mediated Nutrition in Plants

ABSTRACT

Arbuscular mycorrhizae (AM) are the symbiotic fungi that predominate in the roots and soils of agricultural crop plants. The most recognized beneficial effect of these fungi is to enhance host plant uptake of relatively immobile nutrients, in particular phosphorus (P), and several micronutrients. The AM fungi absorb inorganic P either from the soluble P pools in the soil, or from insoluble forms such as rock phosphates as well as from insoluble organic sources. Recent studies show that mycorrhizal fungi would have access to rock phosphate through localized alterations of pH and/or by the production of organic acid anions that may act as chelating agents. The AM colonization also improves plant N nutrition. Generally mycorrhizal symbiosis more influences on nitrogen (N) uptake and translocation if ammonium (NH₄ ⁺) rather than nitrate (NO₃ ^?) is the nitrogen source. However, under drought stress the role of mycorrhizae in NO₃ ^? transport to the root surface may be significant as the NO₃ ^? mobility is severely restricted due to its low concentration and diffusion rate under such circumstances. However, as yet little is known about the mechanism of N uptake by the AM fungi. Uptake of micronutrients is also influenced by mycorrhizal colonization.     

细胞膜H+-ATP酶在植物矿质营养中的作用

细胞膜H+-ATP酶是植物体内一类重要的质子泵,也是一种极其关键的转运蛋白,在植物各种生命活动中具有重要的功能。本文综述了细胞膜H+-ATP酶的活性调控机制,及其在植物根系吸收与利用矿质营养中的生理作用。细胞膜H+-ATP酶通过消耗ATP将细胞质中的H+排出,为养分离子的跨膜转运,以及有机酸和生物硝化抑制剂等物质的分泌提供细胞膜电位和质子驱动力。在缺磷、缺铁和铝毒等营养逆境下,细胞膜H+-ATP酶在受诱导后通过分泌H+使根际酸化,从而提高磷和铁的有效性,还通过促进有机酸分泌来活化土壤中的矿物态磷,并且可以降低铝离子的毒害。此外,细胞膜H+-ATP酶还参与调节植物根系的生长以及植物与丛枝菌根真菌的共生。通过遗传途径调节细胞膜H+-ATP酶及其上游调节因子,如蛋白激酶和磷酸酶等基因的表达,以及对细胞膜H+-ATP酶的特定氨基酸位点进行突变,可以改良作物细胞膜H+-ATP酶的活性。这是一种提高作物养分利用效率、增强作物抵抗营养逆境的有效策略。     

Are the rates of photosynthesis stimulated by the carbon sink strength of rhizobial and arbuscular mycorrhizal symbioses?

Rhizobial and arbuscular mycorrhizal (AM) symbioses each may consume 4-16% of recently photosynthetically-fixed carbon to maintain their growth, activity and reserves. Rhizobia and AM fungi improve plant photosynthesis through N and P acquisition, but increased nutrient uptake by these symbionts does not fully explain observed increases in the rate of photosynthesis of symbiotic plants. In this paper, we test the hypothesis that carbon sink strength of rhizobial and AM symbioses stimulates the rates of photosynthesis. Nutrient-independent effects of rhizobial and AM symbioses result in direct compensation of C costs at the source. We calculated the response ratios of photosynthesis and nutrient mass fraction in the leaves of legumes inoculated with rhizobial and/or AM fungi relative to non-inoculated plants in a number of published studies. On average, photosynthetic rates were significantly increased by 28 and 14% due to rhizobial and AM symbioses, respectively, and 51% due to dual symbiosis. The leaf P mass fraction was increased significantly by 13% due to rhizobial symbioses. Although the increases were not significant, AM symbioses increased leaf P mass fraction by 6% and dual symbioses by 41%. The leaf N mass fraction was not significantly affected by any of the rhizobial, AM and dual symbioses. The rate of photosynthesis increased substantially more than the C costs of the rhizobial and AM symbioses. The inoculation of legumes with rhizobia and/or AM fungi, which resulted in sink stimulation of photosynthesis, improved the photosynthetic nutrient use efficiency and the proportion of seed yield in relation to the total plant biomass (harvest index). Sink stimulation represent an adaptation mechanism that allows legumes to take advantage of nutrient supply from their microsymbionts without compromising the total amount of photosynthates available for plant growth.