Showing papers by "Central Tuber Crops Research Institute published in 2011"

Process optimization for bioethanol production from cassava starch using novel eco-friendly enzymes

Abstract: Although cassava (Manihot esculenta Crantz) is a potential bioethanol crop, high operational costs resulted in a negative energy balance in the earlier processes. The present study aimed at optimizing the bioethanol production from cassava starch using new enzymes like Spezyme® Xtra and Stargen™ 001. The liquefying enzyme Spezyme was optimally active at 90 °C and pH 5.5 on a 10% (w/v) starch slurry at levels of 20.0 mg (280 Amylase Activity Units) for 30 min. Stargen levels of 100 mg (45.6 Granular Starch Hydrolyzing Units) were sufficient to almost completely hydrolyze 10% (w/v) starch at room temperature (30 ± 1 °C). Ethanol yield and fermentation efficiency were very high (533 g/kg and 94.0% respectively) in the Stargen + yeast process with 10% (w/v) starch for 48 h. Raising Spezyme and Stargen levels to 560 AAU and 91.2 GSHU respectively for a two step loading [initial 20% (w/v) followed by 20% starch after Spezyme thinning]/initial higher loading of starch (40% w/v) resulted in poor fermentation efficiency. Upscaling experiments using 1.0 kg starch showed that Stargen to starch ratio of 1:100 (w/w) could yield around 558 g ethanol/kg starch, with a high fermentation efficiency of 98.4%. The study showed that Spezyme level beyond 20.0 mg for a 10% (w/v) starch slurry was not critical for optimizing bioethanol yield from cassava starch, although an initial thinning of starch for 30 min by Spezyme facilitated rapid saccharification–fermentation by Stargen + yeast system. The specific advantage of the new process was that the reaction could be completed within 48.5 h at 30 ± 1 °C.

Retention of carotenoids in orange-fleshed sweet potato during processing.

Abstract: The retention of carotenoids was studied in the storage roots of ten sweet potato clones possessing different intensities of dark orange-flesh colour in four different processing methods—oven drying, boiling, sun drying and frying. The results indicated that the extent of retention varied with the method of processing. The highest retention was observed in oven drying (total carotenoids 90%–91% and β-carotene 89%–96%) followed by boiling (total carotenoids 85%–90% and β-carotene 84%–90%) and frying (total carotenoids 77%–85% and β-carotene 72%–86%). The lowest retention of total carotenoids (63%–73%) and β-carotene (63%–73%) was recorded in the sun drying method.

Antitumour Effects of Isocurcumenol Isolated from Curcuma zedoaria Rhizomes on Human and Murine Cancer Cells

Abstract: Curcuma zedoaria belonging to the family Zingiberaceae has been used in the traditional system of medicine in India and Southwest Asia in treating many human ailments and is found to possess many biological activities. The rationale of the present study was to isolate, identify, and characterize antitumour principles from the rhizomes of Curcuma zedoaria, to assess its cytotoxic effects on human and murine cancer cells, to determine its apoptosis inducing capacity in cancer cells, and to evaluate its tumour reducing properties in in vivo mice models. Isocurcumenol was characterized as the active compound by spectroscopy and was found to inhibit the proliferation of cancer cells without inducing significant toxicity to the normal cells. Fluorescent staining exhibited the morphological features of apoptosis in the compound-treated cancer cells. In vivo tumour reduction studies revealed that a dose of 35.7 mg/kg body weight significantly reduced the ascitic tumour in DLA-challenged mice and increased the lifespan with respect to untreated control mice.

Yersinia enterocolitica: mode of transmission, molecular insights of virulence, and pathogenesis of infection

Abstract: Although Yersinia enterocolitica is usually transmitted through contaminated food and untreated water, occasional transmission such as human-to-human, animal-to-human and blood transfusion associated transmission have also identified in human disease. Of the six Y. enterocolitica biotypes, the virulence of the pathogenic biotypes, namely, 1B and 2–5 is attributed to the presence of a highly conserved 70-kb virulence plasmid, termed pYV/pCD and certain chromosomal genes. Some biotype 1A strains, despite lacking virulence plasmid (pYV) and traditional chromosomal virulence genes, are isolated frequently from humans with gastrointestinal diseases similar to that produced by isolates belonging known pathogenic biotypes. Y. enterocolitica pathogenic biotypes have evolved two major properties: the ability to penetrate the intestinal wall, which is thought to be controlled by plasmid genes, and the production of heat-stable enterotoxin, which is controlled by chromosomal genes.

Rheological, mechanical and moisture sorption characteristics of cassava starch-konjac glucomannan blend films

Abstract: Cassava starch (ST)-konjac glucomannan (KGM) blend films were prepared and their thermal, rheological, mechanical, moisture sorption properties and water vapour transmission rate were determined. Response surface methodology was employed for the preparation of films using different levels of ST, KGM and glycerol. All the filmogenic solutions exhibited shear thinning behaviour. Apparent viscosity and the dynamic rheological properties of filmogenic solutions varied considerably with KGM content. Rheological analysis revealed that the blend films are more appropriate than neat ST film for controlled drug release studies and for food coating. The melting temperature and enthalpy of fusion of the blend films were lower than that of neat ST film. When compared to neat starch film, the blend films showed broader peaks in DSC patterns, which suggests that incorporation of KGM decreased the crystallinity of ST. Mechanical properties, elongation at break and tensile strength of blend films were significantly higher (112.8% and 22.5 MPa, respectively) than those of neat ST film. Due to the more hydrophilic nature of KGM when compared to ST, the WVTR and moisture absorption of blend films were greater than that of neat ST film. Though KGM is more hydrophillic in nature, blend films with higher amount of KGM (0.643g) showed comparably lower values for both WVTR and moisture absorption than other blends. The solubility of the blend films was lower than that of neat starch film which also confirmed the strong intramolecular attraction between ST and KGM.

Effect of processing on the retention of carotenoids in yellow-fleshed cassava (Manihot esculenta Crantz) roots

Abstract: Summary The retention of carotenoids was studied in roots from yellow-fleshed, high carotene cassava clones in four different processing methods. The results indicated that the extent of retention varied with the method of processing. The highest retention was observed in oven drying (total carotenoids 54.70–84.01% and β-carotene 63.90–94.53%) followed by boiling (total carotenoids 47.87–83.79% and β-carotene 51.31–81.04%) and frying (total carotenoids 48.76–79.77% and β-carotene 44.11–83.87%). The lowest retention of total carotenoids (32.86–56.40%) and β-carotene (21.47–56.68%) was recorded in the sun drying method. The variation in the total carotenoids and β-carotene content depends on variety, processing method and initial carotene content of the fresh root.

Biodegradation of cassava starch factory residue using a combination of cellulases, xylanases and hemicellulases.

Abstract: Cassava starch factory residue (CSFR), a low cost solid byproduct of the cassava starch industry, having around 60% unextracted starch and 15% cellulose is a potential candidate for bioethanol production. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of four enzymes such as Multifect ® XL, Optimash™ XL, Optimash™ BG and Accellerase™1000 was studied. Whilst the former three enzymes exerted maximum activity at pH 5.0 and 60 °C, Accellerase had optimum activity at pH 4.5 and 60 °C. The enzyme cocktail, Multifect XL-Optimash XL-Accellerase (5, 15 and 20 g enzyme protein kg −1 CSFR respectively) was more effective than sequential process with the same enzyme loading. Hydrothermal treatment (HT) of CSFR for 30 min at 100 °C enhanced the susceptibility to enzymatic cleavage as compared to HT for 45 and 60 min as well as autoclaving or microwave exposure. Optimash BG was the most effective on HT CSFR and approximately 704.8 g glucose was released kg −1 CSFR. The high yield of glucose indicates the potential use of hydrothermally treated CSFR as a cheap substrate for ethanol production.

Whey Protein Concentrate Fortified Baked Goods from Cassava-Based Composite Flours: Nutritional and Functional Properties

Abstract: Composite flours are extensively used in the bakery industry to develop designer food products, having specific nutritional or functional properties. Though rich in carbohydrate, cassava flour has not been properly exploited for making bakery products, mainly because of its low protein content contributing to poor dough characteristics. Induced malting using amylolytic enzymes and pregelatinization through hydrothermal cooking were tried to modify the textural and functional attributes of cassava flour, which was then blended with various cereal and legume additives as well as rice bran and used for making two baked products such as muffins and biscuits. Whey protein concentrate (WPC) was added to fortify protein in all the formulations. Pseudo-malted cassava flour-based muffins and biscuits had lower starch content (36–44% and 36.5–41.2%, respectively) than similar products from unmalted cassava flour (39–46% and 43.75%, respectively). The crude protein content of the muffins and biscuits from WPC fortified composite mixes ranged from 7.96% to 14.36% and 9.63% to 11.00%, respectively, which was significantly higher than the native cassava flour (1.30%). Besides, the total dietary fiber could be enhanced to the extent of 1.54–3.10% in muffins and 1.70–2.61% in biscuits, through fortification with cereal and/or legume flours or bran sources, which is also considerable when compared to only 0.435% in native cassava flour. In vitro starch digestibility was the lowest for cassava (unmalted)-/rice bran-based muffins (25.02 units) and cassava (unmalted)-/finger millet flour-based biscuits (36.08 units), indicating the potential of these combinations for making therapeutic baked products for obese and diabetic people. Spread ratio and spread factor were the least (9.27 and 60.99, respectively) for the biscuits made with unmalted cassava/finger millet mixes, while use of Termamyl pseudo-malted cassava/finger millet raised the spread ratio to 11.11 and spread factor to 73.09.

Hydrothermal modifications of tropical tuber starches – Effect of ANN on the physicochemical, rheological and gelatinization characteristics

Abstract: Cassava, sweet potato and arrowroot starches were hydrothermally modified by ANN under different conditions of temperature, moisture and time duration of treatment and the properties are compared. ANN brought about changes in swelling volume, solubility, gelatinization and rheological properties. The three starches behaved differently after the treatment. All the three tuber starches showed decrease in swelling volume after ANN treatment. The solubility decreased for cassava starch, whereas it slightly increased for majority of annealed sweet potato starches and significantly increased for arrowroot starch. For cassava starch, there was a decrease in peak viscosity, but for the other two starches, it increased after ANN. Differential scanning calorimetric studies showed that ANN resulted in a narrowing of DSC patterns for all the starches. The effect of ANN on the dynamic rheological properties was found to depend up on the source of starch. The modification resulted in increased gel hardness, gumminess, adhesiveness and decreased springiness for the starch gels. Tuber starches became less susceptible to enzyme action after ANN.

Effect of Lime, Inorganic, and Organic Sources on Soil Fertility, Yield, Quality, and Nutrient Uptake of Sweet Potato in Alfisols

Abstract: Field experiments were conducted in Alfisols to study the effect of integrated use of lime, inorganic, and organic manures on soil health and sweet potato performance. Integrated use of nitrogen, phosphorus, and potassium and farmyard manure recorded a significantly higher tuber yield (18.7 Mg ha−1) followed by lime + farmyard manure + neem cake + green manure (17.7 Mg ha−1). Incorporation of organics and 100% nitrogen, phosphorus, and potassium showed a yield response of 23%, 2%, and 10% in respect of farmyard manure, neem cake, and green manure over nitrogen, phosphorus, and potassium. A yield response of 12%, 10%, and 13% was observed due to incorporation of lime along with ½ nitrogen, phosphorus, and potassium and organics (farmyard manure, neem cake, and green manure) over that of unlimed plots. Conjunctive use of organic manures along with balanced fertilizers and lime not only produces higher crop yields but also enhanced the efficiency of added nutrients and sustains the soil fertility.

Paddy straw as a substrate for the cultivation of Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum (W.Curt.:Fr.) P. Karst. in India.

Abstract: Lingzhi or Reishi medicinal mushroom, Ganoderma lucidum, is generally cultivated on hardwood logs or sawdust/woodchips based formulations. More than 100 million tonnes of paddy straw is being produced in India per year, and almost 50% of the straw is potentially available for growing mushrooms. In the present study an attempt was made to use paddy straw as a substrate to cultivate G. lucidim. Different proportions of paddy straw were mixed with 0, 22.5%, 45%, and 67.5% sawdust and 10% rice bran. Spawn run period, fruiting initiation period, yield, moisture content, dry recovery, and fruiting body characteristics were recorded and compared. Fructification was observed with all the substrate formulations and they did not show any significant difference in yield. The highest biological efficiency (BE) (29.9%) was observed with the combination sawdust:paddy straw:rice bran 22.5:67.5:10, followed by saw dust:paddy straw:rice bran 45:45:10 with BE 27.3%. The current study demonstrated for the first time that the cultivation of G. lucidum is possible with paddy straw as the base substrate and indicated the enormous potential of paddy straw for the cultivation of G. lucidum.

Purification, characterization and application of thermostable exo‐polygalacturonase from streptomyces erumpens mtcc 7317

Abstract: Exo-polygalacturonase (exo-PG) has a wide range of applications in food processing, i.e., juice extraction, clarification of wine, bakery and distillery industries. Culture parameters for optimum production of extracellular exo-PG by thermostable Streptomyces erumpens Microbial Type Culture Collections 7317 were found to be incubation period (36 h), pH (7.0) and temperature (50C). Enzyme production was higher in beef extract (1%) as nitrogen source as compared with others (casein, peptone, yeast extract, ammonium nitrate, etc.). The purified enzyme (by ammonium sulfate precipitation) had a molecular mass of 63.0 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Crude PG from S. erumpens was compared with marketed pectinase (Pectinex, Novozyme, Bagsvaerd, Denmark) in extraction of juice from vegetables (beet roots, carrot and sweet potato) and fruits (guava and pineapple). A 15–20% increase in juice yield was observed from vegetables and fruits with application of S. erumpens PG over Pectinex. PRACTICAL APPLICATIONS The results showed that a moderately thermostable exo-polygalacturonase (exo-PG) was produced by the actinomycetes strain Streptomyces erumpens MTCC 7317 in submerged fermentation. This enzyme can be used in extraction, clarification and depectinization of vegetables and fruit juices whose pHs are around 7.0. Furthermore, the efficiency of the enzyme has been compared with that of standard pectinase (Pectinex, Novozyme, Bagsvaerd, Denmark) for extraction of juice from vegetables (i.e., beet root [Beta vulgaris L.], carrot [Daucus carota L.] and sweet potato [Ipomoea batatus L.]) and fruits (i.e., guava [Psidium guava L.] and pineapple [Ananas comosus L.]). There was 15–20% increase in juice yield from these vegetables and fruits with the application of crude S. erumpens exo-PG over Pectinex.

Characterisation of Phytophthora colocasiae isolates associated with leaf blight of taro in India

Abstract: Leaf blight and corm rot caused by Phytophthora colocasiae are the most devastating diseases of taro. Fourteen P. colocasiae isolates collected from different states of India were characterised for mating type, metalaxyl fungicide sensitivity and aggressiveness on taro. These organisms were identified as P. colocasiae based on morphological characteristics, internal transcribed spacer (ITS) sequence homology and pathogenicity to taro plants. Ribosomal DNA (rDNA) ITS regions of P. colocasiae isolates were examined, and compared with additional Phytophthora species. All isolates of P. colocasiae fell within a single cluster in phylogenetic trees, regardless of their geographic origins. These isolates were more closely related to Phytophthora capsici. All isolates except the isolate collected from Sikkim state of India (98–111) were sensitive to metalaxyl at 100 ppm and it was also scored for causing higher average foliar disease and tuber rot ratings. Isolates tested exhibited four growth patterns in cultur...

Survey of Cassava Mosaic Disease in Kerala

Abstract: A survey was conducted on the incidence of cassava mosaic disease (CMD) in Kerala. Cassava mosaic disease occurred throughout the state at low to high incidences (44.5-96.75%) in the 35 regions surveyed. The disease incidence was higher in Thiruvananthapuram and Kollam districts and lower incidence was noticed in Wayanad district. Maximum white fly population was also observed in Thiruvananthapuram district of Kerala followed by Kollam. Survey results alsoindicate that Sri Lankan Cassava Mosaic Virus (SLCMV) is wide spread in Kerala.

Induced Systemic Resistance in Biocontrol of Plant Diseases

Abstract: Induction of resistance to pathogens by some strains of plant growth-promoting rhizobacteria (PGPR) and other microorganisms is termed induced systemic resistance (ISR). In contrast to systemic acquired resistance, ISR develops as a result of the colonization of plant roots by PGPR and other plant-beneficial microorganisms. ISR is mediated predominantly by a jasmonate- or ethylene-sensitive pathway. Some strains of Pseudomonas, Bacillus, Serratia, Trichoderma, etc., elicit ISR in plants against different pathogens. PGPR may activate inducible defense mechanisms in the plant in a way similar to pathogenic microorganisms. The modes of action in ISR may involve, inter alia, a variety of determinants. Though ISR offers a broad-spectrum disease management strategy, much remains to be discovered about how the determinants are perceived and ultimately give rise to ISR. In addition to unraveling the molecular regulation in ISR, deciphering microbial signals that are most effective in eliciting resistance is equally challenging for future research endeavors.

Correlated mutations via regularized multinomial regression

Abstract: Background In addition to sequence conservation, protein multiple sequence alignments contain evolutionary signal in the form of correlated variation among amino acid positions. This signal indicates positions in the sequence that influence each other, and can be applied for the prediction of intra- or intermolecular contacts. Although various approaches exist for the detection of such correlated mutations, in general these methods utilize only pairwise correlations. Hence, they tend to conflate direct and indirect dependencies.

Detection and Identification of Dasheen mosaic virus Infecting Colocasia esculenta in India.

Abstract: Reverse transcription polymerase chain reaction of the infected leaf samples of Colocasia esculenta plants showing severe whitish feathery symptoms were carried out using Potyvirus group specific primers, resulting in an amplicon of 327 bp, encoding the core region of the coat protein gene. Sequencing and BLAST analysis showed that the virus is distinct, closely related to Dasheen mosaic virus (DsMV). Sequence analysis revealed 86 and 96% identity at the nucleotide and amino acid level respectively with the DsMV isolate SY1(accession Number AJ628756). This is the first molecular level characterisation of the DsMV infecting C. esculenta in India.

Optimization of synthesis and characterization of cassava starch-graft-poly(acrylonitrile) using response surface methodology

Abstract: Graft copolymerization of poly(acrylonitrile) onto cassava starch was carried out with potassium persulphate (PPS) as the free radical initiator using a response surface Box–Behnken design. Different levels of monomer concentration, initiator concentration, and temperature were used, and regression models were generated in terms of these factors, which can be used to predict the grafting level and efficiency at a given level of the factors. The grafted starches were characterized by FTIR, XRD, and SEM analyses and determination of %grafting (%G), N-content, thermal properties, water and saline solution retention, and rheological properties. Under the conditions used, %G was found to depend only on the temperature used for the reaction. The maximum %G of 120.1 was obtained for the sample synthesized under the following conditions: weight of AN = 0.753 mol/10 g starch, weight of PPS = 0.284 g and temperature = 55°C, and the grafting efficiency was 30.03%. The absorption bands at 2243 cm−1 for the nitrile group (CN) in the FTIR spectra of the products confirmed the grafting reaction. There was a decrease in crystallinity and disappearance of the granular structure after grafting of the starch. The melting temperatures of the graft copolymers determined by differential scanning calorimetry analysis were higher than that of the native starch. The grafted starches exhibited very high thermal stability as observed from the thermogravimetric analysis. The superabsorbent polymer prepared from the grafted starch by alkali saponification exhibited a maximum water absorbency of 636 g/g. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Design and evaluation of sustained release matrix tablets of levofloxacin for effective treatment of microbial infections

Abstract: The objective of present work was to formulate and evaluate sustained release matrix tablets of levofloxacin for treating microbial infections effectively. Levofloxacin is the active component of the racemate ofloxacin, and used for treating a variety of clinical conditions such as lower respiratory tract infections, acute sinusitis, uncomplicated skin and soft-tissue infections and complicated urinary tract infections. Different formulations were prepared by wet granulation method using various release rate controlling hydrophilic polymers. The formulations were evaluated for hardness, weight variation, friability and drug content uniformity. The in vitro release of drug from the formulations was studied in pH 1.2 acidic buffer and pH 6.8 phosphate buffer, and it was found that the prepared tablets were able to sustain the release of the drug. The release of levofloxacin from the tablets was diffusion controlled and the release mechanism was non-Fickian. For conclusion, the developed formulations may reduce the dosing intervals, reduce the dose related side effects and increase the drug’s efficacy for treating infections. Keywords: Matrix tablets, levofloxacin, HPMC, guar gum, xantham gum, locust bean gum, Amorphophallus starch.

Ethanol production from mahula (Madhuca latifolia L.) flowers using free and immobilized (in Luffa cylindrical L. sponge discs) cells of Zymomonas mobilis MTCC 92

Abstract: A novel immobilization method involving Zymomonas mobilis immobilized in a luffa (Luffa cylindrica L.) matrix for ethanol production from mahula (Madhuca latifolia L.) flowers was investigated. The dried spongy fruits of luffa, a cucurbitaceous crop available in abundance in tropical and sub-tropical countries, have been found to be a promising material for immobilizing microbial cells. In our study, the cells not only survived, but they were also active physiologically for four growth cycles, yielding ethanol at 251.1 ± 0.012, 247.9 ± 0.08, 243.4 ± 0.042 and 240.71 ± 0.033 g/kg flowers in the first, second, third, and fourth cycles, respectively, after 96 h fermentation. Ethanol production by the immobilized cells was 9.2% higher than that by free cells. The ethanol yield (Yp/s), volumetric substrate uptake (Qs), and final sugar to ethanol conversion rate (%) obtained with luffa-immobilized cells of Z. mobilis were 0.439 ± 0.004 g/g, 0.994 ± 0.009 g/l/h, and 87.8%, respectively, which were 7.06, 2.62, and 6.92% higher than that of free cells.

Bioaugmentation and Biovalourization of Agro-Food and Beverage Industry Effluents

Abstract: Food and beverage industry effluents form a major chunk of agro-industrial wastes throughout the world. Food industry effluents mainly come from starchy foods, olive oil mill, palm oil mill, sugar refining and fermentation industries. It is imperative to review the present status of food processing waste utilization for their safe disposal. Microbes are well-suited natural agents for recycling of organic wastes including effluents. Many microorganisms, well known for their hydrolytic enzyme production potential, may be employed for biodegradation of organic matter to reduce the biological oxygen demand and chemical oxygen demand of these effluents. This review discusses the microbial remediation options to biovalourize wastewaters by production of value-added products from agro-food and beverage industry effluents as well as their safe disposal.

Effect of Tuber Crop Wastes/Byproducts on Nutritional and Microbial Composition of Vermicomposts and Duration of the Vermicomposting Process

Abstract: A pot culture experiment on vermicomposting of cassava and sweet potato wastes/byproducts was conducted for March–May (season I) and June–August (season II) during 2010 at the Regional Centre of Central Tuber Crops Research Institute, Bhubaneswar, Orissa. The study revealed that the vermicompost prepared from biomass and byproducts of tuber crops had fairly higher levels of nitrogen (1.12–2.23%), phosphorus (0.26–0.88%), and potassium (0.33–1.29%) compared to initial status. The vermicompost prepared from sweet potato dry leaves had the highest nitrogen (2.23% and 2.03%), phosphorus (0.88% and 0.69%), and potassium (1.29% and 0.84%) content during both the years of study. Cassava thippi (tuber residue) required 40–43 days for the complete conversion into vermicompost, whereas all other biomass and byproducts needed more time (43–65 days). The rate of increase of earthworm weight and population was higher in vermicompost made from cassava and sweet potato thippi. Microbial counts indicated that populations of bacteria and fungi were higher in season I, whereas actinomycetes were higher in season II. The study indicated that all the biomass and byproducts of tuber crops can be effectively converted into high-value vermicompost.

Molecular detection and identification of Dasheen mosaic virus infecting Amorphophallus paeoniifolius

Abstract: Occurrence of various types of viral symptoms viz. mosaic, mottling, puckering, stunting and filiformy/shoestring was noticed on Elephant foot yam in India. Immunosorbent electron microscopy of infected leaf samples with Potyvirus group–specific antiserum revealed the association of flexuous Potyvirus particles. Infected leaf samples were collected from different locations in Kerala, Orissa and Andhra Pradesh; and total RNA was extracted from infected leaves. One-step reverse transcription polymerase chain reaction assay was carried out using Potyvirus group–specific primers and an amplified product of 327 and 719 bp were obtained. Sequence analysis of nucleic acid and deduced amino acid sequences with the already available Potyvirus sequences in Genbank showed 91% and 97% similarity with Dasheen mosaic virus (DsMV) isolate DeSLK2 (accession Number AJ305434) at nucleic acid and amino acid level respectively. Comparison of 3′UTR region using universal primers MJ1 and M4T also confirmed that the virus under...

Starch content and cassava mosaic disease genetic diversity with relation to yield in south Indian cassava (Manihot esculenta Crantz) germplasm

Abstract: Cassava, family Euphorbiaceae, is the fifth most important staple food crop. The study of variability and diversity present in diverse cassava accessions maintained at the field genebank of TCRS, TNAU is essential to design the breeding program of cassava in TNAU. Hence, a study was carried out to assess the genetic diversity based on morphological traits and Simple Sequence Repeat (SSR) markers, identifying the SSR markers linked to a cassava mosaic disease-resistant QTL region. Genetic diversity among cassava germplasm accessions was estimated using 28 morphological traits and three SSR markers. The polymorphic information content (PIC) result gives high information for all the SSR markers. Morphological traits revealed 10 clusters and the SSR markers revealed 13 clusters at a similarity coefficient of 2.514 and 0.75, respectively. The SSR marker diversity revealed that the most promising clusters (II and XII) possessing accessions with yield attributing traits and cluster IX were grouped together due to low yield and CMD susceptibility. Morphological descriptors revealed variance for yield contributing traits. The first three principle components accounted for 10.8, 9.1, and 8.4%, respectively. Correlation studies showed significant correlation among yield and yield-attributing traits, which in turn influences yield. The morphological traits diversity reveals that cluster VI was the most promising cluster in which genotypes ME209 and ME460 possess higher yield and starch content with cassava mosaic disease (CMD) resistance. Most of the accessions grouped under cluster X belong to selection from International Centre for Tropical Agriculture (CIAT) collections and the cultivars under clusters I and II were true cassava seed (TCS) selections of India. The CMD-linked SSR marker which is reported in the previous studies have generated eight alleles and each were regressed with CMD resistance and resulted in non-significant linkage to CMD resistance.

Characterisation of the coat protein gene of dasheen mosaic virus infecting elephant foot yam

Abstract: A strain of Dasheen mosaic virus (DsMV) from Amorphophallus paeoniifolius (Elephant foot yam) plants showing leaf mosaic, puckering and shoestringing was characterized by RT-PCR and amplification of a 1.2 kbp fragment encoding the coat protein (CP) gene and the 3’ untranslated region (UTR). BLAST analysis of the cloned DNA amplicon of DsMV-Amp1 revealed at least 80% nucleotide sequence identity with other DsMV isolates from different hosts and geographic origins. The CP gene and the 3’ UTR of DsMV-Amp1 consisted of 942 and 260 nucleotides, respectively. The highest nucleotide sequence identity (89%) was with DsMV-ch from Caladium from the USA, and the deduced CP amino acid sequence had 92-98% identity with other DsMV isolates. Nucleotide sequence identity of 82-85% was also found with Vanilla mosaic virus (VMoV), whereas the identity with Bean common mosaic virus (BCMV), Hardenbergia mosaic virus (HaMV) and Watermelon mosaic virus (WMV) ranged from 74 to 79%. Several potential threonine- and asparagine-rich N-glycosylation motifs and a DVG motif potentially involved in aphid transmission were found in the CP of DsMVAmp1. This is the first characterization of DsMV from A. paeoniifolius plants in India.

Microbial Control of Postharvest Diseases of Fruits, Vegetables, Roots, and Tubers

Abstract: Postharvest diseases cause considerable losses to harvested fruits, vegetables, roots, and tubers during transportation from farmers’ field to market and in storage. Synthetic fungicides are the primary means to control postharvest diseases. However, microbial control has emerged as one of the most promising alternatives to chemical fungicides. Several microbial agents have been widely investigated for use on different postharvest pathogens. The efficacy of the microbial antagonist(s) can be enhanced if they are used with low doses of fungicides, salt additives, and plant products. At the international level, different microbial antagonists such as Candida sake, Candida oleophila, Cryptococcus laurentii, and Debaryomyces hansenii are being used. Biocontrol products such as Aspire, BioSave, and Shemer have also been developed and registered. Although the results of this technology are encouraging, the formulation and application methods are key issues for the efficacy and successful outcome of the commercial product.

Management of mealybug (Rhizoecus amorphophalli) in elephant foot yam (Amorphophallus paeoniifolius).

Abstract: Amorphophallus paeoniifolius, popularly known as elephant foot yam, is an important tropical tuber crop in India. Its modified stem (corm) is consumed as a vegetable after boiling, baking or frying. Mealybug (Rhizoecus amorphophalli), a soft-bodied insect, infests the corms both in storage and in the field. Though pesticides are effective in controlling mealybugs, they can be hazardous to human health and the environment. Two experiments, one in storage followed by one in the field, were conducted during 2009 and 2010 at the Regional Centre of Central Tuber Crops Research Institute, Dumuduma, Bhubaneswar, India, to determine the effect of six low cost and environmentally safe management practices on mealybug. In the absence of mealybug control measures, mealybug numbers increased by 4–5 times during the storage period. The pest affected the quality of the corms and reduced subsequent field establishment and crop growth. Salt (NaCl) solution (1000 ppm), cow urine, cow dung slurry (2 kg of cow dung in 1 litre of water) and clay slurry (1 kg of clay in 1 litre of water) treatments were effective in reducing mealybug numbers and the associated corm damage. However, availability of cow urine, cow dung and clay slurry limit their usage. Common salt is cheap, widely available and easy to use in treating the corms prior to storage. Relative to untreated corms, those treated with salt solution recorded greater emergence when field planted as well as producing plants with more vigorous growth.

Bemisia tabaci (Genn.): Biotypes and Cassava Mosaic Virus in India

Abstract: Biology of Bemisia tabaci on five different host plants viz., cassava, sweet potato, cotton, egg plant and tobacco showed that developmental duration was maximum on cassava and fecundity was maximum on tobacco. Population of cassava whitefly (CWF) and sweet potato whitefly (SPWF) separately maintained on the respective host plants were used in two sets of experiments viz., choice and no-choice studies on cassava, sweet potato, egg plant, cotton, tobacco and tomato. Oviposition was recorded on all host plants, but no CWF nymphs emerged beyond the first instars on sweet potato, while there was no pupal formation or adult development of SPWF on cassava. In choice tests, CWF reproduced on cassava, egg plant, tomato and tobacco, but not on cotton and sweet potato. Conversely, SPWF reproduced on sweet potato, cotton, egg plant, tomato and tobacco, but not on cassava, indicating two different biotypes. In isozymes studies five non-shared alleles to CWF and six to SPWF were observed, ascertaining the biotypes. The analysis of amplification products obtained using the single primers revealed that the CWF and SPWF do not share any similarity among them, confirming the biotypes. Secondary endosymbionts were not associated with the two biotypes.