A Simple Hydroponic Culture Method for the Development of a Highly Viable Root System in Arabidopsis thaliana

In the studies of nutritional absorption and metal toxicity in the root, it is important to grow plants without technical damage. We established a simple hydroponic culture system for Arabidopsis thaliana to obtain a healthy plant having a well-developed root system with many lateral roots. The phytotoxic effects of Cr, Cu, and Al ions were examined by FDA-PI staining using this culture system. The pattern of root inhibition varied with the ion, suggesting the usefulness of this culture system.     

玉米根系水流导度差异及其与解剖结构的关系

在人工气候室水培条件下,从单根水平研究了不同水分条件下玉米根系水流导度的基因型差异及解剖结构之间的关系.结果表明,抗旱性的杂交种户单四号具有水流导度上的杂种优势现象,不抗旱的父本803根系水流导度最低,3个品种根系水流导度大小为F₁代户单四号＞母本天四＞父本803;水分胁迫普遍降低了根系直径、导管直径和皮层厚度.同时,玉米品种根系的解剖结构和根系水流导度有关,正常水分条件下,根系导管直径与3个玉米品种的根系水流导度呈正相关,胁迫条件下则呈负相关.无论是在胁迫还是正常水分条件下,根系皮层厚度占根系直径的比例与根系水流导度都呈负相关,说明根系皮层是根系吸收水分的主要阻力部位.     

Adaptive Changes and Genotypic Variation for Root Architecture of Common Bean in Response to Phosphorus Deficiency

Root architectural responses to phosphorus (p) availability may be an important trait for P acquisition efficiency. In the present study, The authors examined the effects of P availability on root architectural responses of different common bean genotypes. Five common bean (Phaseolus vulgaris L.) genotypes representing different origins and ecotypic races were compared both in a specially designed paper pouch system and a stratified P buffer sand culture system with computer image analysis. The results showed that root architecture was regulated by P availability. P deficiency led to form a shallower root system, as indicated by increased relative distribution of basal root length in the upper layers and decreased the growth angle of basal roots. There was significant genetic variation in root architecture in response to P deficiency both in the paper pouch system and the stratified sand culture system. Under low P conditions some genotypes were more gravitropically sensitive to low P availability, resulting in producing a shallower root system and enhanced root exploration into the surface soil, where soil available P is more concentrated. G19833 and DOR364, which were most contrasting in P efficiency, were also very different in root architectural response to P availability. The results from this study suggest that P availability regulates root architecture and P deficiency leads to shallower root architecture in beans. The genetic potential of root architecture provides the possibility of selecting this trait for improving P acquisition efficiency in common bean.     

Computational fluid dynamics modeling of mass transfer behavior in a bioreactor for hairy root culture. I. Model development and experimental validation

A two-dimensional axisymmetric computational fluid dynamics (CFD) model based on a porous media model and a discrete population balance model was established to investigate the hydrodynamics and mass transfer behavior in an airlift bioreactor for hairy root culture.During the hairy root culture of Echinacea purpurea, liquid and gas velocity, gas holdup, mass transfer rate, as well as oxygen concentration distribution in the airlift bioreactor were simulated by this CFD model. Simulative results indicated that liquid flow and turbulence played a dominant role in oxygen mass transfer in the growth domain of the hairy root culture. The dissolved oxygen concentration in the hairy root clump increased from the bottom to the top of the bioreactor cultured with the hairy roots, which was verified by the experimental detection of dissolved oxygen concentration in the hairy root clump. This methodology provided insight understanding on the complex system of hairy root culture and will help to eventually guide the bioreactor design and process intensification of large-scale hairy root culture.     

分室培养装置在丛枝菌根真菌研究中的应用及其发展

重点围绕玻璃珠分室培养系统、H形分室培养系统、根排斥室培养系统、供体自养植物的双分室体外培养系统、丛枝菌根(AM)真菌与普通植物根器官的双重培养系统、AM真菌与Ri T-DNA转型根的双重单胞无菌培养系统、AM真菌与Ri T-DNA转型根双重培养的改良分室单胞培养系统等7个不同的分室培养装置, 对AM真菌的培养类型及其应用进行了系统的评述。其中, 采用玻璃珠分室培养装置易于将AM真菌与培养基质分开, 能获得大量纯净的AM真菌繁殖体, 用于研究AM真菌对矿质元素和微量元素的吸收, 具有不可替代的作用。H形分室培养系统和根排斥室(RECs)培养系统均能够获得连续的、可切断的共生菌根网络(CMNs), 可用于研究植物-植物、植物-昆虫之间化感作用产生的信息交流。供体自养植物的双分室培养系统有益于研究AM真菌对宿主植物在单作和混作条件下生长效应的影响。AM真菌与植物根器官的双重培养系统为研究AM真菌的侵染过程及生理、生化特性提供了极大的方便, 同时为纯培养研究提供了重要的理论依据。AM真菌与Ri T-DNA转型根的双重单胞无菌培养体系可以获得AM真菌纯净菌体, 是研究AM真菌遗传、生理、生化等特性的理想方法。以AM真菌与Ri T-DNA转型根的双重单胞无菌培养系统为基础, 可以在菌丝生长室置换培养基、在根室中补充适量碳源, 并多次收获AM真菌繁殖体。转型根改良双重培养系统是提高AM真菌孢子接种剂产量的有效方法。综上所述, AM真菌的分室培养系统已经取得显著进展, 为开展个体、种群、群落等不同层次的菌根生态学研究提供了依据。     

Long-term culturing of plants with aseptic roots Determination of rape root exudates

Abstract A plant culture system allowing growth of aseptic roots has been designed. One version of the system comprises vessels developed for plant root-microorganism interaction studies in series. A second version has been built for measurements of different physiological parameters of the shoot and root system during growth periods of at least 2 months. The system was tested by determining soluble organic carbon glucose and sucrose in the root exudates of rape plants (Brassica napus L.) grown for 3 weeks in the culture system. The plants were cultivated with a sterile or a non-sterile root system, or with a root system infected with Verticillium dahliae Kleb.     

玉米离体根尖的多层滤纸床液体静止培养方法

设计建立了适于玉米根尖离体培养的多层滤纸床液体静止培养方法,培养的适宜体系为：1／4MS大量元素改良＋1／2MS微量元素＋IBA0.1-0.3mg/L,黑暗培养。该方法避免了传统液体培养通气状况不良的问题,玉米根的生长速度可达到1－2cm/d,分支和生长正常。该方法在控制条件下快速繁殖根系,成本低廉,简便易行,是根系发育和生理研究的理想实验体系。     

镉、铅及其相互作用对小白菜根系生理生态效应的研究

采用溶液培养方法,以镉,铅作为胁迫因子,研究了不同镉,铅浓度对小白菜根系生理生态的影响。实验结果表明;培养液中镉超过０．１ｍｇ／Ｌ,侧根数目减少,根的分枝程度降低,根系生物量和体积下降,根系生长发育受阻,根系不发达,根系对锰,锌的吸收受到抑制,根系活动降低,对硝酸盐吸收能力下降,蛋白质分解加快,游离氨基酸积累,氮代谢紊乱,失调。     

Induced biosynthesis of resveratrol and the prenylated stilbenoids arachidin-1 and arachidin-3 in hairy root cultures of peanut: Effects of culture medium and growth stage

Previously, we have shown that hairy root cultures of peanut provide a controlled, sustainable and scalable production system that can be induced to produce stilbenoids. However to leverage peanut hairy roots to study the biosynthesis of this polyphenolic biosynthetic pathway, growing conditions and elicitation kinetics of these tissue cultures must be defined and understood. To this end, a new peanut cv. Hull hairy root (line 3) that produces resveratrol and its prenylated analogues arachidin-1 and arachidin-3 upon sodium acetate-mediated elicitation was established. Two culture media were compared for impact on root growth and stilbenoid biosynthesis/secretion. The levels of ammonium, nitrate, phosphate and residual sugars were monitored along growth and elicitation period. A modified MS (MSV) medium resulted in higher root biomass when compared to B5 medium. The stilbenoid profile after elicitation varied depending on the age of the culture (6, 9, 12, and 15-day old). After elicitation at day 9 (exponential growth in MSV medium), over 90% of the total resveratrol, arachidin-1 and arachidin-3 accumulated in the medium. Our studies demonstrate the benefits of the hairy root culture system to study the biosynthesis of stilbenoids including valuable prenylated polyphenolic compounds.     

Inhibitory role of root hairs on transport within root culture bioreactors

An experimental system was developed to produce root cultures of Hyoscyamus muticus with and without the profuse root hairs. Growth in the presence of 7.6 microM pyrene butyric acid (PBA) and 2.2 mM phosphate virtually eliminated root hairs, whereas growth rate, general morphology and nutrient yields remained unchanged in well-mixed flask culture. These root cultures were used to demonstrate decreased flow resistance in a tubular reactor as a result of root hair removal. To assess the impact on bioreactor performance, hairy and hairless root cultures were grown in a highly characterized 15-L bubble column bioreactor. In the absence of root hairs, the mixing was greatly enhanced; mixing times became shorter for the hairless culture at roughly 100 g (fresh weight)/L. By the end of the 3-week culture period, the mixing time of the hairy culture was 29 times longer than that of the hairless culture. The growth rate of the hairless culture in the bioreactor was as much as 2.4 times greater than growth of the hairy culture under the same conditions. The improved reactor performance was reflected in greater biomass accumulation and respiratory activity. These results show that the root hairs-which facilitate nutrient uptake in a static soil environment-are detrimental to growth in a liquid environment as an effect of their stagnating fluid flow and limiting oxygen availability.     

Continuous, automated acetylene reduction assays using intact plants

An automated method was developed for continuous, in situ determination of acetylene reduction (N₂ fixation) by intact soybean plants (Glycine max [L.]). The culture vessel containing the roots of intact plants grown in sand culture is sealed at the surface and an air-acetylene mixture continuously injected into the root chamber. The effluent gas is automatically sampled and injected into a gas chromatograph. Continuous acetylene assay at intervals as short as 3.5 min may be made over a period of several days, without attention, except for plant watering. Adverse effects of prolonged exposure of the root system to acetylene were mitigated by pulse injection of acetylene for 20 min followed by 40 min of acetylene-free air. Bare root systems can be suspended in a reaction chamber and sprayed with water or nutrient solution; this permits periodic removal of the root system for sampling nodules.     

硝态氮(NO-3)对水稻侧根生长及其氮吸收的影响

侧根是植物吸收利用土壤养分的重要器官,其生长发育受内部遗传因子和外部环境矿质养分的影响.通过琼脂分层培养发现:局部供应NO-3可以诱导水稻( Oryza sativa L.)主根或不定根上侧根的生长.为研究旱种条件下NO-3对水稻侧根发育及其N吸收的影响,设置了3个蛭石培养实验:分根处理、全株缺N、全株供N处理.分根处理(一半根系供应3 mmol/L KNO3,另一半根系供应3 mmol/L KCl)结果表明:局部供应NO-3 能够促进水稻侧根生长.而在全株处理下,N饥饿诱导了侧根的伸长.水稻根系对NO-3的这两种反应都存在着显著的基因型差异.同时对地上部N浓度、可溶性总糖含量及N含量分析表明,这些生理指标在分根处理与全株加N处理中的差异均不显著,表明分根处理也能基本满足植株正常生长对N的需求.在分根处理中,水稻的N含量与分根处理中供N一侧的平均侧根长度存在显著正相关,这表明在养分不均一的介质中,侧根长度对水稻N素吸收具有十分重要的作用.而在N素充足的条件下,两者之间的相关性并不显著,这暗示在养分充足的环境下,侧根长度可能并不是决定根系吸收N素的主要因素.     

硝态氮（NO3^—）对水稻侧根生长及其氮吸收的影响

侧根是植物吸收利用土壤养分的重要器官 ,其生长发育受内部遗传因子和外部环境矿质养分的影响。通过琼脂分层培养发现 :局部供应NO-3 可以诱导水稻 (OryzasativaL .)主根或不定根上侧根的生长。为研究旱种条件下NO-3 对水稻侧根发育及其N吸收的影响 ,设置了 3个蛭石培养实验 :分根处理、全株缺N、全株供N处理。分根处理 (一半根系供应 3mmol/LKNO3,另一半根系供应 3mmol/LKCl)结果表明 :局部供应NO-3 能够促进水稻侧根生长。而在全株处理下 ,N饥饿诱导了侧根的伸长。水稻根系对NO-3 的这两种反应都存在着显著的基因型差异。同时对地上部N浓度、可溶性总糖含量及N含量分析表明 ,这些生理指标在分根处理与全株加N处理中的差异均不显著 ,表明分根处理也能基本满足植株正常生长对N的需求。在分根处理中 ,水稻的N含量与分根处理中供N一侧的平均侧根长度存在显著正相关 ,这表明在养分不均一的介质中 ,侧根长度对水稻N素吸收具有十分重要的作用。而在N素充足的条件下 ,两者之间的相关性并不显著 ,这暗示在养分充足的环境下 ,侧根长度可能并不是决定根系吸收N素的主要因素     

不同供水条件下水稻幼苗根系形成的遗传分析

利用分子标记图谱对溶液培养与旱作培养（纸培养）下的水稻（Oryza sativa L.)幼苗的种子根与最长不定根长,不定根数,总根干重,根冠比等性状进行了基因定位与遗传分析。4种参数共检测到6个数量性状位点（quantitative trait loci,QTLs)与22对上位性互作位点,其中溶液培养中的最长不定根长,总根干重和旱作培养中的总根干重检测到的QTLs位点对总变异的贡献率分别为20％,23％和13％左右;旱作培养中的最长不定根长,不定根数,根冠比和溶液培养中的根冠比仅检测到上位性位点,对表型变异的贡献率在12％－61％之间,溶液培养与旱作条件下没有一个或一对检测到的QTL或互作位点完全相同,提示溶液培养和旱作条件下影响幼苗根系生长的遗传机制差异,上位性作用对旱作培养条件下的根生长具重要影响。     

Increase of Scopolamine Production by High Density Culture of Duboisia myoporoides Roots

A circulation culture system was established for the high density root culture of Duboisia roots. It consists of a vessel for root culture, an aeration tube, a medium reservoir, and a peristaltic pump. Medium saturated with pure oxygen was circulated continuously through the culture vessel and the medium reservoir, and was pumped back into the aeration tube by the pump. Duboisia roots could be cultured at densities of up to 120g dry weight (DW) dm^?3 with no decrease in scopolamine content, this density being about 20 times the amount that can be used in ordinary flask culture. The final scopolamine yield at the end of 3 weeks was 1350mgdm^?3.     

垄作与覆膜对川中丘陵春玉米根系分布及产量的影响

通过设置田间试验,研究种植方式(垄作垄播、平作、垄作沟播)与覆膜措施对川中丘陵春玉米根系分布和玉米产量的影响.结果表明: 垄作与覆膜对玉米根系形态影响显著,覆膜显著提高了玉米根长、根表面积和根体积,拔节期覆膜较不覆膜处理分别提高了42.3%、50.0%和57.4%.覆膜提高了各土层和各水平各层次根质量,扩大了根系在土壤垂直和水平方向上的分布,提高了拔节期20～40 cm土层和水平方向上宽行0～20 cm根系比例.种植方式对根系生长和分布的影响因覆膜而异,覆膜下垄作垄播显著提高了各土层根质量和20～40 cm土层根量分配比例,同时提高了水平方向上各层次根量和宽行根系分配比例,总根质量表现为:垄作垄播>平作>垄作沟播;不覆膜下垄作沟播显著提高了窄行0～40 cm根量,吐丝期总根质量表现为:垄作沟播>垄作垄播>平作.从玉米穗部性状和产量看,覆膜降低了玉米秃尖长,提高了穗长、穗粒数、千粒重和产量,覆膜下产量表现为:垄作垄播＞平作＞垄作沟播;不覆膜下则表现为:垄作沟播＞平作＞垄作垄播.覆膜下垄作垄播促进了根系特别是深层根质量的增加,同时增加了深层根系和水平20～40 cm根系比例,这是其增产的重要原因;而不覆膜下垄作沟播有利于根系生长,从而提高产量.     

一种简单有效的非损伤观测根瘤和根系形态的方法

实时观测根瘤及根系形态对于豆科植物研究具有重要意义, 但目前还缺乏一个便于观测根系、高效结瘤、适宜生长且经济实用的豆科植物培养体系。以蒺藜苜蓿(Medicago truncatula)为植物材料, 建立了一种可实时观测根瘤及根系形态的纸袋水培法, 并与其它常用方法进行对比。结果表明, 依赖于石英砂等固体介质栽培蒺藜苜蓿对根瘤和根系形态的实时观测造成障碍, 而水培和喷雾培养等方法的根瘤菌接种效率不高, 且不便观测侧根发育情况。采用纸袋水培法探讨了褪黑素对蒺藜苜蓿根系发育的影响, 发现褪黑素具有降低根瘤形成效率、抑制侧根伸长、增加侧根数目以及增大侧根与主根之间夹角等作用。因此, 纸袋水培法能够高效接种根瘤菌且为实时无损伤观测根瘤及根系形态提供了可能, 是一种适用于豆科植物简单有效的培养方法。     

QTLs and epistasis for seminal root length under a different water supply in rice (Oryza sativa L.)

To identify the genetic background of seminal root length under different water-supply conditions, a recombinant inbred (RI) population consisting of 150 lines, derived from a cross between an indica lowland rice, IR1552, and a tropical japonica upland rice, Azucena, was used in both solution culture (lowland condition) and paper culture (upland condition). Quantitative trait loci (QTLs) and epistatic loci for seminal root length were analyzed using 103 restriction fragment length polymorphism (RFLP) markers and 104 amplified fragment length polymorphism (AFLP) markers mapped on 12 chromosomes based on the RI population. One QTL for seminal root length in solution culture (SRLS) and one for seminal root length in paper culture (SRLP) were detected on chromosomes 8 and 1, and about 11% and 10% of total phenotypic variation were explained, respectively. The QTL for SRLP on chromosome 1 was very similar with the QTL for the longest nodal root referred to in a previous report; this QTL may be phenotypically selectable in a breeding program using paper culture. Five pairs of epistatic loci for SRLS were detected, but only one for SRLP, which accounted for about 60% and 20% of the total variation in SRLS and SRLP, respectively. The results indicate that epistasis is a major genetic basis for seminal root length, and there is a different genetic system responsible for seminal root growth under different water supply conditions. Received: 26 May 2000 / Accepted: 19 October 2000     

Root system architecture in Arabidopsis grown in culture is regulated by sucrose uptake in the aerial tissues

This article presents a detailed model for the regulation of lateral root formation in Arabidopsis thaliana seedlings grown in culture. We demonstrate that direct contact between the aerial tissues and sucrose in the growth media is necessary and sufficient to promote emergence of lateral root primordia from the parent root. Mild osmotic stress is perceived by the root, which then sends an abscisic acid-dependent signal that causes a decrease in the permeability of aerial tissues; this reduces uptake of sucrose from the culture media, which leads to a repression of lateral root formation. Osmotic repression of lateral root formation in culture can be overcome by mutations that cause the cuticle of a plant's aerial tissues to become more permeable. Indeed, we report here that the previously described lateral root development2 mutant overcomes osmotic repression of lateral root formation because of a point mutation in Long Chain Acyl-CoA Synthetase2, a gene essential for cutin biosynthesis. Together, our findings (1) impact the interpretation of experiments that use Arabidopsis grown in culture to study root system architecture; (2) identify sucrose as an unexpected regulator of lateral root formation; (3) demonstrate mechanisms by which roots communicate information to aerial tissues and receive information in turn; and (4) provide insights into the regulatory pathways that allow plants to be developmentally plastic while preserving the essential balance between aboveground and belowground organs.