The effect of plant growth regulator treatments on the levels of ethylene emanating from excised turgid and wilted wheat leaves

Abscisic acid (ABA) inhibits the production of ethylene induced by water stress in excised wheat leaves and counteracts the stimulatory effect of 6-benzyladenine (BA) on this process. The stimulatory effect of BA and the inhibitory effect of ABA were equally pronounced whether external or endogenous ethylene levels were determined. When leaves were sprayed or floated on solutions of BA, indole-3-acetic acid (IAA), gibberellic acid (GA₃), or ABA, the relative activities of these growth regulators on stress-induced ethylene at 10^-4 mol l^-1 were BA>IAA >GA₃>controls>ABA. In non-stressed leaves, however, where the levels of ethylene produced were 2–20 times smaller, the relative activities were IAA >BA>GA₃>controls>ABA. The effects of BA and ABA spray treatment on water stress induced ethylene were closely similar whether the solutions were applied 2 or 18 h prior to the initiation of water stress. The relationships between the levels of endogenous growth regulators in the plant and ethylene release induced by water stress are discussed.Abbreviations BA 6-benzyladenine - IAA indole-3-acetic acid - GA₃ gibberellic acid - ABA abscisic acid - GLC gas-liquid chromatography - _leaf leaf water potential     

A role for ethylene in low-oxygen signaling in rice roots

Summary. Inhibitors of action and synthesis of ethylene (Ag⁺, norbornadien, Co²⁺) were able to reduce the level of γ-aminobutyric acid (Gaba) in rice roots during the development of an anaerobic environment. The inhibitory effect was reversed by the addition of the G protein activator 5′-guanylylimidodiphosphate. Gaba accumulation was modulated by the presence of CO₂ (inhibitor of ethylene action and synthesis) and stimulated by 2-chloroethylphosphonic acid (ethefon). These findings are consistent with a role of ethylene during a low-oxygen stress.     

Analysis and regulation of legume inoculants in Canada: The need for an increase in standards

Herbicide residues may affect seedlings during early stages of their development. We studied this possibility by the use of light and electron microscopy after incubation of germinating seeds ofPisum sativum L. andZea mays L. with different concentrations of chlorsulfuron and metsulfuron-methyl. By in vitro experiments, we have shown that both herbicides caused growth reduction of the very young roots, and severe ultrastructural alterations and injuries of the root caps of both species. Chlorsulfuron caused increase of electron-dense material in the vacuoles, cytoplasmic degeneration even in the inner secretory cell layers of the cap, and disruption of the amyloplast envelopes with release of the statolithic starch grains. In the initial cell complex of the root cap, the herbicides caused the formation of large concentric aggregates of the rough ER and wall disformations in the cells adjacent to this complex. Scanning electron microscopic observations revealed a decrease of the slime layer ensheathing the root cap and the subapical root surface.We conclude that even in early stages of seed germination, both herbicides seriously affect the gravity perception centre (consisting of the statocytes), and the secretory tissue of the root caps, thus probably disturbing the processes of gravitropism and the protective slime secretion of the roots.     

Suitability of pollen sources for the development and reproduction of Coleomegilla maculata (Coleoptera: Coccinellidae) under simulated drought conditions

Laboratory experiments compared the nutritive value of various pollen sources for the development of Coleomegilla maculata DeGeer under conditions of continuous water availability and simulated drought. When water was continuously available, larval survival was not different from 100% on diets of frozen eggs of Ephestia kuehniella Zeller, corn pollen, sorghum pollen, or pulverized bee pollen, whereas survival of larvae was significantly reduced on the latter three diets in the simulated drought treatment. Pollen of cultivated sunflower, Helianthus annus L., proved fatal to both larvae and adults; its surface structure caused clumping and accumulation on the insect cuticle that led to death from exhaustion/desiccation in petri dishes. The Ephestia egg diet yielded shorter developmental times and heavier adult weights than any pollen diet in both treatments. The drought treatment increased developmental time on all diets with a significant treatment–diet interaction. Drought reduced the adult weight of females on the sorghum pollen diet, and that of both sexes on the bee pollen diet, again with a significant treatment–diet interaction. Initial water content was highest in corn pollen (36.8%), followed by Ephestia eggs (29.2%), sorghum pollen (25.3%), sunflower pollen (8.7%), and bee pollen (4.6%), but did not appear correlated with C. maculata larval survival on pollen sources under drought conditions. Reproductive adult females that received corn or sorghum pollen as a supplement to Ephestia eggs did not differ in fecundity or fertility from those fed only Ephestia eggs.     

Differential influence of a monotypic and diverse native aquatic plant bed on a macroinvertebrate assemblage; an experimental implication of exotic plant induced habitat

Aquatic plants mediate ecological processes in aquatic habitats, specifically predator–prey (bluegill sunfish (Lepomis macrochirus Rafinesque)-macroinvertebrate) interactions. Macroinvertebrate colonization is directly and indirectly influenced by substrate heterogeneity, interstitial space, and surface complexity. Exotic invasive plant species, such as Hydrilla verticillata L.F. Royle, may alter the available structure in aquatic habitat by creating a shift to a homogeneous habitat, thus affecting the macroinvertebrate community. Since macroinvertebrates provide a food base for young phytophilic fishes, changes in their density and abundance may alter food webs. We investigated the hypothesis that macroinvertebrate community structure is influenced by differences in habitat heterogeneity by measuring difference between a heterogeneous native aquatic plant bed, homogenous hydrilla plant bed, and habitat with no plants. Studies were conducted in the field (pond) and the experimental treatments were: (1) no plants, (2) monotypic bed of hydrilla, and (3) diverse native plants. Aquatic plants, regardless of species, supported greater macroinvertebrate abundance, richness, and biomass. Macroinvertebrate abundance, richness, and biomass in a hydrilla-dominated habitat did not differ significantly from a diverse plant habitat, except for richness in October. Indicator taxa did differ significantly between respective treatments, suggesting a change in species composition. However, no significant effect of fish predation on macroinvertebrate populations and/or community structure was documented. The data suggest that a shift from a natural mosaic of vegetated habitat to a highly complex monotypic habitat (e.g., exotic hydrilla) may reduce spatial heterogeneity important to structuring a macroinvertebrate assemblage. Handling editor: S. M. Thomaz     

基于基因组的一株土壤固氮菌分离菌株鉴定及其促生作用

[目的] 为获得高效固氮菌株,充分研究利用土壤固氮菌资源。[方法] 选取固氮能力较高的紫色土发育水稻土,采用富集纯化法分离固氮微生物菌株。通过16S rRNA基因系统发育分析和全基因组相关指数比较对新分离菌株进行物种鉴定。采用乙炔还原法和¹⁵N₂示踪法定量测定新分离菌株的固氮能力,通过培养特性和接种效果初步研究固氮菌株的促生作用。[结果] 从紫色土发育水稻土中分离得到1株可在无氮培养基上快速生长的菌株P208。基于16S rRNA基因和基因组92个核心基因的系统发育分析结果表明,新分离菌株P208与Azotobacter chroococcum IAM 12666^T（=ATCC 9043^T）系统发育距离最近（16S rRNA基因相似度为99.79%）。菌株P208与A.chroococcum ATCC 9043^T的基因组平均核苷酸一致性（ANI）、平均氨基酸一致性（AAI）和数字DNA-DNA杂交值（dDDH）高于物种分类阈值（ANI>95%-96%,AAI>95%-96%,dDDH>70%）,最大唯一匹配指数（MUMi）低于物种分类阈值（<0.33）,得出新分离菌株P208为褐球固氮菌（A.chroococcum）。A.chroococcum P208固氮活性为模式菌株A.chroococcum ATCC 9043^T的2.61倍。除固氮能力外,A.chroococcum P208具有IAA生成、溶磷活性和铁载体生成等促进植物生长潜力的培养特性,室内培养条件下接种A.chroococcum P208能够促进水稻、小麦幼苗根系的生长。[结论] 从固氮能力较强的水稻土中分离纯化得到1株具有较强固氮、促生潜力的固氮菌,具有潜在的开发应用价值,可为研究利用生物固氮提供微生物资源。     

Domain-specific mechanosensory transmission of osmotic and enzymatic cell wall disturbances to the actin cytoskeleton

Summary. Plant protoplasts are embedded within surrounding cell walls and the cell wall–plasma membrane–cytoskeleton (WMC) structural continuum seems to be crucial for the proper functioning of plant cells. We have utilised the protoplast preparation methodology to study the organisation and the putative components of the WMC continuum. Application of an osmotic agent evoked plasmolysis of the Zea mays root apex cells which appeared to be cell type- and growth stage-specific. Simultaneous use of wall polysaccharide-digesting enzymes selectively severed linkages between the components of the WMC continuum which changed the plasmolytic patterns in various cell types. This was followed by a reorganisation of filamentous actin aimed to reinforce protoplast boundaries and maintain the functioning of intercellular contact sites, especially at the cross walls. Particularly strong effects were evoked by pectin-degrading enzymes. Such treatments demonstrated directly the differentiated composition of various wall domains surrounding individual cells with the pectin-enriched cross walls (synapses), and the cellulose-hemicellulose network dominating the side walls. The same wall-degrading enzymes were used for in vitro digestion of isolated Lupinus albus cell walls followed by the extraction of wall proteins. Selective release of proteins suggested the importance of wall polysaccharide–protein interactions in the maintenance of the functioning and mechanical stability of root cell walls. Correspondence and reprints: Department of Molecular and Cellular Biology, Adam Mickiewicz University, Międzychodzka 5, 60-371 Poznań, Poland.     

Ability of symbiotic and non-symbiotic rhizospheric microflora of maize (Zea mays) to weather micas and to promote plant growth and plant nutrition

Summary Maize was grown under axenic conditions in laboratory devices, in a K⁺-deficient medium, where biotite was the K⁺ source. In different treatments plants were inoculated by symbiotic (Glomus mosseae) and/or non symbiotic microflora. In those treatments inoculated byGlomus mosseae, the percentage of roots infection after 7 weeks plant growth was 65%. Rhizospheric bacterial population was approximately 10⁸/g (dry weight). Endomycorrhizae stimulated growth and K uptake. Non-symbiotic microflora increased also plant growth but promoted much more biotite weathering and K uptake. Endomycorrhizae and more particularly non-symbiotic microflora increased also Ca and Mg absorption by plants. Possible mechanisms involved and implications in plant growth and pedogenesis are discussed.     

Rhizoids and protonemata of characean algae: model cells for research on polarized growth and plant gravity sensing

Gravitropically tip-growing rhizoids and protonemata of characean algae are well-established unicellular plant model systems for research on gravitropism. In recent years, considerable progress has been made in the understanding of the cellular and molecular mechanisms underlying gravity sensing and gravity-oriented growth. While in higher-plant statocytes the role of cytoskeletal elements, especially the actin cytoskeleton, in the mechanisms of gravity sensing is still enigmatic, there is clear evidence that in the characean cells actin is intimately involved in polarized growth, gravity sensing, and the gravitropic response mechanisms. The multiple functions of actin are orchestrated by a variety of actin-binding proteins which control actin polymerisation, regulate the dynamic remodelling of the actin filament architecture, and mediate the transport of vesicles and organelles. Actin and a steep gradient of cytoplasmic free calcium are crucial components of a feedback mechanism that controls polarized growth. Experiments performed in microgravity provided evidence that actomyosin is a key player for gravity sensing: it coordinates the position of statoliths and, upon a change in the cell's orientation, directs sedimenting statoliths to specific areas of the plasma membrane, where contact with membrane-bound gravisensor molecules elicits short gravitropic pathways. In rhizoids, gravitropic signalling leads to a local reduction of cytoplasmic free calcium and results in differential growth of the opposite subapical cell flanks. The negative gravitropic response of protonemata involves actin-dependent relocation of the calcium gradient and displacement of the centre of maximal growth towards the upper flank. On the basis of the results obtained from the gravitropic model cells, a similar fine-tuning function of the actomyosin system is discussed for the early steps of gravity sensing in higher-plant statocytes.     

Acid growth effects in maize roots: Evidence for a link between auxin-economy and proton extrusion in the control of root growth

The role of proton excretion in the growth of apical segments of maize roots has been examined. Growth is stimulated by acidic buffers and inhibited by neutral buffers. Organic buffers such as 2[N-morpholino] ethane sulphonic acid (MES) — 2-amino-2-(hydroxymethyl)propane-1,3 diol (Tris) are more effective than phosphate buffers in inhibiting growth. Fusicoccin(FC)-induced growth is also inhibited by neutral buffers. The antiauxins 4-chlorophenoxyisobutyric acid (PCIB) and 2-(naphthylmethylthio) propionic acid (NMSP) promote growth and H⁺-excretion over short time periods; this growth is also inhibited by neutral buffers. We conclude that growth of maize roots requires proton extrusion and that regulation of root growth by indol-3yl-acetic acid (IAA) may be mediated by control of this proton extrusion.Abbreviations IAA indol-3yl-acetic acid - ABA abscisic acid - FC fusicoccin - PCIB 4-chlorophenoxy-isobutyric acid - MES 2(N-morpholino)ethane sulphonic acid - Tris 2-amino-2-(hydroxymethyl) propane-1,3-diol - NMSP 2-(naphthylmethylthio)propionic acid     

Low-P tolerance by maize (Zea mays L.) genotypes: Significance of root growth,and organic acids and acid phosphatase root exudation

We investigated some mechanisms, which allow maize genotypes to adapt to soils which are low in available P. Dry matter production, root/shoot-ratio, root length and root exudation of organic acids and acid phosphatase were investigated in four maize genotypes grown under P-deficient and P-sufficient conditions in sterile hydroponic culture. A low-P tolerant, an acid-tolerant and a low-P susceptible genotype of maize were compared with a Swiss commercial cultivar. The study found increased root development and increased exudation of acid phosphatase under P-deficient conditions in all maize genotypes, except for the Swiss cultivar. Effects on root formation and acid phosphatase were greater for the low-P tolerant than for the low-P susceptible, and the acid soil tolerant genotypes. Organic acid contents in root tissues were increased under P deficiency and related to increased PEPC activity. However, the increase in contents was associated with an increase in exudation for the low-P tolerant genotype only. The low-P susceptible genotype was characterized by high organic acid content in roots and low organic acid exudation. The organic acids content in the phloem exudates of shoots was related to root exudation under different P supply, to the difference between lines in organic acids root content, but not to the low-P tolerance or susceptibility of maize genotypes.     

Evaluation in field conditions of a three-dimensional architectural model of the maize root system: Comparison of simulated and observed horizontal root maps

Most existing water and nutrient uptake models are based on the assumption that roots are evenly distributed in the soil volume. This assumption is not realistic for field conditions, and significantly alters water or nutrient uptake calculations. Therefore, development of models of root system growth that account for the spatial distribution of roots is necessary.The objective of this work was to test a three dimensional architectural model of the maize root system by comparing simulated horizontal root maps with observed root maps obtained from the field. The model was built using the current knowledge on maize root system morphogenesis and parameters obtained under field conditions. Simulated root maps (0.45 × 0.75 m) of horizontal cross sections at 3 depths and 3 dates were obtained by using the model for a plant population. Actual root maps were obtained in a deep, barrier-free clay-loamy soil by digging pits, preparing selected horizontal planes and recording root contacts on plastic sheets.Results showed that both the number of cross-sections of axile roots, and their spatial distribution characterized with the R-index value of Clark and Evans (1954), were correctly accounted for by the model at all dates and depths. The number of cross-sections of laterals was also correctly predicted. However, laterals were more clustered around axile roots on simulated root maps than on observed root maps. Although slight discrepancies appeared between simulated and observed root maps in this respect, it was concluded that the model correctly accounted for the general colonization pattern of the soil volume by roots under a maize crop.     

A new bio-formulation containing plant growth promoting rhizobacterial mixture for the management of sheath blight and enhanced grain yield in rice

Three plant growth promoting rhizobacterial (PGPR) strains, PF1,FP7 and PB2, were tested alone and in combinations for suppression ofrice sheath blight disease and promotion of plant growth underglasshouse and field conditions. The mixture of PGPR strainssignificantly reduced the sheath blight incidence when applied as eitherbacterial suspension through seed, root, foliar and soil application inglasshouse conditions, or as talc-based formulation under fieldconditions, compared to the respective individual strains. The averagemean of disease reduction was 29.2% for single strains and45.1% for mixtures. In addition to disease suppression, treatmentwith mixture of PGPR strains promoted plant growth in terms of increasedplant height and number of tillers, and ultimately grain yield. Theaverage increases in yield for single strains were 17.7%, and25.9% in case of mixture. Mixture of three PGPR strains reduceddisease and promoted growth to a level equivalent to two strainmixtures. Though seed treatment of either single strain or strainmixtures alone could reduce the disease, subsequent application to root,leaves or soil further reduced the disease and enhanced the plantgrowth. The mixture consisting of PF1 plus FP7 was the most effective inreducing the disease and in promoting plant growth and grainyield.     

A simplified method for determining 1-aminocyclopropane-1-carboxylic acid (ACC) in plant tissues using a mass selective detector

A sensitive and specific method is described for the routine assay of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in 100–200 mg fresh weight samples of green or etiolated tissue. The method involves high performance liquid chromatography (HPLC) and gas chromatography linked to mass spectrometry (GCMS) and uses ¹⁴C-labelled ACC as an internal standard, N-benzoyl n-propyl ACC as an easily prepared derivative for HPLC and GCMS, and N-benzoyl isobutyl ACC as an internal standard for GCMS. The procedure is faster and safer than an existing GCMS method and more specific and reliable than indirect assays widely in use. The method has been used to measure ACC in maize roots, young leaves of cucumber, and aerobic or anaerobic seedlings of rice.     

Soil fertility management as a factor in weed control: the effect of crimson clover residue,synthetic nitrogen fertilizer,and their interaction on emergence and early growth of lambsquarters and sweet corn

Previous experiments have shown that crimson clover (Trifolium incarnatum L.) used as a green manure may supply weed control benefits as well as nitrogen (N) to a subsequent crop of corn (Zea mays L.). In contrast to use of synthetic N fertilizer, use of fresh, incorporated crimson clover residue as an N source has been found to suppress lambsquarters (Chenopodium album L.) aboveground drymatter accumulation but to only temporarily reduce that of sweet corn. One possible cause of the clover's suppressive effect is the initial low availability of N that may occur after residue incorporation in the soil. A factorial treatment combination of +/– crimson clover residue and four rates of N fertilizer was used in two field experiments to further document the clover's influence on early plant growth and development and to test the hypothesis that low initial N availability is responsible for the clover's previously observed suppressive effects. The presence of crimson clover residue was found to reduce total emergence of lambsquarters by 27%, while application of N fertilizer increased lambsquarters emergence by almost 75%. Lambsquarters emergence was also delayed by the residue treatment. Addition of N did not alleviate the clover's suppressive effect on total emergence or emergence rate of lambsquarters. Sweet corn emergence and emergence rate differed by less than 5% in 0 N/+residue and 0 N/–residue treatments. Applications of N to residue plots suppressed rather than enanced sweet corn emergence. Lambsquarters aboveground biomass accumulation was 46% tower in the residue than nonresidue treatments at 23 days after planting (DAP) and remained 26% lower at 53 DAP. Addition of N did not alleviate the suppressive effect of the clover residue on lambsquarters aboveground drymatter accumulation. Sweet corn aboveground biomass accumulation was not affected by the presence of the clover residue. The results of the experiments indicate that the suppressive effect of crimson clover residue on lambsquarters emergence and growth is not attributable to initial low availability of N. However, given the stimulatory effect of N fertilizer on lambsquarters development, use of crimson clover as an N source would appear to provide weed control benefits both as a direct suppressant of weed emergence and growth and as a substitute for fertilizer N.     

Growth at reduced turgor: irreversible and reversible cell-wall extension of maize coleoptiles and its implications for the theory of cell growth

The relationship between steady-state elongation rate (G) and turgor pressure (P; G/P curve) was investigated using isolated segments of maize (Zea mays L.) coleoptiles incubated in osmotic solutions of a water potential range of 0 to -10 bar (polyethylene glycol 6000 as osmoticum). Short-term elongation measurements revealed curvilinear G/P curves with a steep slope at high turgor and a shallow slope at low turgor. Owing to a decrease of osmotic pressure and turgor, there was a tendency for straightening of the G/P curves during long-term elongation. An elongation rate of zero was adjusted by lowering the turgor by 4.5 bar at a constant osmotic pressure of 6.7 bar. Auxin increased — whereas abscisic acid decreased — the slope of the G/P curve but these hormones had no effect on the threshold turgor of growth (Y = 2.2 bar). It is concluded that extensibility of the growing cell walls represented by the yielding coefficient of Lockhart's growth equation is turgor-dependent and therefore decreases to a very low value as the turgor approaches Y. When the turgor was kept at Y, a constant segment length was maintained over at least 6 h. However, separation of reversible (l_rev) and irreversible (l_irr) components of total (in vivo) length (l_tot = l_rev + l_irr) W measuring segment length before and after freezing/thawing revealed that l_irr increased continuously and l_rev decreased continuously at constant l_tot. After a step-down in turgor the segments grew in l_irr although they shrank in l_tot over the whole turgor range of 0irr irreversible length - l_rev reversible length - l_tot total length (= l_irr + l_rev) - _i osmotic pressure of cell sap - _i water potential of tissue - _o water potential of incubation medium - ABA abscisic acid - G growth rate - m yielding coefficient - P turgor pressure - PEG polyethylene glycol 6000 - Y yield threshold Supported by Deutsche Forschungsgemeinschaft (SFB 206). We thank R. Hertel for helpful comments.     

Changes in radiocaesium uptake and distribution in wheat during plant development: a solution culture study

Spring wheat plants were grown in a ¹³⁷Cs labelled nutrient solution, either in the presence or absence of NH₄ as a secondary N source. Between 11 and 64 days after sowing (DAS), plants were harvested on nine occasions. The plants supplied with NH₄ and NO₃ had lower root ¹³⁷Cs Activity Concentrations (AC) than those supplied with NO₃ only. Shoot AC were equal in both nutrition treatments. Shoot and root ¹³⁷Cs AC (dry weight basis) showed the same trends with plant age in both nutrition treatments. Shoot AC almost doubled between 11 and 28 DAS after which they gradually decreased concomitant with a similar decrease in K concentrations. Root AC were always higher than shoot AC and increased to a maximum at 35 DAS after which they fluctuated. Expressed on a tissue water basis, the ¹³⁷Cs AC varied less during plant age than did dry weight based AC. Furthermore, root and shoot AC expressed on a tissue water basis were almost equal. It is shown that the initial increase in ¹³⁷Cs AC in both root and shoot can largely be explained by the initial dilution of absorbed ¹³⁷Cs in the unlabelled seedling tissues. No correlation was found between K and ¹³⁷Cs distribution among ears, leaves, stems and roots in 64 old wheat plants. NH₄ as a secondary N source in a nitrate nutrient solution marginally affected ¹³⁷Cs distribution.Abbreviations AC activity concentrations - DAS days after sowing FAX no corresponding author: +3216321997     

How plant architecture affects light absorption and photosynthesis in tomato: towards an ideotype for plant architecture using a functional-structural plant model

Background and Aims

Manipulation of plant structure can strongly affect light distribution in the canopy and photosynthesis. The aim of this paper is to find a plant ideotype for optimization of light absorption and canopy photosynthesis. Using a static functional structural plant model (FSPM), a range of different plant architectural characteristics was tested for two different seasons in order to find the optimal architecture with respect to light absorption and photosynthesis.

Methods

Simulations were performed with an FSPM of a greenhouse-grown tomato crop. Sensitivity analyses were carried out for leaf elevation angle, leaf phyllotaxis, leaflet angle, leaf shape, leaflet arrangement and internode length. From the results of this analysis two possible ideotypes were proposed. Four different vertical light distributions were also tested, while light absorption cumulated over the whole canopy was kept the same.

Key Results

Photosynthesis was augmented by 6 % in winter and reduced by 7 % in summer, when light absorption in the top part of the canopy was increased by 25 %, while not changing light absorption of the canopy as a whole. The measured plant structure was already optimal with respect to leaf elevation angle, leaflet angle and leaflet arrangement for both light absorption and photosynthesis while phyllotaxis had no effect. Increasing the length : width ratio of leaves by 1·5 or increasing internode length from 7 cm to 12 cm led to an increase of 6–10 % for light absorption and photosynthesis.

Conclusions

At high light intensities (summer) deeper penetration of light in the canopy improves crop photosynthesis, but not at low light intensities (winter). In particular, internode length and leaf shape affect the vertical distribution of light in the canopy. A new plant ideotype with more spacious canopy architecture due to long internodes and long and narrow leaves led to an increase in crop photosynthesis of up to 10 %.     

Technical communication: A simple and economically viable medium for the growth of Agrobacterium radiobacter for the production of d-amino acid

A simple and cost effective medium for the growth and d-amino acid production by Agrobacterium radiobacter from hydantoin is reported. The effectiveness of this medium is compared with other synthetic media.