食根动物与植物的相互关系

食根动物是植物的主要危害者,植物与食根动物之间的相互作用一直备受关注.本文从食根动物与异质性土壤、根系的关系,以及食根动物对植物的影响等方面,探讨了食根动物与根系生物量的变化、再生能力、存活,植物化学物质与其他有机体之间的作用机理和食根动物对植物生理、种群动态、植物结构的影响.建议加强对植物控制食根动物取食时采取的对策、食根动物改变生态系统C、N循环的机制以及植物寄生性线虫存在的生态系统养分的动态变化等方面的研究.     

根黄酮在植物生长和营养中的作用

本文简要综述了８０年代以来国际上对根黄酮在调节植物根生长,完善根功能,影响氮素循环及在施加他感作用方面的研究进展,并对有关方面作了一些展望,以期引起植物营养工作者对植物次生物质的注意。     

植物根际微生物群落构建的研究进展

植物根际是指植物根系与土壤的交界面,是根系自身生命活动和代谢对土壤影响最直接、最强烈的区域,其物理、化学和生物性质不同于土体土壤。在这个区域里,与植物发生相互作用的大量微生物,被称为根际微生物。根际微生物在植物的生长发育和植物病虫害的生物防治等方面都具有十分重要的意义。本文总结了根际微生物群落构建的研究现状,介绍了根际微生物的经典和最新的研究方法,包括根箱法、同位素技术以及高通量测序、菌群定量分析、高通量分离培养等方法在根际微生物研究中的应用,讨论了植物根系分泌物(碳水化物、氨基酸、黄酮类、酚类、激素及其信号物质)和土壤物理化学性质对根际微生物群落的影响,概述了根际微生物-植物的互作机制,以及根际微生物群落对植物的促生作用、提高植物抗逆性和抑制作用,并对根际微生物群落研究中存在的问题和未来发展方向进行了展望。     

基于菌植互作的植物根际细菌钝化镉作用和机制研究进展

土壤重金属镉(Cd)污染严重危害农产品安全生产,植物根际细菌在钝化土壤Cd和帮助作物抵御Cd胁迫方面发挥重要作用。本文首先概括在修复Cd污染土壤中得到广泛应用的植物根际细菌种类,并从根际细菌直接吸附Cd、调整土壤理化特性、调控土壤微生物群落和其他作用4方面阐述了植物根际细菌对Cd的钝化作用,其次从菌植互作角度阐述植物根系分泌物与根际细菌群落相互影响对土壤Cd的钝化作用。最后展望重金属胁迫下植物根际钝化Cd核心菌群的构建,以在新兴学科与技术的快速发展中探明植物根系-微生物互作体系的分子机制,深入开展植物根际细菌钝化修复重金属污染土壤的理论研究和实践。     

重金属不同积累型植物品种的根际生态效应分析

植物对重金属的吸收积累与其根际环境密切相关, 因此对于根际生态效应的研究有助于理解不同品种积累重金属差异的机理。从根系形态、根际土壤化学特性、根系分泌物及微生物特性等方面对根际生态效应和植物积累重金属的关系进行了综述, 旨在从根际方面诠释植物积累重金属差异的机理, 并为重金属积累典型品种的选育提供理论基础。     

植物根系对根际微环境扰动机制研究进展

根际微环境是构建植物与土壤交流沟通的桥梁,也是植物遭受胁迫时优先作出响应的区域。植物根系作为根际的主要调控者,根构型和根系分泌物种类、数量的改变均可对根际微生物和土壤动物种群分布及其结构造成影响。然而,土壤动物的扰动、微生物的分解作用也可改善根际土壤特性,提高植物抗逆性及养分利用效率,从而促进植物根系生长。可见,植物根系-根际动物-根际微生物之间存在复杂的互作关系。本文从根际内、外微环境出发,分析了根际外植物根系对微环境的物理和化学扰动、根际内植物根系与微生物的互作扰动、根际内植物根系和土壤动物的物理扰动、以植物根系分泌物为介质的化学扰动等方面研究进展,在此基础上,论述了根际微环境主要影响因子之间的互作机制,并对该领域的研究方向进行了展望。     

入侵植物对根际土壤微生物群落影响的研究进展

入侵植物根际土壤微生物是地下生态系统的重要组成部分。外来植物入侵到新的栖息地后能够促进其根际土壤微生物群落结构的演替、改变土壤理化性质, 强化微生物群落功能的发挥, 进而创造更适合外来植物生长的土壤微环境, 促进外来种的入侵进程。从外来入侵植物根际土壤微生物的研究方法、外来入侵植物对根际土壤微生物群落影响以及从地下生态学对外来植物入侵的影响等方面进行了综述。土壤微生物研究方法主要包括微生物计数法、微生物生理生化指标方法及分子技术 3 类; 入侵植物对根际土壤微生物的影响主要体现在对其生物量、多样性以及功能微生物菌群等方面。在今后的研究中, 应当注重对同一区域外来入侵植物和近缘本土种、及其伴生种的根际土壤微生物进行比较研究; 加强入侵植物根际微生物功能机理、环境因子与微生物间关联性的研究; 同时在研究方法上应注重传统方法与生物标记法及其与分子技术的结合。     

植物根压研究进展

根压是植物根部产生的一种静水压力,广泛存在于多种植物中。在蒸腾作用很弱的情况下,根压不但可驱动水分从根部流向冠层叶片,缓解因白天强烈蒸腾而导致的水分亏缺,而且在木质部导管栓塞修复方面具有重要作用。虽然国内外学者对根压的产生已有一些解释,普遍接受的观点有渗透理论、代谢理论和水分向上共同运输假说等,但根压产生的机制至今仍是科学家争议的焦点之一。根压的测定方法虽有直接和间接测定、损伤和无损伤测定之分,但较为先进的根压测定技术仍需进一步改善和提升。受水通道蛋白、遗传因素、生境等因素的影响,根压的大小存在差异,即使是较低的根压也会影响农作物生长。在促进转运蛋白质、酶、氨基酸、激素及钙元素等在农作物木质部和韧皮部之间流通方面,适当大小的根压发挥重要作用,且有助于提高农作物产量。因此,加深对植物根压的认识和理解具有重要的生物学意义。该文从根压的定义和产生机制、具有根压的植物类群、根压的测定方法和大小、影响根压的主要因素及根压在植物科学研究领域的意义和影响等多个方面分别进行了归纳总结,并结合当前研究热点和研究成果,针对植物根压研究过程中遇到的问题和后续研究趋势及方向进行了展望。     

根癌农杆菌转化单子叶植物研究概况

单子叶植物过去被人们公认公以为难以用根癌农杆菌转化,但最近有了新的进展。本文对用根癌农杆菌在转比单子叶植物方面的研究历史、现状、所取得的成功以及酚类化合物对根癌农杆菌介导的转化的促进作用做了较为详细的综述。     

植物根系分泌物主要生态功能研究进展

根系分泌物在植物根系-土壤-微生物互作过程及其生态反馈机制中发挥重要作用。在植物根际复杂网络互作过程中, 根系分泌物被认为是“根际对话”的媒介, 其在调控植物适应微生境、缓解根际养分竞争及构建根际微生物群落结构方面意义重大。该文结合国内外该领域主要研究成果, 综述了根系分泌物对植物生长、土壤微生物特性及土壤养分循环的影响, 并展望了未来根系分泌物的研究方向。     

Water Movement Through Plant Roots

Mathematical analysis of the hydraulics of water movement throughplant roots, in terms of radial and axial resistances, has ledto equations which provide new insights into the effects ofthe component resistan ces on water uptake by and movement throughindividual roots and root systems. The ratio of axial to radialresistance determines the optimum length of a root and its totalresistance to water movement. The equations permit direct calculationsof the plant water potentials necessary, at the base of theplant, to sustain given flow rates through root systems withgiven characteristics. Lateral spacing and the resistance ofindividual laterals are the dominant factors determining totalflux per unit area into a root. When soil water potential increases with depth (surface layersdrier) root resistance tends to decrease with increasing flowrate; the reverse occurs when the surface is wetter than thelower layers. Calculated patterns of water movement into andthrough roots, in relation to soil water potential and flowrate through the root, indicate efflux from root to soil undercertain conditions. This is considered to reflect reality, althoughthe fluxes are probably transient or intermittent. The equations presented should be combined with equations describingwater movement through soil to define the behaviour of the wholeroot-soil system adequately.     

植物根构型的定量分析

植物根系具有锚定植株、吸收和运输土壤中的水分及养分、合成和贮藏营养物质等重要功能。根构型是根系在土壤中的空间造型和分布。对植物根构型进行定量分析, 有助于人们了解根系结构和根系功能在生态系统中的重要作用。本文对植物根构型的概念及其定量分析研究进展进行了概述, 并介绍了植物根构型的主要研究方法和定量分析技术。     

植物根构型的定量分析

植物根系具有锚定植株、吸收和运输土壤中的水分及养分、合成和贮藏营养物质等重要功能。根构型是根系在土壤中的空间造型和分布。对植物根构型进行定量分析,有助于人们了解根系结构和根系功能在生态系统中的重要作用。本文对植物根构型的概念及其定量分析研究进展进行了概述,并介绍了植物根构型的主要研究方法和定量分析技术。     

A Soil-free Plant Growth System to Facilitate Analysis of Plant Pathogen Interactions in Roots

Analysis of the interaction of pathogens with plant roots is often complicated by the growth of plants in a soil substrate. A soil-free plant growth system (SPS) was developed that removes the need for a substrate while supporting the growth of seedlings in a nutrient rich, oxygenated environment. The model legume Lupinus angustifolius was used to compare the growth of seedlings within soil and the SPS. Seedlings grown under both conditions were similar in morphology, anatomy and health (measured by leaf chlorophyll abundance) and importantly there was little difference in root growth and development although straighter and fuller root systems were achieved in the SPS. The ease of access to the root system proved efficient for the analysis of root and pathogen interactions with no interference from soil or adhering particulate matter. Following inoculation of L. angustifolius roots with Phytophthora cinnamomi the host/pathogen interaction was easily observed and tissues sampled undamaged.     

Plant nutrition and growth: Basic principles

Soil compaction may restrict shoot growth of sugar beet plants. Roots, however, are the plant organs directly exposed to soil compaction and should therefore be primarily affected. The aim of this study was to determine the influence of mechanical resistance and aeration of compacted soil on root and shoot growth and on phosphorus supply of sugar beet. For this purpose, a silt loam soil was adjusted to bulk densities of 1.30, 1.50 and 1.65 g cm^–3 and water tensions of 300 and 60 hPa. Sugar beet was grown in a growth chamber under constant climatic conditions for 4 weeks. Both, decrease of water tension and increase of bulk density impeded root and shoot growth. In contrast, the P supply of the plants was differently affected. At the same air-filled pore volume, the P concentration of the shoots was reduced by a decrease of soil water tension, but not by an increase of bulk density. Both factors also reduced root length and root hair formation, however, in compacted soil the plants partly substituted for the reduction of root size by increasing the P uptake efficiency per unit of root. Shoot growth decreased when root growth was restricted. Both characteristics were closely related irrespective of the cause of root growth limitation by either compaction or water saturation. It is therefore concluded that shoot growth in both the compacted and the wet soil was regulated by root growth. The main factor impeding root growth in compacted soil was penetration resistance, not soil aeration.FAX no corresponding author: +49551 5056299     

Constitutive Autophagy in Plant Root Cells

In previous studies, using a membrane-permeable protease inhibitor, E-64d, we showed that autophagy occurs constitutively in the root cells of barley and Arabidopsis. In the present study, a fusion protein composed of the autophagy-related protein AtAtg8 and green fluorescent protein (GFP) was expressed in Arabidopsis to visualize autophagosomes. We first confirmed the presence of autophagosomes with GFP fluorescence in the root cells of seedlings grown on a nutrient-sufficient medium. The number of autophagosomes changed as the root cells grew and differentiated. In cells near the apical meristem, autophagosomes were scarcely found. However, a small but significant number of autophagosomes existed in the elongation zone. More autophagosomes were found in the differentiation zone where cell growth ceases but the cells start to form root hair. In addition, we confirmed that autophagy is activated under starvation conditions in Arabidopsis root cells. When the root tips were cultured in a sucrose-free medium, the number of autophagosomes increased in the elongation and differentiation zones, and a significant number of autophagosomes appeared in cells near the apical meristem. The results suggest that autophagy in plant root cells is involved not only in nutrient recycling under nutrient-limiting conditions but also in cell growth and root hair formation.

Addendum to:

AtATG Genes, Homologs of Yeast Autophagy Genes, are Involved in Constitutive Autophagy in Arabidopsis Root Tip Cells

Y. Inoue, T. Suzuki, M. Hattori, K. Yoshimoto, Y. Ohsumi and Y. Moriyasu

Plant Cell Physiol 2006; 47:1641-52     

Plant root growth, architecture and function

Without roots there would be no rhizosphere and no rhizodeposition to fuel microbial activity. Although micro-organisms may view roots merely as a source of carbon supply this belies the fascinating complexity and diversity of root systems that occurs despite their common function. Here, we examine the physiological and genetic determinants of root growth and the complex, yet varied and flexible, root architecture that results. The main functions of root systems are also explored including how roots cope with nutrient acquisition from the heterogeneous soil environment and their ability to form mutualistic associations with key soil micro-organisms (such as nitrogen fixing bacteria and mycorrhizal fungi) to aid them in their quest for nutrients. Finally, some key biotic and abiotic constraints on root development and function in the soil environment are examined and some of the adaptations roots have evolved to counter such stresses discussed.     

Allometric Effects on Plant Interference

The way interference develops in even-aged monocultures is usuallyjudged from the progression of weight-density curves that thestands exhibit. For whole plant weight-density curves this developmentof interference is unaffected by root:shoot allometric changesin themselves. However, for weight (of a plant part) - densitycurves, e.g. shoot weight - density curves, differing root:shootallometries in populations can change the way in which interferencedevelops. For example, in shoot weight-density curves, increasingthe proportion of total weight which is root increases the areaoccupied by an isolated plant and so decreases the density atwhich interference becomes appreciable. Increasing the proportionof total weight which is shoot, as density increases, increasesthe area occupied by an isolated plant but also decreases therate at which density constrains shoot weight. Interference, allometry, root:shoot ratio, competition     

组织透明技术在植物解剖学和植物发育生物学实验教学中的应用

整体组织透明和组织切片技术是研究植物组织和器官的结构及其发育过程的常用实验手段。该文针对本科生植物学课程的侧根、胚珠(特别是胚囊)以及胚胎发育内容设计了相应的实验教学课程。该实验以拟南芥幼苗、不同发育时期的花蕾和种子为材料,经固定、脱色和组织透明,利用正置显微镜观察侧根、胚珠以及胚胎的发育过程。根组织经透明后,在显微镜下可以清晰地观察到从侧根原基的建成到侧根发生的八个发育阶段。各个发育时期的胚珠经组织透明后,在显微镜下可以清晰地观察到大孢子母细胞、功能性大孢子(FG1期)以及FG2~FG7期的胚囊。各个发育时期的种子经透明后,在显微镜下可以清晰地观察到胚胎发育的1细胞期、8细胞期、球形期、心形期、鱼雷期、拐杖期和成熟期。这些实验结果可以使学生对拟南芥等双子叶植物的侧根、胚珠以及胚胎发育过程有较为系统的了解。该实验方法在其他较小的双子叶植物中也适用。     

植物生根的分子机理研究进展

随着无性系育种在农林业上的广泛应用,其生根难的问题显得尤为突出。通过查阅相关文献,本文探讨了影响植物根发育的分子机理。从植物激素,主要从生长素调控植物根发育的分子机理;细胞周期相关基因影响植物根发育和与细胞壁形成相关的基因影响植物根发育等方面叙述了目前关于植物根发育的研究进展。并提出了解决研究生根分子机理材料难选择问题的方法。