Multivariate analysis and the choice of parents for hybridization in Okra (Abelmoschus esculentus (L.) Moench)

Summary Thirty okra genotypes of diverse eco-geographical origin were grown in single-row plots in a randomised complete block design. The data collected on 14 characters were subjected to analysis of variance. By multivariate analysis (Mahalanobis D² technique), the genetic divergence among the genotypes were quantitatively measured. The genotypes were grouped into five clusters by this technique. There was no relationship between clustering pattern and eco-geographic distribution. The effects of genetic divergence on the choice of parental stock in hybridization was discussed.     

Numerical Analysis of Variation Among Accessions of Okra [Abelmoschus esculentus (L.) Moench], Malvaceae

Thirty quantitative and qualitative characters were observedon 20 accessions of okra which consisted of 19 accessions fromdifferent geographical areas of Nigeria and one accession fromIndia. Principal Component Analysis (PCA) and Single LinkageCluster Analysis (SLCA) were employed to analyse the variationpatterns in these accessions. The first three principal componentsaccounted for 49.94% of the total variation while the firstfive axes accounted for 65.7% SLCA summarized the relationshipsamong the accessions at various levels of similarity into adendrogram, while the accessions were sorted into six distinctgroups by the FASTCLUS technique and the mean percentage similaritybetween some groups suggested some degree of phenetic resemblance. Abelmoschus esculentus, okra, variation, principal component analysis, cluster analysis     

Activities of Enzymes of Carbohydrate Metabolism during Development of Okra [Abelmoschus esculentus (L.) Moench] Seed

Changes in activity levels of important enzymes of carbohydratemetabolism (and ß-amylases, sucrose synthetase, acidinvertase, acid phosphatase, glucose phosphate isomerase, aldolase,phosphofructokinase and pyruvate kinase) during seed developmentwere determined. Changes in the activities of these enzymesand their functional significance in developing seeds are described.A close correlation was found between the stage of maximum carbohydrateoxidation and the accumulation of reserve materials in the developingseeds. ¹Present address: School of Agriculture and Forestry, Universityof Melbourne, Parkvilie 3052, Victoria, Australia. ²Present address: School of Botany, University of Melbourne,Parkville 3052, Victoria, Australia. (Received October 8, 1982; Accepted January 10, 1983)     

Effect of Chlorflurenol on Sex Expression, Fruit Set and Yield in Abelmoschus esculentus (L. ) Moench

Plants of Abelmoschus esculentus were given a single foliarspray of chlorflurenol at 1, 10, 100, and1000 parts 10^–6by a hand atomizer. Chlorflurenol increased the number of flowersat all the concentrations used except 1000 parts 10^–6where a drastic reduction was noticed. Various stages of suppressionin the growth and reduction in number of stamens were seen inflowers of treated plants. Formation of stamenless flowers,i.e. pistillate flowers, was a striking influence of chlorflurenol.Chlorflurenol also increased fruit set, and therefore yield,up to 100 parts 10^–6 but drastically reduced both at 1000parts 10^–6. Parthenocarpic fruit set was induced by chlorflurenolonly at 100 and 1000 parts 10^–6.     

Measurement and classification of genetic diversity in okra (Abelmoschus esculentus)

Eighteen accessions of okra of diverse ecological background were evaluated for genetic variability through the techniques of coefficient of racial likeness (CRL) and principal coordinate analysis (PCO). The variation patterns among the accessions were classified by using the techniques of metroglyph analysis and single-linkage cluster analysis. CRL and PCO produced similar results on the diversity of the accessions but the grouping of the accessions by metroglyph analysis and SLCA produced different results. The usefulness of metroglyph analysis depends on the amount of variation accounted for by the two principal characters on which the two co-ordinate axes are constructed. The techniques are compared.     

Biochar and Arbuscular mycorrhizal fungi mediated enhanced drought tolerance in Okra (Abelmoschus esculentus) plant growth,root morphological traits and physiological properties

Drought is a major abiotic factor limiting plant growth and crop production. There is limited information on effect of interaction between biochar and Arbuscular mycorrhizal fungi (AMF) on okra growth, root morphological traits and soil enzyme activities under drought stress. We studied the influence of biochar and AMF on the growth of Okra (Abelmoschus esculentus) in pot experiments in a net house under drought condition. The results showed that the biochar treatment significantly increased plant growth (the plant height by 14.2%, root dry weight by 30.0%) and root morphological traits (projected area by 22.3% and root diameter by 22.7%) under drought stress. In drought stress, biochar treatment significantly enhanced the chlorophyll ‘a’ content by 32.7%, the AMF spore number by 22.8% and the microbial biomass as compared to the control. Plant growth parameters such as plant height, shoot and root dry weights significantly increased by AMF alone, by 16.6%, 21.0% and 40.0% respectively under drought condition. Other plant biometrics viz: the total root length, the root volume, the projected area and root diameter improved significantly with the application of AMF alone by 38.3%, 60.0%,16.8% and 15.9% respectively as compared with control. Compared to the control, AMF treatment alone significantly enhanced the total chlorophyll content by 36.6%, the AMF spore number by 39.0% and the microbial biomass by 29.0% under drought condition. However, the highest values of plant growth parameters (plant height, shoot dry weight, root dry weight) and root morphological traits (the total root length, root volume, projected area, root surface area) were observed in the combined treatment of biochar and AMF treatment viz: 31.9%, 34.2%, 60.0% and 68.6%, 66.6%, 45.5%, 41.8%, respectively compared to the control under drought stress. The nitrogen content, total chlorophyll content and microbial biomass increased over un-inoculated control. The soil enzymes; alkaline phosphatase, dehydrogenase and fluorescein diacetate enzyme activities significantly increased in the combined treatment by 55.8%, 68.7% and 69.5%, respectively as compared to the control under drought stress. We conclude that biochar and AMF together is potentially beneficial for cultivation of okra in drought stress conditions.     

Extraction of geminiviral DNA from a highly mucilaginous plant (Abelmoschus esculentus)

A protocol is described for the extraction of geminiviral DNA from bhendi yellow vein mosaic virus-infectedAbelmoschus esculentus (known as bhendi or okra) containing high amounts of mucilage and other phenolic compounds. This method involves extraction with a buffer containing sodium citrate at pH 6 and PEG precipitation of the virus followed by alkali lysis. The extraction buffer eliminates the mucilage and other polyphenols, PEG precipitates the viral particles and DNA and the alkali lysis enriches the replicative forms of the viral DNA. The extracted DNA could be digested with restriction enzymes and cloned without any interference from chromosomal DNA. The quality of the DNA extracted by this method was compared to three other common plant DNA extraction protocols and was found superior. This method was used for PCR amplification and cloning of the 2.7 kbp DNA-A of BYVMV.     

Effect of Number of Photoperiodic Cycles on Flowering and Fruiting in Early and Late Varieties of Okra (Abelmoschus esculentus (L.) Moench.)

Early and late varieties of the short day plant, Abelmoschusesculentus (L.) Moench. (= Hibiscus esculentus L.), were subjectedto various numbers of short days (SD; 10 h natural daylight)before transfer to 16 h long days. Short day treatments werestarted at the time of cotyledon release following seed germination,and their effects on the induction and development of flowersand fruits were recorded. While early okra required 6 SD cyclesfor the induction of flowering in all plants, late okra required14. However, both varieties needed more than 20 SD cycles forflower opening; flower buds produced by plants given fewer SDcycles abscinded with little or no development. In both varieties,the number of flower buds produced on each plant increased asthe number of short day cycles was increased from 5 to 20; flowerbuds were initiated at more axillary bud sites on the main stem.Three fruits were formed on each plant of both varieties subjectedto more than 30 SD cycles but, while the last formed fruit abscindedwithout development, the other two developed and became filledwith seeds. However, the greatest yield in fruit dry weightwas from plants kept under SD throughout and also in late okraplants given 55 SD. In general, the total number of seeds perplant increased as a larger number of SD cycles were imposed.     

An unstable gene controlling developmental variegation in okra (Abelmoschus esculentus (L.) Moench)

Summary Genetic studies on radiation-induced chlorina and variegated mutants of okra (Abelmoschus esculentus (L.) Moench) revealed the existence of an unstable gene. The normal green color of the leaves is controlled by duplicate genes C₁ and C₂, either of which produces the green colour. The chlorina plants are C ₁ C ₁ C ₂ C ₂. The allele c ₁ ^v is dominant to both C ₁ and C ₂ but is unstable. The homozygote c ₁ ^v c ₁ ^v c ₂ c ₂ is a normal green while the heterozygote c _i ^v c ₁ c ₂ c ₂ has a variegated phenotype as a result of the mutation of c ₁ ^v to c ₁ during development. In green plants with a c ₁ ^v c{sh1/v}c ₂ c ₂ genotype, the autonomous mutation of one of the c ₁ ^v alleles to c ₁ may take place at the pre-meiotic stage. In the variegated genotype (c ₁ ^v c ₁ c ₂ c ₂), the mutation of c ₁ to c ₁ ^v may take place in early ontogeny, thus producing green plants. The allele C ₁, when associated with c ₁ ^v in a heterozygous condition, mutates to c ₁ at the pre-meiotic stage even in the presence of the allele C ₂.     

Adhesion of water stressed Helicobacter pylori to abiotic surfaces

AIM: The main aim of this work was to study and compare the adhesion of water exposed Helicobacter pylori to six different substrata and correlate any changes in morphology, physiology, ability to form aggregates and cultivability when in the planktonic or in the sessile phase. METHODS AND RESULTS: The number of total cells adhered for different water exposure times and modifications in the cell shape were evaluated using epifluorescence and scanning electron microscopy, and physiology assessed using Syto9 and propidium iodide (PI) cellular uptake. All abiotic surfaces were rapidly colonized by H. pylori, and colonization appeared to reach a steady state after 96 h with levels ranging from 2.3 x 10(6) to 3.6 x 10(6) total cells cm(-2). Cell morphology was largely dependent on the support material, with spiral bacteria, associated with the infectious form of H. pylori, subsisting in a higher percentage on nonpolymeric substrata. Also, sessile bacteria were generally able to retain the spiral shape for longer when compared with planktonic bacteria, which became coccoid more quickly. The formation of large aggregates, which may act as a protection mechanism against the negative impact of the stressful external environmental conditions, was mostly observed on the surface of copper coupons. However, Syto9 and PI staining indicates that most of H. pylori attached to copper or SS304 have a compromised cell membrane after only 48 h. Cultivability methods were only able to detect the bacteria up to the 2 h exposure-time and at very low levels (up to 500 CFU cm(-2)). CONCLUSIONS: The fact that the pathogen is able to adhere, retain the spiral morphology for longer and form large aggregates when attached to different plumbing materials appeared to point to pipe materials in general, and copper plumbing in particular, as a possible reservoir of virulent H. pylori in water distribution systems. However, the Syto9/PI staining results and cultivability methods indicate that the attached H. pylori cells quickly enter in a nonviable physiological state. SIGNIFICANCE AND IMPACT OF THE STUDY: This represents the first study of H. pylori behaviour in water-exposed abiotic surfaces. It suggests that co-aggregation with the autochthonous heterotrophic consortia present in water is necessary for a longer survival of the pathogen in biofilms associated to drinking water systems.     

Antiadhesive property of microalgal polysaccharide extract on the binding of Helicobacter pylori to gastric mucin

The emergence of antibiotic-resistant Helicobacter pylori is of concern in the treatment of H. pylori-associated gastroduodenal diseases. As the organism was reported to bind gastric mucin, we used porcine gastric mucin as substrate to assess the antiadhesive property of polysaccharides derived from Spirulina (PS), a commercially available microalga, against the binding of H. pylori to gastric mucin. Results show that polysaccharides prevented H. pylori from binding to gastric mucin optimally at pH 2.0, without affecting the viability of either bacteria or gastric epithelial cells, thus favouring its antiadhesive action in a gastric environment. Using ligand overlay analysis, polysaccharide was demonstrated to bind H. pylori alkyl hydroperoxide reductase (AhpC) and urease, which have shown here to possess mucin-binding activity. An in vivo study demonstrated that bacteria load was reduced by >90% in BALB/c mice treated with either Spirulina or polysaccharides. It is thus suggested that polysaccharides may function as a potential antiadhesive agent against H. pylori colonization of gastric mucin.     

Lectin of Abelmoschus esculentus (okra) promotes selective antitumor effects in human breast cancer cells

The anti-tumor effects of a newly-discovered lectin, isolated from okra, Abelmoschus esculentus (AEL), were investigated in human breast cancer (MCF7) and skin fibroblast (CCD-1059 sk) cells. AEL induced significant cell growth inhibition (63 %) in MCF7 cells. The expression of pro-apoptotic caspase-3, caspase-9, and p21 genes was increased in MCF7 cells treated with AEL, compared to those treated with controls. In addition, AEL treatment increased the Bax/Bcl-2 ratio in MCF7 cells. Flow cytometry also indicated that cell death (72 %) predominantly occurred through apoptosis. Thus, AEL in its native form promotes selective antitumor effects in human breast cancer cells and may represent a potential therapeutic to combat human breast cancer.     

黄秋葵查尔酮合成酶基因AeCHS的克隆与表达分析

采用同源序列克隆和RT-PCR技术,首次克隆得到黄秋葵查尔酮合成酶基因(CHS)cDNA全长序列。序列分析表明,该序列全长1175 bp,包括一个1170 bp的完整ORF,编码389个氨基酸,命名为AeCHS。生物信息学分析表明,本研究所获得的AeCHS氨基酸序列与同科植物黄蜀葵和陆地棉的同源性较高,分别达99.23%和97.44%,AeCHS推断的氨基酸序列含有CHS蛋白的标签序列GFGPG以及4个保守活性位点Cys164、Phe215、His303、Asn336。实时荧光定量PCR分析黄秋葵果实、花、叶片不同发育时期AeCHS基因的表达量,结果表明AeCHS基因在上述植物材料中表现出不同的表达模式:花>果实>叶片,具体到不同植物组织,AeCHS基因在生长6 d的果实、盛开的花朵以及植株顶端第4片叶子中的表达量较高。     

Rhizosphere mycoflora of healthy and yellow vein mosaic virus infected okra (Abelmoschus esculentus) plants.

Investigations on the rhizosphere mycoflora of healthy and virus (YVMV) infected okra plants showed a higher fungal population in the rhizosphere of healthy plants at preflowering and post-flowering stages than in that of diseased ones. Maximum population was observed during flowering both in healthy and diseased plant rhizosphere as well as in non-rhizosphere soil. However, virus infected plants showed a higher population at the flowering stage than healthy ones. The quantitative differences in the rhizosphere of healthy and diseased plants during flowering seem to be due to a change in C/N ratio and amino acids. The drastic reduction in diseased plant rhizospheres during the post-flowering stage may be due to either change in C/N ratio unfavourable to mycoflora or production of some toxic substances inhibiting multiplication of the mycoflora.     

Influence of oral Helicobacter pylori on the success of eradication therapy against gastric Helicobacter pylori

Background. The goal of this study was to see whether Helicobacter pylori ( H. pylori ) in the oral cavity might adversely affect the outcome of eradication therapy for gastric H. pylori.
Materials and Methods. Forty-seven patients (36 males, 11 females) with gastric H. pylori infection were enrolled in this study. Gastric H. pylori infection was confirmed by both immunohistological staining with anti- H. pylori antibody and bacterial culture of biopsy specimens. The therapeutic regimen consisted of 30 mg/day lansoprazole, 750 mg/day metronidazole, and 400 mg/day clarithromycin administered for 2 weeks. A fragment of the H. pylori urease gene was amplified by nested PCR for DNA extracted from saliva and dental plaque from the same patients. We examined the correlation between the gastric eradication success rate and the prevalence of H. pylori in the oral cavity as determined by PCR before and after the eradication therapy.
Results. The eradication success rate was significantly lower in the oral H. pylori -positive cases (12/23, 52.1%) than in the negative cases (22/24, 91.6%) at 4 weeks after the therapy (p = .0028). Two years later, only 16 of the 23 (69.5%) oral H. pylori -positive cases were disease-free, as compared to 23 of the 24 (95.8%) oral H. pylori -negative cases (p = .018).
Conclusions. H. pylori in the oral cavity affected the outcome of eradication therapy and was associated with a recurrence of gastric infection. We recommend that oral H. pylori should be examined by nested PCR and, if positive, should be considered a causal factor in refractory or recurrent cases.     

Selective and effective bactericidal activity of the cobalt (II) cation against Helicobacter pylori

BACKGROUND: Although the anti-Helicobacter pylori activity of bismuth is well established, the therapeutic potential of other metal ions against the organism is not known. MATERIALS AND METHODS: We measured the minimum inhibitory concentrations of a series of metal ions, including several cobalt (II) compounds against four type strains and seven clinical isolates of H. pylori using three standard broth culture media and a defined medium. Other intestinal bacteria were also investigated for specificity of action. RESULTS: Cobalt chloride had marked activity against H. pylori (minimum inhibitory concentration range was 0.03-1.0 mg/l). The effect was specific because other transition metals had no effect and other intestinal bacteria were not affected by cobalt chloride. Activity was attributable to free cobalt ions as ligands inhibited activity in proportion to their affinity for the ions. Inhibition of cobalt activity was also observed in the presence of nickel, in a dose dependent fashion. However, cobalt activity was not directed towards the nickel-dependent urease enzyme because its effect was similar in wild-type and urease negative mutant strains of H. pylori. Finally, the viability of H. pylori was reduced at the same rate with 2 mg/l cobalt as with 1 mg/l amoxicillin. CONCLUSIONS: Cobalt competes for nickel in its acquisition by H. pylori, but mediates toxicity in a nonurease dependent fashion. As cobalt MIC is similar to some antibiotics and 10 to a hundred times lower than for bismuth, cobalt may represent an effective form of therapy for H. pylori infection.     

Successful Development of Air-Dried Microplates (HP-Plates) for Susceptibility Testing against Helicobacter pylori Isolates

We have successfully developed and evaluated a new susceptibility testing procedure against Helicobacter pylori strains using air-dried microplates “HP-Plates” containing eight serially-diluted anti-H. pylori agents. HP-Plate wells were reconstituted by the inoculation of 100 μl of H. pylori cell suspensions. After incubation at 37 C for 48 hr under humidified microaerophilic conditions, HP-Plates were read visually with a circular mirror. We investigated the within-day reproducibility tests of HP-Plates using the six quality control (QC) strains we proposed. Of the 20 testings, determining the minimum inhibitory concentrations (MICs) of all the QC strains fell within ± 1 log2 dilution ranges. When 200 clinical isolates were tested with HP-Plates and compared with the results obtained with the modified broth macrodilution method of NCCLS, more than 90% of the MICs also fell within ±1 log2 dilution ranges. We concluded that the HP-Plate susceptibility test method is a practical and easily applicable alternative of susceptibility testing for clinical microbiology laboratories in determining the MICs of H. pylori isolates.     

Antimicrobial activity of essential oils against Helicobacter pylori

Background. Helicobacter pylori is an important pathogen responsible for gastroduodenal diseases in humans. Although the eradication of H. pylori using antibiotics often improves gastroduodenal diseases, resistance to the antibiotics is emerging. Materials and Methods. The antimicrobial effect of essential oils and the development of resistance to the essential oils were evaluated in vitro and in vivo. Results. Thirteen essential oils used in this study completely inhibited the growth of H. pylori in vitro at a concentration of 0.1% (v/v). Cymbopogon citratus (lemongrass) and Lippia citriodora (lemon verbena) were bactericidal against H. pylori at 0.01% at pH 4.0 and 5.0. Resistance to lemongrass did not develop even after 10 sequential passages, whereas resistance to clarithromycin developed under the same conditions. In in vivo studies, the density of H. pylori in the stomach of mice treated with lemongrass was significantly reduced compared with untreated mice. Conclusions. These results demonstrate that the essential oils are bactericidal against H. pylori without the development of acquired resistance, suggesting that essential oils may have potential as new and safe agents for inclusion in anti‐H. pylori regimens.