Showing papers by "Central Tuber Crops Research Institute published in 2015"

Cassava Virus Diseases: Biology, Epidemiology, and Management

Abstract: Cassava (Manihot esculenta Crantz.) is the most important vegetatively propagated food staple in Africa and a prominent industrial crop in Latin America and Asia. Its vegetative propagation through stem cuttings has many advantages, but deleteriously it means that pathogens are passed from one generation to the next and can easily accumulate, threatening cassava production. Cassava-growing continents are characterized by specific suites of viruses that affect cassava and pose particular threats. Of major concern, causing large and increasing economic impact in Africa and Asia are the cassava mosaic geminiviruses that cause cassava mosaic disease in Africa and Asia and cassava brown streak viruses causing cassava brown streak disease in Africa. Latin America, the center of origin and domestication of the crop, hosts a diverse set of virus species, of which the most economically important give rise to cassava frog skin disease syndrome. Here, we review current knowledge on the biology, epidemiology, and control of the most economically important groups of viruses in relation to both farming and cultural practices. Components of virus control strategies examined include: diagnostics and surveillance, prevention and control of infection using phytosanitation, and control of disease through the breeding and promotion of varieties that inhibit virus replication and/or movement. We highlight areas that need further research attention and conclude by examining the likely future global outlook for virus disease management in cassava.

Plantain peel - a potential source of antioxidant dietary fibre for developing functional cookies

Abstract: Plantain cultivar Nendran is popular as a staple food in many parts of India and deep fried chips made from raw matured Nendran are one of the popular snack items in India. This study aims to utilize peel from Nendran variety- the main byproduct of banana chips industry- to develop high fibre cookies with enhanced bioactive content. Proximate analysis indicated that peels are rich in total dietary fibre (64.33 g/100 g), vitamins (Folic acid- 33.12 mg/100 g) and minerals (Potassium- 35.61 mg/100 g). Nendran Peel Flour (NPF) was extracted with hexane, ethyl acetate and methanol. Phenolic and flavonoid content was high for ethyl acetate extract (15.21 and 9.39 mg QE/g dry weight). Methanol extract was more potent in reducing Copper ion (2.36 μM TR/g dry weight) and scavenging NO (IC50-381.71 μg/mL). Ethyl acetate extract was capable of scavenging DPPH and hydroxyl radical. HPLC profiling showed presence of gallic acid, protocatechuic acid, rutin hydrate and quercetin in ethyl acetate extract and gallic acid, chlorogenic acid and vanillic acid in methanol extract. Cookies prepared with NPF possess higher total dietary fibre content. There was a decrease in spread ratio, breaking strength and browning index of cookies as the percentage of NPF increased. NPF incorporation gradually increased the phenolic content from 4.36 to 5.28 mg GAE, compared to control cookie (3.21 mg GAE). DPPH scavenging activity also increased with increase in NPF. Hence NPF is a very good source of antioxidant dietary fibre and acceptable cookies can be produced by replacing wheat flour with 10 % NPF.

Unveiling the compatibility of eugenol with formulation excipients by systematic drug-excipient compatibility studies

Abstract: The drug-excipient compatibility studies were carried out with the possible excipients viz. Tween 80, Carbopol 940, chitosan, sodium alginate, and polycaprolactone (PCL) for their possible use in the formulation of eugenol loaded nanoemulsion gels and nanoparticles. The eugenol-excipient compatibility studies were carried out by visual observations, differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and high-performance thin-layer chromatography (HPTLC). No notable change was observed in the samples on visual observation. From the results of the DSC studies, to a much extent, it was assumed that eugenol was not subjected to any interaction with the selected excipients for the proposed nanoemulsion gel and nanoparticles. But in some cases viz. polycaprolactone and Carbopol, though not to a significant level, slight deviation of the nature and position of the endothermic peaks of eugenol were observed. The results of the IR spectroscopy confirmed the compatibility of eugenol with Tween 80, Carbopol 940, chitosan, sodium alginate, and polycaprolactone. The retention factor of the HPTLC densitogram peaks for all the physical mixtures was well within the retention factor (Rf) value range observed for pure eugenol. The study results confirmed that eugenol is compatible with the selected excipients for the development of nanoemulsion gels and nanoparticles.

Enhancing the Enzymatic Saccharification of Agricultural and Processing Residues of Cassava through Pretreatment Techniques

Abstract: The aerial part of the cassava plant comprising stems, leaves and cassava peels are waste biomasses generated during the cultivation and processing of cassava. The potential of these biomasses as alternative substrates for the production of bioethanol was investigated. The efficacy of three types of pretreatments such as (i) hydrothermal treatment, (ii) microwave exposure of acid slurry and (iii) dilute acid treatment (steam as well as under pressure) in enhancing the enzymatic degradability of agricultural residues of cassava was investigated. Whilst cassava stems and peels had 15.00 and 29.84 % starch along with 22.8 and 14 % cellulose respectively, dry leaves had only 2.43 % starch and 17.3 % cellulose. Hemicellulose ranged from 23 to 29 % in these biomasses. The pretreated biomasses were compared with the native samples for the fermentable sugar yield during enzyme saccharification by the cellulolytic enzyme complex, Accellerase™ 1000. Among the pretreatments, hydrothermal treatment (HT) of moist powders for 30 min was the most effective in giving the highest yield of reducing sugars, followed by microwave assisted dilute acid treatment for 20 min. Extending the exposure time for HT to 45 and 60 min reduced the sugar yield. Leaf was the most recalcitrant among the three biomasses. Ultrastructural studies using Scanning electron microscopy also supported the saccharification data. Very high extent of release of sugars during saccharification was noticed from cassava peels which also had Ca. 29.84 % starch. Optimal level of Accellerase required for saccharification was 500 mg enzyme protein. It was concluded from the study that hydrothermal treatment of the powdered biomasses for 30 min was the most appropriate technique to enhance the biodegradation by cellulolytic enzymes.

Anthocyanin-Rich Sweet Potato (Ipomoea batatas L.) Beer: Technology, Biochemical and Sensory Evaluation

Abstract: The global consumption of beer is increasing and consumers are interested in varieties rather than the only traditional beer prepared from malted barley; hence, it is necessary to search for unique potential substrates for beer production. The current study focuses on the preparation technology and the biochemical and sensory characteristics of beer samples by using purple sweet potato (PSP) (Ipomoea batatas L.) flakes as ingredient. Anthocyanin-rich beer was developed by fermenting a combination of PSP flakes and grist (crushed malt) prepared from barley through Saccharomyces cerevisiae without altering the originality of beer preparation. Among the beer samples (prepared from 0, 30, 50 and 100% PSP flakes as adjunct), the beer prepared from 30% PSP flakes + 70% grist was the best as recommended by the sensory panelists, followed by the beer prepared from 50% PSP flakes + 50% grist. The beer prepared with 30% PSP flakes had the following compositions: total soluble solids, 3.57 °Brix; starch, 0.77 g/100 mL; total sugar, 6.93 g/100 mL; specific gravity, 1.02; pH, 3.05; titratable acidity, 0.76 g tartaric acid/100 mL; lactic acid, 0.10 mg/100 mL; phenol, 0.21 mg/mL; anthocyanin, 5.10 mg/100 mL; ethanol, 3.77% (v/v) and DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, 6.31% at a dose of 250 μg/mL. Strong loading of anthocyanin pigment (+ve), phenol (+ve) and the DPPH scavenging activity (+ve) on PC1 signifies the health attributes of the beverages. Practical Applications Anthocyanin-rich sweet potato beer is a novel product that beholds antioxidative properties, unique purple color and low alcohol content (3.77%). The product is well accepted by the sensory panelists. The technology will provide pathway to use sweet potato as ingredient for beer making in large scale. The cheaper cost of sweet potatoes and the simpler technology will attract the brewers to adopt the technology, which can help in the socioeconomic upliftment of several tribal communities of Asia and Africa as they depend on sweet potato cultivation for their livelihood.

The growth of tomato seedlings inoculated with co-cultivated Piriformospora indica and Bacillus pumilus.

Abstract: A novel co-culture method using the beneficial root endophytic fungus Piriformospora indica and a plant-growth promoting rhizobacterial strain of Bacillus pumilus to promote the growth of tomato seedlings in plug trays, is described. Coconut water, a waste product from the coconut industry, was used as medium for co-cultivation of the two biological agents. During the co-culture with the fungus, the bacterial strain showed a similar growth rate to that in monoculture in fresh autoclaved coconut water. In contrast, co-culture in potato dextrose broth (PDB), a medium routinely used for cultivation of the endophytic fungus, did not support bacterial growth. Inoculation with the co-culture or a mixture of P. indica and B. pumilus promoted tomato seedling growth significantly when compared with individual application of the two biological agents. No difference was observed with respect to the degree of root colonization in tomato seedlings whether it was done with a monoculture or a co-culture with rhizobacterium. The co-culture system developed reduces the cost of inoculum production as it uses coconut water, a cheap and locally available waste product and a single fermentation vessel. Further research is required to know the endophytic nature of the rhizobacterial strain and its possible role in helping the fungus in root colonization.

Cassava starch‐poly(vinyl alcohol) nanocomposites for the controlled delivery of curcumin in cancer prevention and treatment

Abstract: Curcumin, a natural yellow pigment with a wide spectrum of bioactivities, was incorporated in nanocomposite films of cassava starch with poly(vinyl alcohol) (PVA) for achieving sustained release properties which improves its potential for use in cancer treatment The ultra structure of the films was studied by scanning electron microscopy (SEM) and the formation of nanoparticles was confirmed by transmission electron microscopic (TEM) analysis The curcumin incorporation in the films was confirmed by Fourier transform infra red spectroscopy (FTIR) The swelling capacity and erosion of the films were also recorded It was observed that pH of the medium and storage conditions greatly affected the release of curcumin from the polymer matrices The release behaviour of curcumin from starch-PVA matrices was studied and the kinetics behind the curcumin release was fitted to Higuchi model The mechanism obtained from Korsemeyer-Peppas equation was a combination of diffusion and erosion controlled Cytotoxicity study of the incorporated curcumin was carried out with normal as well as cancer cells and the results showed that it was non-toxic to normal cells and it also showed anticancer potential The cell viability (%) in the case of cancer cells was lower for nanocomposite incorporated curcumin than pure curcumin which indicates higher anti cancer potential of the former The size of curcumin was reduced in the nanocomposites as evidenced from TEM and SEM analysis results, which might have resulted in its greater cell availability and resultant higher anticancer activity

Detection of mosaic virus disease in cassava plants by sunlight-induced fluorescence imaging: a pilot study for proximal sensing

Abstract: Cassava mosaic disease CMD is a prominent virus infection that causes considerable crop damage and yield reduction. Early detection of crop damage by remote sensing could be a useful tool for initiating remedial measures to reduce further crop damage. This article presents a non-destructive method for detection and classification of CMD infection, based on the red:far-red chlorophyll chl fluorescence image ratio. This pilot study was carried out in 14 varieties of potted cassava plants Manihotesculenta Crantz with a multispectral imaging system MSIS consisting of an electron multiplying charge coupled device EMCCD camera. Sunlight-induced chl fluorescence SICF images of plant leaves were recorded using the MSIS at the Fraunhofer lines of O2-B at 687 nm and O2-A at 759.5 nm and their off-lines at 684 and 757.5 nm. The recorded images were analysed using the Fraunhofer line discrimination FLD technique to extract the SICF from the solar reflectance in the recorded images. The chl fluorescence image ratio red:far-red, F687:F760 was computed and correlated with the laser-induced chl fluorescence LICF ratio F685:F735 determined by point monitoring, chl content variation, and the net photosynthetic rate Pn. The scatter plot of the F687:F760 image ratio showed good discrimination between different levels of CMD infection as evidenced by the high sensitivity and specificity values. It is observed that the fluorescence image ratio F687:F760 has a good correlation with Pn coefficient of determination R2 = 0.85, chl content R2 = 0.82, and the LICF ratio F685:F735R2 = 0.80, thereby highlighting the potential of the SICF image ratio in the discrimination of CMD infection. The results clearly indicate that changes in the red:far-red fluorescence image ratio due to CMD stress can easily be detected at an early stage and the technique has great potential for monitoring the health of crops and vegetation from proximal sensing platforms.

Batch ethanol production from cassava (Manihot esculenta Crantz.) flour using Saccharomyces cerevisiae cells immobilized in calcium alginate

Abstract: The objective of this research was to saccharify cassava flour by acid-acid and acid-enzyme hydrolysis and further conversion of the resulting sugar into ethanol by fermenting with the immobilized (in Ca-alginate) cells of Saccharomyces cerevisiae. The saccharification resulted in higher total sugar recovery by acid-enzyme hydrolysis (72.88 %) than by enzyme-enzyme hydrolysis (58.1 %). Further study on ethanol production was carried out using the hydrolysate obtained from acid-enzyme hydrolysis. The growth of the yeast started in the log phage and maximum ethanol (189 ± 3.1 g ethanol/kg flour) production was achieved with 94.74 ± 2.187 % sugar conversion during the stationary phase.

Ultrastructural and Starch Digestibility Characteristics of Sweet Potato Spaghetti: Effects of Edible Gums and Fibers

Abstract: Considering the importance of pasta as a food having low starch digestibility, and the global increase in diabetes, an attempt was made to develop low glycaemic spaghetti from sweet potato incorporating gums and fibers. Gums such as guar, xanthan, and locust bean were incorporated at 0.5, 1.0, and 1.5 g/100 g mix while the fibers such as apple, oat, and wheat were incorporated at 10 and 20 g/100 g mix levels along with 1.0 and 1.5 g/100 g of xanthan gum, respectively. Gum fortified spaghetti retained more protein on cooking than fiber + xanthan gum fortification. Higher swelling index was observed for gum fortified spaghetti than fiber + xanthan gum fortification, whereas cooking loss followed a reverse pattern. Lowest in vitro starch digestibility was observed for xanthan gum (1.5%) fortification, which was significantly less than the fiber + xanthan gum fortification. Resistant starch was retained to a high extent in the fortified spaghetti. The estimated glycaemic index for control spaghetti was 66.62,...

Purification and synergistic antibacterial activity of arginine derived cyclic dipeptides, from Achromobacter sp. associated with a rhabditid entomopathogenic nematode against major clinically relevant biofilm forming wound bacteria.

Abstract: Skin and chronic wound infections caused by various pathogenic bacteria are an increasing and urgent health problem worldwide. In the present investigation ethyl acetate extract of an Achromobacter sp. associated with a Rhabditis entomopathogenic nematode (EPN), displayed promising antibacterial property and was further purified by silica gel column chromatography to get three different cyclic dipeptides (CDPs). Based on the spectral data and Marfey's analyses, the CDPs were identified as cyclo(D-Leu-D-Arg) (1), cyclo(L-Trp-L-Arg) (2), and cyclo(D-Trp-D-Arg) (3), respectively. Three CDPs were active against all the 10 wound associated bacteria tested. The significant antibacterial activity was recorded by CDP 3, and highest activity of 0.5 μg/ml was recorded against Staphylococcus aureus and Pseudomonas aeruginosa. The synergistic antibacterial activities of CDPs and ampicillin were assessed using the checkerboard microdilution method. The results of the current study recorded that the combined effects of CDPs and ampicillin principally recorded synergistic activity. Interestingly, the combination of CDPs and ampicillin also recorded enhanced inhibition of biofilm formation by bacteria. Moreover, CDPs significantly stimulate the production of IL-10 and IL-4 (anti-inflammatory cytokines) by human peripheral blood mononuclear cells. CDPs do not make any significant effect on the production of pro-inflammatory cytokines like TNF-α. The three CDPs have been studied for their effect on intracellular S. aureus in murine macrophages (J774) using 24 h exposure to 0.5X, 1X, and 2X MIC concentrations. Significant decrease in intracellular S. aureus burden was recorded by CDPs. CDPs also recorded no cytotoxicity toward FS normal fibroblast, VERO, and L231 normal lung epithelial cell lines. Antimicrobial activity of the arginine containing CDPs against the wound associated bacteria is reported here for the first. Moreover, this is also the first report on the production of CDPs by Achromobacter sp. Finally, we conclude that the Achromobacter sp. is an incredibly promising source of natural bioactive secondary metabolites especially against wound pathogenic bacteria that may receive significant benefit in the field of human medicine in near future as topical agents.

Inheritance of gynoecism in cucumber (Cucumis sativus L.) using genotype GBS-1 as gynoecious parent

Abstract: The inheritance pattern of gynoecious sex expression in cucumber was studied by utilizing a gynoecious line (GBS-1) and two monoecious lines (Pusa Uday and Punjab Naveen). Crosses were made between gynoecious line (GBS-1) and monoecious lines (Pusa Uday and Punjab Naveen). The F1 and F2 population along with parental lines were evaluated to study the inheritance of this trait. All F1 hybrids showed gynoecious sex in both crosses and in the F2 generation, the observed distribution of plant phenotypes fitted the expected mendelian ratio of 3 (gynocious plant) : 1 (monoecious plant). The segregation of plant sex types suggested monogenic dominant control of gynoecious sex form in cucumber using genotype GBS-1.

Morphological, pathological and molecular characterization of Phytophthora colocasiae responsible for taro leaf blight disease in India

Abstract: The oomycetous fungus Phytophthora colocasiae that causes taro leaf blight is one of the most devastating diseases of taro and is widely distributed in India A combination of morphological (colony morphology, mating type, pathogenicity, metalaxyl sensitivity) and molecular techniques (rDNA ITS sequencing and Start codon targeted polymorphism, ScoT analysis) was used to characterize 50 isolates of P colocasiae obtained from different locations in India Considerable differences in morphological parameters were observed ScoT analysis revealed high polymorphism among the isolates This study confirms that isolates of P colocasiae are highly dynamic in nature and a considerable degree of diversity exists among them A detailed knowledge of the morphological and molecular characters of P colocasiae will help in developing suitable control strategies against the taro leaf blight disease

Micropropagation for Rapid Multiplication of Planting Material in Cassava (Manihot esculenta Crantz)

Abstract: Rapid multiplication of planting material in cassava through tissue culture techniques such as shoot initiation, micropropagation and hardening was studied in cassava variety Sree Padmanabha. The effect of nodal segments from axillary bud of the field grown cassava cultured in Murashige and Skoog’s basal medium supplemented with different concentrations and combinations of 6- Benzylaminopurine (BAP) and Naphthalene acetic acid (NAA) were evaluated based on different parameters viz., number of shoots, number of roots, number of leaves and number of nodes. Minimal risk of contamination was observed with sterilization in 0.1% HgCl2 for 7 min, which was found to be an effective surface sterilant. For in vitro regeneration using apical node as explant, MS media with 0.3 mg l-1 NAA was found to be the best in terms of shoot having three nodes. When in vitro shoots were inoculated in MS media with 0.1 mg l-1 NAA, rooting was the most profuse. Nodal explants took one month for development into plantlets having three nodes. Potential number of planting material production from one nodal explant using micropropagation techniques was estimated to be ranging from 16,000 to 17,000 in one year period. Well rooted in vitro plantlets in sterilized vermiculite with 4-5 cm length were found suitable for hardening and subsequent transplanting, which gave 91% success after two months of hardening.

Carbon and Nitrogen Mineralization and Humus Composition Following Municipal Solid Waste Compost Addition to Laterite Soils under Continuous Cassava Cultivation

Abstract: A glasshouse incubation experiment was conducted to study the carbon (C) and nitrogen (N) mineralization of municipal solid waste compost (MSWC) added at differential rates to a laterite soil where cassava has been continuously cultivated for the past 10 years. The rate of C mineralization from added substrates increased with increasing rates of addition of MSWC. Available N significantly increased with increase in the rate of application of MSWC. There was a decreasing trend in E465/E665 ratio of humic acid as we increased the rate of application of MSWC from 2.5 to 20 t ha−1. The Cross Polarization Magic Angle Spinning (CPMAS) 13C NMR spectral analysis revealed that there are differences in the rate of humification of added MSWC, and application of MSWC at 15 t ha−1 resulted in least humification with the greatest alkyl C, lowest aromatic C, and greater O-alkyl C content. The decomposition rate (R) was found to be greater for this treatment. The residual C in soil was found to increase over time coincid...

Long-Term Effect of Lime, Mycorrhiza, and Inorganic and Organic Sources on Soil Fertility, Yield, and Proximate Composition of Sweet Potato in Alfisols of Eastern India

Abstract: A field experiment was conducted for five kharif seasons (2006–2011) in an Alfisol to study the effect of integrated use of lime, mycorrhiza, and inorganic and organics on soil fertility, yield, and proximate composition of sweet potato. Application of graded doses of nitrogen, phosphorus, and potassium (NPK) significantly increased the mean tuber yield of sweet potato by 44, 106, and 130 percent over control. Green manuring along with ½ NPK showed greater yield response over that of ½ NPK. The greatest mean tuber yield was recorded due to integrated application of lime, farmyard manure (FYM), NPK, and MgSO4 (13.69 t ha−1) over the other treatments. Inoculation of mycorrhiza combined with lime, FYM, and NPK showed a significant yield response of 10 percent over FYM + NPK. Conjunctive use of lime, inorganics, and organics not only produces sustainable crop yields but also improve soil fertility, nutrient-use efficiency, and apparent nutrient recovery in comparison to NPK and organic manures.

Purification and identification of an antibacterial protein from the symbiotic bacteria associated with novel entomopathogenic nematode, Rhabditis ( Oscheius ) sp.

Abstract: Entomopathogenic nematodes (EPN) belonging to the families steinernematidae and heterorhabditidae and their symbiotic bacteria Xenorhabdus and Photorhabdus are well-known as biological control agents and are found to produce a wide range of bioactive secondary metabolites. Studies carried out at the Central Tuber Crops Research Institute (CTCRI) on entomopathogenic nematodes resulted in the identification of novel EPN belonging to the family Rhabditidae. This study reports the purification of a high molecular weight antibacterial protein from culture filtrates of a bacterium (Bacillus cereus) symbiotically associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species, maintained at CTCRI laboratory. Fermentation conditions were standardized and optimum antibacterial activity was observed in tryptic soy broth after 48 h incubation at 30 °C. The aqueous extracts yielded antibacterial proteins which were purified by ammonium sulfate precipitation followed by ion exchange chromatography and size exclusion chromatography. Native gel electrophoresis indicated an active protein of molecular mass 220KDa which resolved into a major band of 90 kDa and a minor band of about 40 kDa on SDS-PAGE. The 90 kDa protein showed antibacterial activity and was further analysed by MALDI TOF—MS/MS. The protein was identified as a TQXA (Threonine–glutamine dipeptide) domain containing protein from Bacillus cereus. The protein was found to be active against Bacillus subtilis MTCC2756, Staphylococus aureus MTCC902 and Escherichia coli MTCC 2622 and was thermally stable.

Influence of Age of Explants and Genotype on Somatic Embryogenesis in African and Indian Cassava Cultivars

Abstract: Potential of eight cassava cultivars viz., TME3, TME4, TMS 30572, TMS 1089A, 96/0160, Albert,Kibaha and H165 for initiating somatic embryos was studied. Two different explants, young leaf lobe pre-cultured on Murashige and Skoog (MS) medium and axillary bud pre-cultured on MS medium containing BAP were tried. The age of explants and type of cultivar highly influenced the frequency and quantity of somatic embryos. Axillary buds of cv. Albert and young leaf lobes of cv. H165 responded well, while the same results were observed for conversion and development. Hardening and establishment in green house was close to 100% for all the cultivars under study. This paper discusses the effect of juvenility of the explants used, duration of pre-treatments and culture on embryogenesis medium, cultivar and its preference of explant, health of the mother plants, on successful regeneration of cassava via somatic embryogenesis, which could be very resourceful for friable embryogenic calli production and successful genetic transformation.

Effects of Organic and Inorganic Fertilizers on Yield of Elephant Foot Yam and Soil Enzymes Activity

Abstract: A field experiment was carried out for two consecutive years during 2011and 2012, to study the effects of organic and inorganic fertilizers on leaf area and yield of elephant foot yam and soil enzyme activities. The experiment was conducted at the Regional Centre of Central Tuber Crops Research Institute, Bhubaneswar using randomized block design (RBD) with three replications. The experiment comprised of eight treatments involving organic and inorganic fertilizers. Highest leaf area per plant was recorded with the application of FYM 25 t ha-1 and the application of FYM 10 t ha-1 with NPK@ 100- 60-100 kg ha-1. These treatments also resulted in higher light interception and offered lower soil resistance. The application of FYM 10 t ha-1 + NPK@ 100-60-100 kg ha-1 and FYM 25 t ha-1 has produced 105.7% and 97.1% higher corm yield respectively, over control. These treatments maintained higher soil enzyme activities despite poor post harvest soil nutrient status. In alfisols, medium duration elephant foot yam can be cultivated profitably under protective irrigation with the application of FYM 10 t ha-1 + NPK@ 100-60-100 kg ha-1 or FYM 25 t ha-1 with enhanced soil enzyme activity.

An antimicrobial phthalate derivative from bacillus cereus, the symbiotic bacterium associated with a novel entomopathogenic nematode, rhabditis (oscheius) sp

Abstract: Objective: To isolate and identify the bioactive metabolites from the culture filtrates of a bacterium ( Bacillus cereus) symbiotically associated with a novel entomopathogenic nematode Rhabditis ( Oscheius ) species. Methods: The bacterium was cultured in three different media and the antimicrobial activity was determined by the well diffusion assay. The ethyl acetate extract of the cell free culture filtrate was then purified by silica gel column chromatography and thin layer chromatography. Identification of the active metabolite was done with HPLC, GC-MS and LC-MS. Results : The cell free culture filtrate of a nematode symbiotic bacterium showed both antibacterial and antifungal activities. Fermentation conditions were standardized and optimum antibacterial activity was observed in tryptic soy broth at 72 h of incubation at 30 °C. When the ethyl acetate extract was purified by silica gel column chromatography and thin layer chromatography, an active fraction was obtained which was subjected to HPLC analysis along with GC-MS and LC-MS leading to the identification of a major compound Bis (2-ethyl hexyl) phthalate. The compound was active against Gram positive bacteria Bacillus subtilis MTCC2756, Staphylococus aureus MTCC902, Gram negative bacteria Escherichia coli MTCC 2622 and fungi such as Aspergillus flavus MTCC27 7, Candida albicans MTCC183, Fusarium oxysporum MTCC 284, Rhizoctonia solani MTCC 4634. Conclusion : Bis (2-ethyl hexyl) phthalate was identified as one of the metabolites produced by a nematode symbiotic bacterium associated with a novel entomopathogenic nematode Rhabditis ( Oscheius ) species. Thus similar compounds isolated from novel entomopathogenic bacteria would pave the way for identifying new drugs for the pharmaceutical and agricultural sector.

Transcriptome profiling of in vitro lines propagated from corm bud tip of elephant foot yam (Amorphophallus paeoniifolius) approves complete potyviruses elimination

Abstract: The most characterised Dasheen mosaic virus and many other unreported putative viruses are involved in the mixed viral mosaic infection of elephant foot yam (Amorphophallus paeoniifolius). The in vitro propagation of corm bud tips for virus free plantlet production was carried out in three different culture phases consisting of callusing, shoot regeneration and rooting. A 100 % survival rate was recorded on hardening in sand: soil: coir pith (1:1:1) mixture. A total of 84 % of regenerated plantlets were found to be virus free on indexing of 21 in vitro lines with species specific/genus specific serological and molecular diagnostic techniques. Transcriptome sequencing was carried out for two randomly selected in vitro plants and a mosaic infected field sample. Not any of the known potyviruses were traced in the transcriptome profiles of supposed virus free plants thus confirming the complete potyviruses elimination. Disease symptoms or re-occurrence was not observed in the hardened virus-free lines of the plant.

Productivity of Cassava (Manihot esculenta) as affected by drip fertigation in humid tropics

Abstract: Field experiments were carried out at Central Tuber Crops Research Institute, Kerala, India during three seasons, 2009-2010, 2010-2011 and 2011-2012 to investigate the response of cassava to precision approaches in irrigation and fertigation. The experiments were laid out in split plot design with three replications. The main plots included three levels of drip irrigation viz., (I 1 - irrigation at 100% pan evaporation (PE), I 2 - 80% PE and I 3 - 60% PE). The sub plots comprised of three fertigation schedules viz., three ratios of recommended nitrogen and potassium fertiliser doses applied at growth stages of 1-40 days, 40-80 days and 80-120 days (F 1 -50:30:20, F 2 -30:50:20 and F 3 -50:40:10). Minisetts of cassava variety 'Sree Vijaya' was planted at a distance of 60 x 45 cm during the dry spell (Dec- May) in all the years. Results indicated that irrigation at 100% PE yielded maximum tuber yield in all the seasons (43.9 t ha -1 ). There was no significant difference in yield among the fertigation schedules. However, interaction effects showed that I 1 F 1 resulted in better growth characters, yield attributes and yield followed by I 1 F 3 . On an average, 280 mm, 224 mm and 168 mm of water were applied in I 1 , I 2 and I 3 irrigation levels respectively during the growing season. Water use efficiency determined was also higher for irrigation at I 1 level of irrigation.

Genetic Diversity of Phytophthora colocasiae Causing Taro Leaf Blight: Analysis Using Start Codon Targeted (SCoT) Polymorphism

Abstract: The Oomycetous fungus Phytophthora colocasiae that causes taro leaf blight is one of the most devastating diseases of taro and is widely distributed in India. Cultural and molecular techniques were employed for assessing the genetic variability among 30 isolates of P. colocasiae obtained from different geographical origins of India. Cultural characters like pathogenicity assay, mating type and metalaxyl sensitivity showed variation among isolates. Eight Start Codon Targeted Polymorphism (SCoT) markers produced 121 reproducible fragments with 100% polymorphism. The average value of the number of observed alleles, the number of effective alleles, mean Nei’s genetic diversity, and Shannon’s information index were 2.00 ± 0.00, 1.58 ± 0.30, 0.34 ± 0.13, and 0.51 ± 0.16, respectively. Analysis of molecular variance (AMOVA) showed that 89 % of the diversity was present within population of P. colocasiae . Dendrograms based on the molecular data using the unweighted pair group method with arithmetic mean (UPGMA) classified the P. colocasiae isolates into two major clusters. Cophenetic correlation coefficient between dendrogram and original similarity matrix were significant for SCoT marker (r = 0.904). The results of this study displayed a high level of genetic variation among the isolates irrespective of the geographical origin. The possible mechanisms and implications of this genetic variation are discussed.

Isolation and Characterization of N Fixing Bacteria from Elephant Foot Yam (Amorphophallus paeoniifolius (Dennst.)Nicolson) Growing Regions of South India

Abstract: Isolation and screening of 130 bacteria from the rhizosphere region of elephant foot yam ( Amorphophallus ) growing area of South India for their ability to fix atmospheric nitrogen ( Kjeldhal technique) resulted in the identification of 62 isolates having varying levels of nitrogen fixing ability in Jensen's nitrogen free medium. The most potent nitrogen fixing isolates were tested for their efficiency to release plant growth promoting substances like indole acetic acid (IAA), ammonia (NH 3 ), hydrogen cyanide (HCN) and catalase enzyme. Morphological and molecular characterization of the two potent bacterial strains led to the identification of them as Bacillus cereus strain ANctcri-1 (HQ286640) and Pseudomonas aeuroginosa ANctcri-11 (JX974833). A study on the effect of various physiological conditions on growth of this potent bacteria revealed their facultative alkaliphilic halo tolerant nature.

A Highly Sensitive Nested-PCR Method Using a Single Closed Tube for the Detection of Colletotrichum gloeosporioides causing Greater Yam Anthracnose

Abstract: Greater yam is an important species of yam grown in different parts of India. Anthracnose or die back disease caused by Colletotrichum gloeosporioides reduces the yield up to 90 per cent. The pathogen survives in the soil debris and transmits the disease to the next season through tubers. In this study, a sensitive method for the specific diagnosis of C. gloeosporioides in soil and planting material was developed. The standard nested PCR previously described was re-standardized to run a single nested PCR in a closed tube. The problems of cross contamination and the increased risk of PCR product contamination, while handling the product of first PCR could be avoided. This technique could be achieved by adjusting the concentration of primers and the annealing temperature along with the standardization of PCR cycles so as to produce a single amplicon without compromising the limit of detection and specificity. The lowest amount of DNA that could be determined by this method was 200 pg ml-1.

A Comparative Study on the Resistant Starch Content in Starches from Different Botanical Sources in Relation to their Physicochemical Properties

Abstract: Resistant starch (RS), a functional food ingredient and a third type of fiber that provides the benefits of both insoluble and soluble fibers , bags attention due to its unique functional and health attributes. The aim of this study was to investigate the resistant starch content in the starch isolated from different botanical sources such as cereals (maize, rice, oats, wheat, barley), legumes (lentil, mung bean), vegetable (raw banana), and roots & tubers (potato, cassava, sweet potato and arrowroot). The rapidly digestible (RDS), slowly digestible (SDS) and RS contents in the starch samples were determined and related with their physiochemical and functional properties. The study showed that the starch from different sources varied significantly in their chemical, physical and functional properties as well as in RS content. The highest RS content was observed for lentil starch (5.3%) and lowest for starch from oats (1.3%). In general, RS content was lower for starch extracted from roots and tubers compared to that from cereals and legumes. The RDS content of maize starch was the highest (95.2%) and that of barley starch was the lowest (69.5%), whereas the SDS showed a reverse trend. The RDS and RS contents showed a positive correlation with amylose content in the starch. The highest amylose content was possessed by lentil starch (28.5%) which also showed the highest RS content among all the selected starches.