Fresh Root Tissue Research Articles

Mass spectrometry imaging of small molecule in situ in Lepidium meyenii (Maca) using gold nanoparticles matrix

Lepidium meyenii Walp. (Maca), a functional food, has been used as a drug and food in Peru for more than two thousand years because Maca is rich in nutrition and rational in nutritional structure. Due to their uniform size and little interference in the low molecular weight region, Au nanoparticles (AuNPs) have been applied as a matrix to analyze the components of Maca extract and to visualize them of fresh root tissue in situ by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The result shows that imidazole alkaloids including Lepidiline A (1,3-dibenzyl-4,5-dimethylimidazolium chloride), Lepidiline B (1,3-dibenzyl-2,4,5-trimethylimidazolium chloride), Lepidiline C (3-benzyl-1-(3-methoxybenzyl)-4,5-dimethylimidazolium chloride), Lepidiline D (3-benzyl-1-(3-methoxybenzyl)-2,4,5-trimethylimidazolium chloride), 1, 3-dibenzyl-2-pentyl-4,5-dimethylimidazilium and 1, 3-dibenzyl-2-phenyl-4,5-dimethylimidazilium are the products of Maca after drying proess. Additionally, the distribution of amino acids, amide alkaloids, imidazolium alkaloids and saccharide in the upper, middle, and lower parts of Maca root tissue can be clearly visualized in situ with the synthesized AuNPs matrix by MALDI mass spectrometry imaging (MSI). The report provides a meaningful reference to study active components from natural product in situ.

English

An efficient protocol had been developed for the root culture of Luffa acutangula (L.) Roxb. The root and leaf explants from 21 day old in vitro raised seedlings were cultured on half strength Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of Indole-3-acetic acid(IAA), Indole-3-butyric acid (IBA) and Napthalene acetic acid (NAA). IBA at 1.0 mgl-1 combined with NAA (1.0 mgl-1) induced maximum percentage of rooting from leaf explants, under total dark condition. After 3 weeks, well established roots were separated. Fresh root tissue from the leaf explants and root tips from in vitro seedlings were subcultured in half strength MS liquid medium supplemented with different concentrations and combinations of IAA, IBA and NAA, under continuous agitation at 80 rpm under total dark condition. The biomass of root culture (derived from leaf explants) in the MS medium fortified with IBA(1.0 mgl-1), NAA(1.0mgl-1) and L-glutamine (20 mgl-1) was increased to 5.38 g FW and the biomass of root culture (derived from root tip) in the MS medium supplemented with IBA (0.5 mgl-1), NAA (1.0 mgl-1) and L- glutamine (20 mgl-1) was increased to 5.82 g FW after 7 weeks of culture.

Laterally resolved speciation of arsenic in roots of wheat and rice using fluorescence‐XANES imaging

• Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants. • We developed synchrotron-based fluorescence-X-ray absorption near-edge spectroscopy (fluorescence-XANES) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat (Triticum aestivum) and rice (Oryza sativa) exposed to 2 μM As(V) or As(III). • When exposed to As(V), the As was rapidly reduced to As(III) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As(III) was detected in any root tissues, because of the efficient formation of the As(III)-thiol complex - this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As(III) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As(III) is the major As species transported within the xylem and phloem. • Using fluorescence-XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.

Research on cadmium toxicity mechanism during maize germination

为了深入探讨重金属胁迫下植物重金属代谢过程及机理, 采用有一定重金属镉耐受能力的农作物玉米为试验材料, 综合研究了不同镉浓度(5~100 μmol·L^-1)及不同处理时间下玉米幼苗发芽、不同组织部位镉含量及分布、镉中毒前后液相色谱 质谱联用谱图(HPLC-MS)、核磁共振氢谱图(1H NMR)和总蛋白氨基酸含量。结果表明, 低于50 μmol·L^-1的镉浓度能促进玉米发芽, 高于此浓度可明显抑制发芽。镉在胚乳、根、茎、芽等新鲜组织部位的分布不均, 其分布情况为: 胚乳>根>茎>芽。HPLC-MS和¹H NMR分析结果表明, 玉米中镉以金属螯合剂(PC)形式络合。总蛋白氨基酸含量分析说明镉胁迫影响营养物质的吸收及合成。重金属镉在整个玉米幼苗中传输积累过程为: 大量镉吸附在胚乳中, 部分直接吸附在根表面; 部分镉以游离形式存在, 部分以植物金属螯合剂螯合形式存在; 镉在细胞中与各种蛋白作用, 在胞液、液泡、胞间连丝等细胞器间传递; 镉经根、茎传输到芽, 此过程主要受浓度梯度影响; 镉的传输过程很可能遵循顺浓度梯度的协助扩散过程, 试验证明了此过程的合理性。

Application of HR‐MAS NMR spectroscopy for studying chemotype variations of Withania somnifera (L.) Dunal

Withania somnifera (L.) Dunal (Solanaceae), commonly known as Ashwagandha, is one of the most valued Indian medicinal plants with a number of pharmaceutical and nutraceutical applications. Metabolic profiling has been performed by HR-MAS NMR spectroscopy on fresh leaf and root tissue specimens from four chemotypes of W. somnifera. The HR-MAS NMR spectroscopy of lyophilized defatted leaf tissue specimens clearly distinguishes resonances of medicinally important secondary metabolites (withaferin A and withanone) and its distinctive quantitative variability among the chemotypes. A total of 41 metabolites were identified from both the leaf and root tissues of the chemotypes. The presence of methanol in leaf and root tissues of W. somnifera was detected by HR-MAS NMR spectroscopy. Multivariate principal component analysis (PCA) on HR-MAS (1) H NMR spectra of leaves revealed clear variations in primary metabolites among the chemotypes. The results of the present study demonstrated an efficient method, which can be utilized for metabolite profiling of primary and secondary metabolites in medicinally important plants.

Establishment of adventitious root culture of Stevia rebaudiana Bertoni in a roller bottle system

Cultures of adventitious roots of Stevia rebaudiana (Bert.) Bertoni were performed in a roller bottle system for the production of both primary and secondary metabolites. Adventitious roots were induced from 1-cm-long root tip explants derived from in vitro regenerated plantlets on solid Murashige and Skoog (MS 1962) media supplemented with 10.7 μM of α-naphthaleneacetic acid. These cultures were successfully maintained in the same medium for 6 months with regular subcultures after 4 weeks. Thereafter, the roots were cut into 1.0- to 1.5-cm-long segments and transferred to the roller bottle system containing a fresh root tissue culture on liquid MS medium supplemented with 10.7 μM NAA. The apparatus consisted of a flask rolling system adjusted to 4g, and 3° of flask inclination. The roots were allowed to grow in the absence of light for adaptation and adventitious root formation. The best conditions for cultivation were investigated, considering culture volume (25 ml), culture period (4 weeks), salt concentrations in the nutrient medium (33%) and optimal initial inoculum (0.2 g) of S. rebaudiana roots. These results could give important information on how to improve the development of adventitious roots of S. rebaudiana for the production of primary and secondary metabolites.

English

  Fast-growing normal root culture of Vernonia amygdalina, a potent African medicinal plant was established from leaf explants of in vitro raised shoot induced from the stem nodal segments on murashige and skoog (MS) medium containing 0.5 mg l-1 6-benzylaminopurine (BA) in combination with 0.5 mg l-1  naphthalene acetic acid (NAA). In vitro raised plantlets were maintained on MS agar medium and sub cultured at 4 weeks interval and used as leaf explant source. Explants were cultured on half-strength MS medium supplemented with different concentrations of Indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) and NAA. Basal medium supplemented with IBA at 0.25 and 2.0 mg l-1 and under 16 photoperiod condition favoured induction of the longest root (2.7 ± 1.1 cm) and highest number of roots/explant (38.3 ± 1.1) respectively. After 6 weeks well established roots were separated. Fresh root tissue, in amount of a 100 mg were cultured in 50 ml full-strength MS liquid medium supplemented with 2.0 mg l-1 IBA and under continuous agitation (80 rpm). The biomass of root culture was increased to 2.1949 g after 5 weeks of culture. The root culture was maintained up to 6 weeks. The protocol developed in this study provides a basis for adventitious root induction and for further investigation of medicinally active constituents of this elite medicinal plant.   Key words: Vernonia amygdalina, nodal segment, leaf explant, root culture, medicinal plant, suspension culture.

Antileukemia activity from root cultures of Vernonia amygdalina.

Vernonia amygdalina, Del (Compositae) is an African medicinal plant well known for producing the anticancer agents’ vernodaline and vernolide. It grows wild under severe anthropogenic and environmental pressures. The roots are the principle material for herbal medicine. It is collected from the wild there is great variability in the quality and effectiveness of the root extracts. It is necessary to establish a fast-growing root culture and to test the extracts of cultured roots for activity against leukemia cells in vitro. Leaves were cultured on half-strength MS medium supplemented with different auxin types and concentrations. Basal medium supplemented with indole-3-butyric acid (IBA) at 2.0 mg/l favored induction of the highest number of roots/explant (38.3 ± 1.1). After six weeks well-established roots were separated. About 100 mg of fresh root tissue was cultured in 80 ml full-strength MS liquid medium supplemented with 2.0 mg/l IBA and under continuous agitation (80 rpm). The biomass of root cultures increases by 21 fold after 5 weeks of culture. Cold water, hot water and ethanol extracts from the in vitro cultured roots were prepared and tested for their antioxidant activity and efficacy against leukemia cells. All of the extracts showed significant antioxidant activity. All the extracts could kill the majority (50-75%) of abnormal cells among primary cells harvested from 3 patients with acute lymphoblastic leukemia (ALL) and 3 with acute myeloid leukemia (AML). DNA fragmentation patterns were detected within treated cells and inferred targeted cell death by apoptosis. The metabolites within the extracts may act as tumor inhibitors that promote apoptosis. Therefore in vitro root culture can be an alternative to collection from the wild, cultivation in the field or to chemical synthesis of anticancer agents. In addition the plant extracts may be used to supplement or replace established drugs treatments. Key words: Anticancer, natural products, plant extracts

Evaluation of Marigolds and Entomopathogenic Nematodes for Control of the Cabbage Maggot Delia radicum

The susceptibility of Delia radicum, cabbage maggot (CM), first instar larvae to fresh tissue extracts of two marigolds (Tagetes erecta and T. patula), the entomopathogenic nematode Steinernema feltiae, and a combination of them, was evaluated under laboratory and glasshouse conditions. In the laboratory, CM larvae were susceptible to marigold fresh tissue extracts; the root extracts were the most effective. Fresh root tissue extracts of non-flowering and flowering T. erecta caused 28% and 84% CM mortality, and T. patula caused 65% and 100% CM mortality, respectively. The nematodes caused up to 46% CM mortality at a concentration of 300 IJs/larva. In the glasshouse, up to 95% reduction of CM was achieved when cabbage plants, infected with CM eggs, were treated with fresh root extracts from either Tagetes species. Combination treatments with Tagetes and S. feltiae were also effective. Fresh tissue extracts of Tagetes spp. and S. feltiae show potential as control agents of D. radicum.

Characterization and Distribution of Phenolics in Carrot Cell Walls

Carrot cell walls have been shown to contain significant quantities of esterified p-hydroxybenzoic acid, which is presumed to be esterified to cell wall polymers. The purpose of this study was to investigate the distribution of p-hydroxybenzoic acid and related phenolics among carrot cell wall polysaccharides. Cell wall material was prepared from fresh carrot root tissues and extracted sequentially with water, imidazole, cyclohexane- trans-1,2-diamine- N, N, N', N'-tetraacetate, Na 2CO 3, and KOH (0.5, 1, and 4 M) to leave a cellulose-rich residue. The fractions were analyzed for their carbohydrate and phenolic acid components. Selected soluble fractions were subfractionated further by graded precipitation in ethanol. The majority of the polymer fractions comprised pectic polysaccharides, with varying quantities of neutral sugars (arabinose and galactose). Hemicellulosic polymers were generally found only in the strong alkali extracts (4 M KOH). p-OH-benzoic acid was the predominant phenolic ester and was associated with most fractions analyzed; p-OH-benzaldehyde was also detected in the fractions at much lower levels. Principal components analysis of the chemical data indicated that the p-OH-benzoic acid was associated predominantly with the branched pectic polysaccharides, in contrast to the p-OH-benzaldehyde. The possible roles and functional properties of these phenolics are discussed.

Chemical changes to nonaggregated particulate soil organic matter following grassland‐to‐woodland transition in a subtropical savanna

Encroachment of thorn woodlands into grasslands of southern Texas has resulted in greater aboveground and belowground biomass and greater soil organic carbon (SOC) stocks. Our previous studies showed that a large percentage of the SOC accrued under invading woody clusters was not stabilized within protective soil aggregates or on mineral‐surfaces. Here we evaluated lignin and cutin‐ and suberin‐derived substituted fatty acid (SFA) chemistry to determine if the accrual of nonaggregated particulate organic matter (POM) in woodlands was promoted by inherently greater recalcitrance of tissues from woody versus grass species, and if there was selective input of aboveground versus belowground plant carbon to POM. Woody clusters exhibited reduced concentrations of cutin‐derived SFA and cinnamyl phenols within surface litter compared to fresh aboveground plant material. However, root litter exhibited relatively minor changes in biopolymer chemistry compared to fresh root tissue, suggesting it was either more stable or was refreshed at a greater rate. Between 14 and 105 years of woody plant encroachment, SFA in free POM fractions appeared to be consistently derived from root material while SFA within intraaggregate POM were increasingly derived from cutin sources. In addition, the shift from herbaceous to woody input was accompanied by enrichment in the amount of cutin and suberin‐derived aliphatics with respect to lignin in both root and surface litter as well as nonaggregated POM. Woody plant encroachment at this site results in the rapid accrual of POM pools that are biochemically recalcitrant, providing a mechanism by which soil organic carbon can accumulate in this sandy soil system. Our results also lend further credence to the hypothesis that aliphatic biopolymers, particularly root‐derived suberin, are important components of long‐term soil organic carbon stabilization.

EFFECTIVENESS OF AUXIN INDUCED IN VITRO ROOT CULTURE IN CHICORY

An efficient protocol has been developed for the root culture of (Cichorium intybus L. cv. Focus), the leaf and hypocotyl explants from 25 days old in vitro raised seedlings were cultured on half-strength Murashige and Skoog (MS) medium supplemented with different concentrations and combinations of Indole-3-acetic acid (IAA), Indole-3-butyric acid (IBA), α-Napthalenacetic acid (NAA). 0.5 mg/l NAA and 0.1 mg/l IBA induced highest percentage of rooting from matured leaf explants, under total dark condition. After three weeks well established roots were separated. Fresh root tissue, in amount of 0.5 was subcultured in half-strength MS liquid medium supplemented with 0.2 mg/l NAA and 0.5 mg/l IBA, under continuous agitation at 110 rpm and total dark condition. The biomass of root culture was increased to 5.820 g after 6 weeks of culture. The root culture was maintained up to the 8 weeks.

Induction mechanism of 3-hydroxy-3-methylglutaryl-CoA reductase in potato tuber and sweet potato root tissues.

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC1.1.1.34), the key enzyme in isoprenoid biosynthesis, was purified from microsomes of potato tuber tissue, and a polyclonal antibody and two monoclonal antibodies against the purified enzyme were prepared. HMGR protein content was measured by immunotitration and radioimmunoassay using these antibodies. HMGR activity was very low in the fresh tissues of both potato tuber and sweet potato root. The activity in potato tuber was increased by cutting and further by additional fungal infection of the cut tissues. In sweet potato root tissue, the activity was scarcely increased after cutting alone, but was markedly increased by additional fungal infection or chemical treatment. The HMGR protein contents in both fresh potato tuber and sweet potato root tissues were also very low, and increased markedly in response to cutting and fungal infection. From these results, we proposed a hypothesis on the induction mechanism of HMGR after cutting and fungal infection in potato tuber and sweet potato root tissues.

Evaluation of a Core of the U.S. Capsicum Germplasm Collection for Reaction to the Northern Root-knot Nematode

Several species of root-knot nematodes [Meloidogyne incognita (Kofoid & White) Chitwood, M. arenaria (Neal) Chitwood, M. javanica (Treub) Chitwood, and M. hapla Chitwood] are major pests of peppers (Capsicum spp.) in the United States and worldwide. Resistance to M. incognita, M. arenaria, and M. javanica has been identified in several Capsicum accessions, but there are few reports of resistance to M. hapla. Therefore, we selected a 10% core (440 accessions) of the 14 available Capsicum spp. in the Capsicum germplasm collection (3,731 accessions) maintained by the U.S. Dept. of Agriculture (USDA), and evaluated this core for resistance to M. hapla in unreplicated greenhouse tests. The 11 best (most resistant) and the 3 worst (most susceptible) accessions identified in these unreplicated tests were re-evaluated in a replicated greenhouse test. Seven of these 11 “best” accessions (PI 357613, PI 357503, PI 439381, PI 297493, PI 430490, PI 267729, and PI 441676) exhibited root gall severity indices <5.0 (1 = no galls; 9 = more than 80% of the root system covered with galls) in the replicated test, and each of these indices was significantly lower than the indices of the “worst” accessions and susceptible controls. Although a gall index <5.0 indicates a moderate level of resistance, more than 3000 M. hapla eggs were extracted per gram of fresh root tissue and the reproductive index was >1.0 for each of these accessions. These observations suggest that the most resistant accessions tested are somewhat susceptible to M. hapla. The results of our evaluation of a core of the USDA Capsicum germplasm collection demonstrates clearly that there is significant genetic variability within the overall collection for M. hapla resistance. Additionally, these results identify portions of the collection where future evaluations for M. hapla resistance should be focused. For example, the origin of the two most promising C. annuum accessions (PI 357613 and PI 357503) in the core was Yugoslavia. Thus, additional accessions from this temperate region of the world should receive priority attention in any effort to identify better sources of resistance in C. annuum to M. hapla.

Nitrogen Fertilization to Maximize Carrot Yield and Quality on a Sandy Soil

Nitrogen is required for successful carrot production on sandy soils of the southeastern United States, yet carrot growers often apply N in amounts exceeding university recommendations. Excessive fertilization is practiced to compensate for losses of N from leaching and because some growers believe that high rates of fertilization improve vegetable quality. Carrots (Daucus carota L.) were grown in three plantings during Winter 1994–95 in Gainesville, Fla., to test the effects of N fertilization on yield and quality. Yield increased with N fertilization but the effect of N rate depended on planting date; 150 kg·ha–1 N maximized yield for November and December plantings but 180 kg·ha–1 N was sufficient for the January planting. Concentration of total alcohol-soluble sugar was maximized at 45 mg·g–1 fresh root with 140 kg·ha–1 N for `Choctaw' carrots, whereas sugar concentration of `Scarlet Nantes' roots was not affected by N fertilization. Carrot root carotenoid concentration was maximized at 55 mg·kg–1 fresh root tissue with 160 kg·ha–1 N. Generally, those N fertilization rates that maximized carrot root yield also maximized carrot quality as determined by sugar and carotenoid concentrations.

External and internal root colonization of lodgepole pine seedlings by two growth-promotingBacillusstrains originated from different root microsites

Root colonization and in vitro carbon substrate utilization by two seedling growth-promoting Bacillus strains that originated from different root microsites were studied in greenhouse and growth chamber experiments. Strain L6, identified as Bacillus polymyxa, was previously isolated from rhizosphere soil containing roots of pasture plants, and Pw-2, tentatively identified also as B. polymyxa, was isolated from within surface-sterilized lodgepole pine (Pinus contorta var. latifolia (Dougl.) Engelm.) roots. Rifamycin-resistant strains derived spontaneously from wild-type strains L6 and Pw-2, designated strain L6-16R and Pw-2R, respectively, were used to monitor lodgepole pine root colonization in a closed tube assay system. Three-week-old pine seedlings were inoculated with 105colony-forming units (cfu) of strain Pw-2R or 106 cfu of strain L6-16R, and external and internal root colonization was assessed 2 and 4 weeks later. Strains L6-16R and Pw-2R were both recovered from pine rhizosphere samples with > 5 × 107 cfu/g fresh root tissue 2 weeks after inoculation, but neither strain was detected in the root interior. When root colonization was assessed 4 weeks after inoculation, the rhizosphere populations of both strains had declined slightly to between 5 × 106and 5 × 107 cfu/g fresh root tissue, but strain Pw-2R was also detected within root tissues with 105 cfu/g fresh root tissue. Lateral root formation was abundant 4 weeks after inoculation and may have facilitated colonization of internal root tissues by strain Pw-2R. Both strains possessed pectolytic activity, although differences between the strains were detected in in vitro substrate utilization capabilities using BIOLOG assays. These differences may be related to their abilities to colonize internal root tissues. On the basis of our results, we hypothesize that internal root colonization by Bacillus strains is not a random event and that root-endophytic Bacillus strains possess specific physiological and (or) biochemical characteristics that facilitate colonization of internal root tissues.Key words: Bacillus, PGPR, rhizosphere, endophytes, colonization.

Phenol removal by Eichhornia crassipes in the presence of trace metals

The removal of phenols in the presence of copper and zinc by the aquatic weed, Eichhornia crassipes was investigated in order to assess its ability to clean up industrial wastewaters. Results indicate that Eichhornia has tremendous capacity to absorb phenolic compounds as well as Cu and Zn simultaneously from test solutions containing these substances. The presence of Cu or Zn resulted in decreased phenol uptake during the first 0.5 d, while the presence of Cu and Zn in combination resulted in higher phenol uptake. After 1 d exposure, however, little or no differences could be discerned. Similarly, absorption of Cu and Zn in the presence of phenols did not seem to be adversely affected by different combinations of Cu/Zn concentrations. In fact, some synergistic effect could be detected between Cu and Zn absorption by Eichhornia crassipes. Bioassays involving filtered Eichhornia root extract indicated that phenol was also removed by the aqueous root extracts indicating that cellular constituents of roots were involved in the process. The corresponding K m and V max for the enzyme-like substance were 0.58 and 8.97 mM phenol/h/g fresh root tissue, respectively.

Changes in α- and ß-amylase during Storage of Sweetpotato Lines with Varying Starch Hydrolysis Potential

Staple-type lines of sweetpotato [Ipomoea batatus (L.) Lam.] do not sweeten significantly upon cooking as compared to the traditional-type lines. Four lines exhibiting distinct differences in sweetness after cooking were evaluated for changes in α- and ß-amylase activity and reducing sugars (by HPLC) at harvest, after curing, and at intervals during 180 days of storage. The traditional cultivar `Jewel' and staple-type line `Sumor' displayed high a- and ß-amylase activities, which rose from low levels at harvest to peak levels ≈ 90 days into the storage period. Staple-type lines `99' and `86' displayed significantly lower a- and ß-amylase activities. By using polyclonal sweetpotato ß-amylase antibody and western blot following native- and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it was confirmed that a lower level of ß-amylase synthesis existed in `99' and `86'. Quantitatively, `Jewel', `Sumor', and an additional staple-type line, `HiDry', had 361,374, and 365 μg ß-amylase protein per gram of fresh storage root tissue, respectively, while `99' and `86' possessed <60 and 12 μg·g-1, respectively. In raw roots, individual (glucose, fructose, and sucrose) and total sugar concentrations were significantly higher in `Jewel' than in `Sumor', `99', or `86'. Only trace amounts of maltose were found in raw roots of any line. Sucrose, glucose, and fructose concentrations decreased with baking in all lines except `86', in which they increased. There was substantial maltose produced by baking `Jewel' and `Sumor', but only trace amounts found in baked `99' and `86'. Sweetpotato germplasm can be separated into four general classes based on initial sugar concentration and changes during cooking: 1) low sugars/low starch hydrolysis, 2) low sugars/high starch hydrolysis, 3) high sugars/low starch hydrolysis, and 4) high sugars/high starch hydrolysis. At least two mechanisms may confer the lack of starch hydrolysis and subsequent sweetening in staple-type sweetpotato: 1) inhibition of ß-amylase synthesis, and 2) a nonenzyme mediated mechanism.

Caffeic Acid Identified as an Inhibitory Compound in Asparagus Root Filtrate

A potential allelochemical was isolated and identified from methanol extracts of asparagus (Asparagus officinalis L.) fresh root tissue. Fractions were collected by cellulose column chromatography and tested for inhibition by an asparagus seed germination bioassay. The fraction showing the greatest inhibition contained caffeic acid, as identified by melting point, thin-layer chromatography, and infrared spectrum analysis. Seed germination bioassays and greenhouse pot tests showed depression of seedling emergence when asparagus seeds were exposed to various dosages of crude filtrate, a methanol extract from crude filtrate, and caffeic acid.

Isolation and characterization of phytotoxic compounds from asparagus (Asparagus officinalis L.) roots

Potential allelochemicals from aqueous extracts of dried asparagus (Asparagus officinalis L.) roots were isolated and characterized. Active fractions separated by HPLC included ferulic, isoferulic, malic, citric, and fumaric acids. Soxhlet extraction of the residues also produced phytotoxic caffeic acid. Although none of these compounds, when applied singly, was active enough to account for the phytotoxicity of asparagus extracts, their combined effect might be additive or synergistic. An extract from lyophilized fresh root tissues contained a fraction that was one order of magnitude more toxic than any compound obtained from the dried roots. The most active component was isolated by TLC and characterized by [(1)H]NMR as methylenedioxycinnamic acid (MDCA). This compound provided severe inhibition of curly cress (Lepidium sativum L.) root and shoot growth at concentrations of 25 ppm or above.