Molecular characterization and transcriptional analysis of VrWOX genes in mungbean Vigna radiate (L.) Wilczek / 生物工程学报

WUSCHEL-related homebox (WOX) gene family is a type of plant specific transcription factor, and belongs to the homeobox (HB) transcription factor superfamily. WOX genes play an important role in plant development, such as stem cell regulation and reproductive progress, and have been identified in many plant species. However, the information of mungbean VrWOX genes is limited. In this study, we identified 42 VrWOX genes in mungbean genome using Arabidopsis AtWOX genes as BLAST queries. VrWOX genes are unevenly distributed on 11 mungbean chromosomes, and chromosome 7 contains the most VrWOX genes. VrWOX genes are classified into three subgroups, the ancient group, the intermediate group and the modern/WUSCHEL group, which contains 19, 12 and 11 VrWOX members, respectively. Intraspecific synteny analysis revealed 12 VrWOX duplicated gene pairs in mungbean. Mungbean and Arabidopsis thaliana have 15 orthologous genes, and mungbean and Phaseolus vulgaris have 22 orthologous genes, respectively. The gene structure and conserved motif are different among VrWOX genes, indicating their functional diversity. The promoter regions of VrWOX genes contain different number and type of cis-acting elements, and VrWOX genes show distinct expression levels in eight mungbean tissues. Our study investigated the bioinformation and expression profiles of VrWOX genes, and provided essential information for further functional characterization of VrWOX genes.

Genetic diversity and marker trait association for yellow mosaic virus disease in green gram, Vigna radiata (L.) Wilczek

Yellow mosaic virus (YMV) disease is known to cause severe damage in green gram in terms of yield loss. As the resistance is often governed by recessive genes, introgression of such resistance faces some difficulty. DNA molecular markers are reported to be effective in this process. However, validation of such markers is important. Here, we have made an attempt to validate DNA markers associated with YMV disease resistance gene from a diverse group of 26 green gram genotypes. A total of 19 molecular markers were used to assess the susceptibility or resistance against YMV disease. Results show that among the amplified 31 alleles, 21 were polymorphic, with a mean of 1.1.0 per locus. The polymorphism information content (PIC) values ranged from 0.32 to 0.80. Only five markers exhibited higher PIC value (>6.0) and were revealed to be polymorphic, suggesting its utility in marker assisted selection for breeding YMV resistant genotypes in greengram. Dice dissimilarity coefficient among the genotypes exhibited a range of 0.07 to 1.0 which show a wide genetic variation among the genotypes for YMV tolerance. Neighbor-joining cluster analysis has grouped 26 green gram genotypes into 4 main clusters which revealed the existence of genetic dissimilarities among the genotypes. The genotypes AUGG 6, VBN (Gg) 2 and CO (Gg) 8 carried the positive alleles for YMV disease resistance and the allele for susceptibility were found in the genotypes AUGG 12, AUGG 15, AUGG 17 and AUGG 19. Single marker analysis indicated that there was correlation between the markers and the disease reaction in the field with exceptions. The findings revealed that the SSR markers CEDG180 and YR4 could be used to screen germplasm in order to discriminate the YMV resistant genotypes from the susceptible genotypes in marker assisted selection.

Effect of potassium application on yield and quality of green gram (Vigna radiata L.) on coarse textured soils of southern Haryana

Crops need large quantity of potassium for enhancing their yield as well as quality. Pulses are important crops grown in India but their productivity is low. Among production inputs, recommendations for N and P fertilizers are made in most states with no K application resulting in imbalanced nutrient supply and lower crop yields.To quantify optimum dose for green gram ( Vigna radiata L.), a series of field experiments were conducted at Regional Research Station, CCS HAU, Bawal, Haryana, to assess the response of green gram to fertilizer potassium on coarse textured (Typic Haplustepts) soils of southern Haryana. After completion of research trials, crop was tested on farmer’s field through demonstrations and on farm trials (OFTs) to evaluate the response and adoptability of green gram as per the fertilizer potassium doses concluded in research experiment. Five levels of fertilizer potassium (0, 10, 20, 30 and 40 kg K2O ha-1) were evaluated for the response of green gram in randomized block design replicated thrice. The results of research trials revealed that the yield, protein content and growth parameters of green gram increased significantly with the application of fertilizer potassium @20 kg K2O ha-1. Significantly higher yield of green gram was recorded (5.87, 16.29, 19.23 and 22.36 %) due to application of 10, 20, 30 and 40 kg K2O ha-1, respectively over control. The total K uptake by green gram increased significantly with the incremental doses of potassium application which helped to prevent the depletion of available soil K and build-up its content in the soil. The mean K use efficiency varied from 38.30 to 54.15 and maximum (54.15 %) was recorded with the application of 20 kg K2O ha-1. The benefit cost ratio was also increased with the application of potassium and reflected in terms of additional returns per rupee (Rs. 10.94, 15.63, 12.17 and 10.72) invested on application of K @ 10, 20, 30 and 40 kg K2O ha-1, respectively. The farmer’s field trial results with 0 and 20 kg K2O ha-1 revealed that application of 20 kg K2O ha-1 increased the yield of green gram by 10.87% over control.

Effects of exogenous γ-Aminobutyric acid on the regulation of respiration and protein expression in germinating seeds of mungbean (Vigna radiata) under salt conditions

BACKGROUND: γ-Aminobutyric acid (GABA) bypasses the TCA cycle via GABA shunt, suggesting a relationship with respiration. However, little is known about its role in seed germination under salt conditions. RESULTS: In this study, exogenous GABA was shown to have almost no influence on mungbean seed germination, except 0.1 mM at 10 h, while it completely alleviated the inhibition of germination by salt treatment. Seed respiration was significantly inhibited by 0.1 and 0.5 mM GABA, but was evidently enhanced under salt treatment, whereas both were promoted by 1 mM GABA alone or with salt treatment. Mitochondrial respiration also showed a similar trend at 0.1 mM GABA. Moreover, proteomic analysis further showed that 43 annotated proteins were affected by exogenous GABA, even 0.1 mM under salt treatment, including complexes of the mitochondrial respiratory chain. CONCLUSIONS: Our study provides new evidence that GABA may act as a signal molecule in regulating respiration of mungbean seed germination in response to salt stress.

Identification of suitable mungbean genotypes for hilly terrains of India using GGE and AMMI biplot approaches

Aim: The present investigation was conducted to approximate the magnitude of genotype × environment interaction effects in mungbean crop and to identify suitable genotypes for northern hilly terrain of India. Methodology: Thirty one promising mungbean genotypes were evaluated in three diverse environments, viz., Srinagar, Berthin and Imphal of northern hilly terrains of India. The individual genotype was planted in 5 rows of 4m length in 3 replications in randomized block design. The statistical analysis was done for Additive Main effect and Multiplicative Interaction (AMMI) and genotype main effect plus genotype-by-environment interaction (GGE) biplots analysis. Results: ANOVA devised that the genotypes, environment and genotype × environment interactions were significant for grain yield. The first two principal components, PC1 and PC2 described 73.65 and 26.35 percent variations, respectively, of total variation. According to AMMI I, the genotypes such as Pant M 6, RMG 1092, TMB 134, CoGG 13-19, KM 2349, DGG-8, TRCM 87-6-2-1, KM 2241 and MDGGv-16 were highly stable genotypes. GGE biplot analysis revealed that Pant M 6 and TMB 134 as winning genotypes for Berthin while NMK 15-12 and MDGGV-16 were the best genotypes for Srinagar. The genotypes IPM 14-7 and GAM 5 were found best for Imphal. Overall, high yield and most stable genotype was DGG-8 for northern hilly terrains of India. Interpretation: GGE biplot and AMMI approach could be instrumental in appraising the genotypes performance in multi-environments/locations testing for efficient selection of the stable genotypes.

Separation and identification of differential protein in the insect-resistant and insect-susceptible mungbean / 生物工程学报

In order to find the insect-resistant composition and differentially expressed proteins of mungbean, Jinlv No.7, B20 and Weilv 2117 were used as experimental materials, and the differential proteins and functions of mungbean varieties that are resistant and susceptible to bruchids were compared and analyzed by two dimensional gel electrophoresis (2-DE) and identified by mass spectrometry. Among the samples, 15 protein spots showed a more than 2.5 times reproducible up-regulated, significance 6 of them were successfully identified by the database, and involved three kinds of proteins. They are the alpha and beta subtype 8S globulin, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBis CO) subunits binding protein and the precursor peptide chains for amylase inhibitor and trypsin inhibitor. The protein expressions of B49 (alpha subtype 8S globulin) and B31 (RuBis CO subunits binding protein) of insect-resistant mungbean were 10 000 and 23 times higher than that of insect-susceptible mungbeans. It stunted the growth and even death of the Callosobruchus chinensis L. that alpha and beta subtype 8S globulin and RuBis CO subunits binding protein and precursor peptide chains for amylase inhibitor and trypsin inhibitor of insect-resistant mungbean, the bruchid resistance effect of these three proteins need to further verified in terms of the quantity and the combined effect.

SSR-Marker assisted evaluation of Genetic Diversity in Mungbean ( Vigna radiata (L.) Wilcezk) genotypes

ABSTRACT Mungbean (Vigna radiata (L.) Wilczek) also known as green gram is an important source of protein in the category of food legumes. In the present study, SSR marker is used to analyze the genetic diversity amongst 23 genotypes of mungbean. Out of a total of 10 primers used for SSR analysis revealed generation of 15 alleles. The number of alleles per locus ranged from one (CEDG006, CEDG010, CEDG050, CEDG088, CEDG092 and CEDG232) to three (CEDG 214), with an average of 1.5 allele per primer. The index for expected heterozygosity was 0.29 ranging from 0.15 to 0.49 revealed a deficit in heterozygosity. The size of amplification products varied in case of each primer and the range was found to be 100 bp to 190 bp. 13 out of 15 alleles were found polymorphic. The average PIC value of SSR marker was found to be 0.205. The value of Jaccard's similarity coefficient had ranged from 0.28-1.00 with an average value of 0.64. The dendrogram constructed on SSR molecular marker data through UPGMA method and PCA using average linkage, had enabled grouping of the genotypes into three main clusters. Clustering pattern based on SSR marker data clearly indicated the narrow genetic base of mungbean genotypes that emphasizes the need to explore and exploit more number of germplasm from additional source to study genetic variation in mungbean for genetic improvement. The results indicated the marked usefulness of SSR in the assessment of genetic diversity in mungbean crop.

Potential of Vigna radiata (L.) sprouts in the management of inflammation and arthritis in rats: Possible biochemical alterations.

Vigna radiata (Fabaceae) is an important pulse crop widespread throughout the tropics and warm temperature regions. In this study, we evaluated the in vitro anti-inflammatory and in vivo antiarthritic activity of Vigna radiata sprouts in rats. The in vitro anti-inflammatory activity was determined by membrane stabilization and protein denaturation method. Whereas, the antiarthritic activity of the ethanolic extract of the sprouts was evaluated by complete Freund’s adjuvant model with diclofenac sodium as the standard drug. Body weights, paw volume, biochemical parameters such as lipid peroxidation, total reduced glutathione, myeloperoxidase and lysosomal enzymes like cathepsin-D, N-acetyl β-D-glucosamindase and β-D-glucuronidase were estimated. Treatment with ethanolic extract of V. radiata exhibited significant membrane stabilization activity and protein denaturation activity, and significantly attenuated the biochemical changes induced by administration of complete Freund’s adjuvant. The findings of the present study suggest the possible role of Vigna radiata in the therapeutics of arthritis.

Genotypic Variation for Response to Rhizobial Sp. and Piriformospora Indica for Yield and Yield Components in Mungbean [Vigna Radiata (L.) Wilczek].

Ten mungbean genotypes were evaluated to estimate the genotypic variation for seed yield components and Nitrogen and Phosphorus uptake after inoculating with three microbial treatments (Rhizobium, Piriformospora indica and their combined inoculation). Significant genotypic differences for all characters indicated presence of considerable variability. All the microbial treatments and genotype x microbial interaction differed significantly except for maturity, branches/plant and seeds/pod. The traits affected most by Rhizobium inoculation in majority of the genotypes were plant height, pods/plant and seed yield. Above 50 per cent P. indica infection in roots was observed in eight genotypes, however, its effect was observed only in a few genotypes on plant height, P content in shoot, 100-seed weight and seed yield. The effect of combined inoculation was observed on seed yield only. Effect of all the three inoculants was observed in only MH-810 and MH-721. Maximum response of Rhizobium and dual inoculation was observed in MH-421.

A Through-chain Analysis of Food Safety Hazards and Control Measures Associated with the Production and Supply of Seed Sprouts for Human Consumption.

Background: Seed sprouts contaminated with pathogenic microorganisms, such as Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) present an unacceptable health risk to consumers. An outbreak that occurred in Australia during 2005 and 2006 due to the consumption of alfalfa sprouts contaminated with Salmonella Oranienburg resulted in 141 infected cases, and cost an estimated $1.19 million to the Australian community. In Japan in 1996, consumption of radish sprouts contaminated with STEC O157:H7 affected more than 10,000 individuals. The outbreak of E. coli O104:H4 linked to the consumption of fenugreek sprouts that occurred in Europe in 2011 was an unprecedented foodborne outbreak. More than 4,000 individuals were infected by STEC O104:H4. Among them, 908 developed haemorrhagic uraemic syndrome (HUS), and 50 died of STEC infection. This demonstrates the potential food safety risk arising from seed sprouts and that the consequences can be devastating. Food Standards Australia New Zealand (FSANZ) initiated the development of a primary production and processing standard for seed sprouts in 2009 to enhance the safety of seed sprouts produced and sold in Australia. After extensive consultations with the State and Territory food safety regulators, and a thorough investigation of the Australian industry practices in producing seed sprouts for human consumption, a technical paper was prepared to inform the design of potential risk mitigation measures for a national food safety standard on seed sprout production. This technical paper described the Australian seed sprout industry, depicted the steps involved in the production of seed sprouts for human consumption, and provided an analysis of potential food safety hazards that could occur during seed sprout production and processing. A food safety standard for the production and sale of seed sprouts in Australia was finalised in November 2011. This extended abstract describes the key aspects of the technical paper. Aims: To provide technical and scientific information to support risk management decisions aimed at maximizing the safety of seed sprouts produced for human consumption in Australia. Study Design: A through-chain qualitative food safety risk analysis. Place and Duration of Study: FSANZ, Canberra, Australia, between July 2009 and January 2010. Methodology: This through-chain risk analysis was prepared upon a comprehensive review of literature available at the time on: investigations of foodborne outbreaks associated with consumption of seed sprouts; surveys of microbial contamination of seed sprouts; specific publications on crop production, seed harvest, post-harvest processing and storage of seeds; production of seed sprouts; risk assessments on seed sprouts; and regulatory guidelines published by Australian and international food safety regulatory authorities on seed sprouts. Members of the FSANZ project team conducted field studies of sprout production, lucerne crop production, lucerne seed processing, wholesale and retail sale of seed sprouts. A survey was conducted on the variety, volume and value of sprouts produced, source and quantity of seeds used to produce sprouts for human consumption, trend of consumption of seed sprouts in Australia, as well as the size and the location of sprout producers in Australia. Stakeholders were consulted through a FSANZ standard development committee with participants from State and Territory food safety regulators, peak sprout producer industry bodies, seed producers and seed processors, major food retailers, and consumer representatives. The through-chain analysis of food safety hazards associated with the production and processing of seed sprouts was prepared in line with the principles of hazard analysis critical control points (HACCP). Results: Key pathogens of concern: Among the range of biological, chemical and physical food safety hazards that were likely to be associated with seed sprouts produced for human consumption, pathogenic microorganisms represent the highest risk to consumers. Outbreaks associated with the consumption of seed sprouts contaminated with pathogenic microorganisms were seen to be frequent events in developed economies despite food regulatory interventions. The key pathogenic microorganisms of concern were Salmonella spp. and STEC. Salmonella spp. were found to be the causative pathogen almost five times more frequently than STEC. Main varieties of seed sprouts causing foodborne illness: Among the 41 reported outbreaks that occurred worldwide between 1988 and 2007 involving consumption of seed sprouts contaminated with pathogenic microorganisms, alfalfa sprouts represented 68% of the outbreaks, followed by mingbean sprouts (22%), clover sprouts (5%), radish sprouts (2%) and clover sprouts (2%). Source of pathogenic microorganisms: FSANZ divided the production and supply of seed sprouts for human consumption into eleven consecutive steps, starting with seed production in the field and ending with transportation and distribution of seed sprouts to retail establishments. This was to enable a systematic identification of the food safety hazards, sources of the hazards, specific controls that could be applied to control or eliminate food safety hazards, and the associated requirements of food safety management practices including food safety knowledge and food safety skills. Contamination of seeds by pathogenic microorganisms such as Salmonella spp. and STEC can occur during seed production, seed harvest, seed processing, seed storage and transportation. The origin of these pathogenic microorganisms is animal faeces and manure present in the field where the crop is grown. Soil for growing the seed crop, water used for irrigation, and machinery used for crop management including the harvest of seeds, can be contaminated with pathogenic microorganisms and can transfer the contamination to seeds during crop production and seed harvest. Seed processing as a post-harvest step may also contribute to seed contamination. For example, blending different harvest lots of seeds for seed cleaning can spread what was originally a localised contamination into a larger volume of seeds. Rodent, insect and bird activities in seed processing and seed storage establishments can introduce and spread pathogenic microorganisms to seeds. Provided that seeds delivered to sprout production sites are free of pathogenic microorganisms, activities of rodents, insects, and infected workers in seed receipt, storage, sprout production, sprout storage and transportation at sprouting establishment can lead to contamination of seed sprouts by pathogenic microorganisms. So is the use of contaminated water for sprouting. Much of these are also applicable to retail handling and storage of seed sprouts. Investigations into the source of sprout contamination for outbreaks that occurred between 1988 and 2007 found that in almost every case the pathogenic microorganisms causing the outbreaks were present in the seeds used for sprout production. In approximately 20% of the outbreaks, contamination in sprouting establishments was also identified as a likely source of contamination. Identified risk mitigation measures: Based on an analysis of a wide range of possible recommendations aimed at improving the safety of seed sprouts, the though-chain analysis recommended the following good agricultural practices to be implemented in the primary production phase of seeds: · Environment - soil and environment where seeds are grown for the production of seed sprouts as a human food should be suitable. · Inputs - manure, biosolids and other natural fertilisers should only be used for the growth of seed crops when a high level of pathogen reduction has been achieved; equipment (bins, containers, silos, vehicles) and machinery are maintained and used in a manner that minimises and/or avoids contamination of seeds with pathogenic microorganisms. · Protection - grazing animals and wild animals are prevented from entering the field where seeds are grown; and seed crops are protected from contamination by human, animal, domestic, industry and agricultural wastes. · Segregation - seeds produced for the production of sprouts for human consumption are segregated from seeds produced for the production of animal feed and are clearly labelled. The through-chain analysis also recommended the following components to be included in a Food Safety Program that must be effectively implemented in sprout production establishments: · Environment – the sprouting facility (including the seed storage area) should not allow access of rodents, insects, pests or animals; sprouting facility and equipment are effectively cleaned and sanitised to ensure the environment is suitable for producing ready-to-eat foods. · Input – each seed lot is tested for the presence of microbial pathogens of concern and seeds should not be used unless the testing results are negative; solid medium supporting sprout growth and water for sprouting are treated to eliminate pathogenic microorganisms; seeds are disinfected prior to sprouting to eliminate microbial pathogens. · Separation – seed rinsing and microbiological decontamination, seed germination/sprouting, and storage of seed sprouts are physically separated from each other to prevent cross contamination. · Monitoring – implement appropriate sampling/testing programs to regularly monitor microbial pathogens during and at the end of production of seed sprouts. Implementation of food safety controls on farm presents many challenges. One of the main obstacles is the inability to control environmental factors under conventional farming practices. The environment under which seeds are produced for the production of seed sprouts for human consumption should exclude animal grazing and minimise and avoid pest and wildlife interference. The cost involved in growing seeds under these conditions can be prohibitive unless s

Genetic Divergence Studies in Mungbean (Vigna Radiata L. Wilczek).

Genetic divergence using D2 statistic of forty genotypes of various agro-climatic region for ten quantitative characters revealed existence of considerable genetic diversity in the material. The genotypes were grouped into eleven clusters. Cluster VIII contained the highest number of nine genotypes followed by cluster V with seven genotypes. The pattern of distribution of genotypes from different geographical location into eleven clusters were random, demonstrating that geographical isolation may not be the only factor causing genetic diversity. The highest intra-cluster distance was observed for cluster VI (112.02) and the lowest was observed for cluster II (6.24). While the highest inter-cluster distance was observed between cluster III and X (493.41). Harvest index contributed maximum to diversity. Cluster IX with WGG-66 recorded the highest mean for yield contributing characters viz., plant height, branches/plant, pods/plant and clusters/plant. Therefore it was suggested that more emphasis should be given this genotype as parents for crossing with genotypes of other clusters which may produce novel recombinants with desirable traits.

Genetic Divesity and Molecular Characterization of Mungbean Genotypes (Vigna radiata (L.) Wilczek).

The present investigation was undertaken to examine the genetic divergence in 50 mungbean germplasm lines for 13 characters using Mahalanobis D2 statistics. The genotypes grouped into eight clusters. Cluster VII had maximum intra-cluster distance while inter-cluster distance was highest between clusters V and VII. Cluster means indicated that none of the clusters was superior for all the characters studied. Therefore, hybridization between genotypes belonging to different clusters is suggested for development of superior genotypes. 10 SSR primers were used for molecular study of which only one gave slight difference among 19 mungbean genotypes. The quality and quantity of DNA used for amplification by PCR is the key to reproducible results and success of genotyping. Especially, DNA purity is extremely crucial for obtaining clear and discriminate patterns. DNA extraction from mungbean is difficult due to presence of contaminants such as phenols. Therefore, the present study was under taken to obtain high quality and pure DNA in mungbean. With few modifications four different DNA extraction protocols were tried in the present study to obtain high quality and pure DNA viz., (I) Doyle and Doyle (1987), (ii) Method of Murray and Thompson (1980), (iii) Porebski et al.(1997), and (iv) Lin et al. (2001). Out of the four methods tried for DNA extraction, the method of Lin et al. (2001) was found most efficient, as the DNA obtained through this protocol was relatively pure which gave amplyfying products in the PCR. The genotype used for the standardization was MGG -361. Molecular characterization of 19 randomly chosen mungbean genotypes was attempted with the eight standardized primers. None of the primers showed scorable polymorphism. The primers VR4, VR5 and VR9, exhibited non specific bands, in addition to the monomorphic bands.

NaCl pretreatment alleviates salt stress by enhancement of antioxidant defense system and osmolyte accumulation in mungbean (Vigna radiata L. Wilczek).

Enhancement of salt (NaCl) tolerance by pretreatment with sublethal dose (50 mM) of NaCl was investigated in V. radiata seedlings. NaCl stress caused drastic effects on roots compared to shoots. Accompanying reductions in length, number of root hairs and branches, roots became stout, brittle and brown in color. Salt stress caused gradual reduction in chlorophyll, carotenoid pigment contents and chlorophyll fluorescence intensity also. Superoxide dismutase and catechol peroxidase activities increased under stress in both roots and leaves. But catalase activity showed an increase in roots and decrease in leaves. In these seedlings, the oxidative stress has been observed under salinity stress and the level of proline, H2O2 and malondialdehyde content were increased. But pretreatment with sublethal dose of NaCl was able to overcome the adverse effects of stress imposed by NaCl to variable extents by increasing growth and photosynthetic pigments of the seedlings, modifying the activities of antioxidant enzymes, reducing malondialdehyde and H2O2 content and increasing accumulation of osmolytes like proline. Thus, mungbean plants can acclimate to lethal level of salinity by pretreatment with sublethal level of NaCl, improving their health and production under saline condition.

Role of Arbuscular Mycorrhizal Fungi in Phytoremediation of Soil Rhizosphere Spiked with Poly Aromatic Hydrocarbons

Results from an innovative approach to improve remediation in the rhizosphere by encouraging healthy plant growth and thus enhancing microbial activity are reported. The effect of arbuscular mycorrhizal fungi (Am) on remediation efficacy of wheat, mungbean and eggplant grown in soil spiked with polyaromatic hydrocarbons (PAH) was assessed in a pot experiment. The results of this study showed that Am inoculation enhanced dissipation amount of PAHs in planted soil, plant uptake PAHs, dissipation amount of PAHs in planted versus unplanted spiked soil and loss of PAHs by the plant-promoted biodegradation. A number of parameters were monitored including plant shoot and root dry weight, plant tissue water content, plant chlorophyll, root lipid content, oxido-reductase enzyme activities in plant and soil rhizosphere and total microbial count in the rhizospheric soil. The observed physiological data indicate that plant growth and tolerance increased with Am, but reduced by PAH. This was reflected by levels of mycorrhizal root colonization which were higher for mungbean, moderate for wheat and low for eggplant. Levels of Am colonization increased on mungbean > wheat > eggplant. This is consistent with the efficacy of plant in dissipation of PAHs in spiked soil. Highly significant positive correlations were shown between of arbuscular formation in root segments (A)) and plant water content, root lipids, peroxidase, catalase polyphenol oxidase and total microbial count in soil rhizosphere as well as PAH dissipation in spiked soil. As consequence of the treatment with Am, the plants provide a greater sink for the contaminants since they are better able to survive and grow.

Purification and characterization of Cu-Zn superoxide dismutases from mungbean (Vigna radiata) seedlings.

Mungbean contains three isoenzymes of superoxide dismutase designated isoenzyme I, II and III. The two cytosolic superoxide dismutases (I and II) were purified to homogeneity by ammonium sulphate fractionation, ion exchange chromatography on diethylaminoethyl cellulose, gel filtration and preparative polyacrylamide·gel electrophoresis. The molecular weights of isoenzyme I and isoenzyme II were determined to be 33,000 and 31,600 respectively. The subunit molecular weight was approximately 16,000 indicating that the isoenzymes contained two identical subunits. The ultra-violet absorption spectra revealed a maximum at 258-264 nm for the two isoenzymes. Superoxide dismutase I and II were inhibited to different extents by metal chelators. Isoenzyme I was more sensitive to inhibition by cyanide and azide, while isoenzyme II was more susceptible to inhibition by diethyldithiocarbamate and o-phenanthroline. Both the isoenzymes exhibited similar denaturation profiles with heat, guanidinium chloride and urea. The denaturation with urea and guanidinium chloride was reversible. The two copper-zinc enzymes were more stable towards thermal inactivation compared to manganese and iron superoxide dismutases from other sources. The results indicate that the two isoenzymes differ from each other only with respect to charge and sensitivity towards metal chelators.