Yam Tubers Research Articles

Antifungal Activities and Phytochemical Analysis of Leaf Extracts of Azadirachta Indica and Tridax Procumberns on Fungi Associated with DioscoreaAlata (White Yam) Tuber Rot in Storage

Antifungal Activities and Phytochemical Analysis of Leaf Extracts of Azadirachta Indica and Tridax Procumberns on Fungi Associated with DioscoreaAlata (White Yam) Tuber Rot in Storage

English

The objective of this work was to develop and characterize biodegradable starch films at 14 and 21 days of fermentation, aiming to develop packaging with added value. For the extraction of starch, yam tubers were washed, crushed, filtered and fermented for 14 and 21 days, and then filtered and dehydrated. Water-starch-glycerol mixtures were prepared in a randomized design using a factorial scheme (5x2), with five concentrations of glycerol (0, 0.5, 1.0, 1.5 and 2.0 mL) using two durations (14 and 21 days) and 6 replicates. The analyzed parameters were thickness, density, solubility, sorption kinetics, humidity, scanning electron microscopy characteristics and color. Analysis of variance revealed significant difference at the 1% level for the interaction of fermentation time and glycerol concentration for the studied variables. Overall, a 21 day fermentation period gave better characteristics of density, humidity and color and the addition of plasticizer positively influenced the parameters studied.   Key words: Gelatinization, packaging, fermentation, starch.

Processing of Yam Paste (Amala): A Product of Fermented Yam (Dioscorea rotundata) Flour

This study was designed to evaluate the processing of yam paste (amala): A product of fermented yam (Discorea rotundata) flour. The sliced yam samples were fermented for 72 hours. The microorganisms were isolated and identified. The pH, TTA, temperature, proximate, anti-nutrient, mineral composition and sensory analyses of the sample were determined. The microbial loads increased with fermentation time. The isolates identified were Pseudomonas aureginosa, Staphylococcus aureus, Bacillus subtilis, Lactobacillus plantarum, Lactococcus lactis, Aspergillus niger, Saccharomyces cerevisiae, Fusarium oxysporium, and Candida tropicalis. pH decreased from 6.4 to 4.9 while TTA and temperature increased from 0.16 to 4.24% and 28oC to 34oC. The crude protein (2.46%) and moisture contents (12.32%) increased in the fermented sample with a decrease in ash (0.70%), fat (0.19%) and carbohydrate contents (80.76%). The saponin and phytate decreased from 31.29 to 11.45mg/g and 11.12 to 5.77mg/g. The fermented sample showed an overall acceptability. Improvement in the nutritional and reduction in antinutritional contents of the fermented sample suggests its usefulness as a food source for humans. The microorganisms associated with fermented yam tubers, processing of yam tubers into flour to produce amala and determining the nutritional and antinutrient content of both unfermented and fermented yam. The fermentation process improving the quality and nutrient content of the yam tubers suggested the method as more promising in producing food for humans.

The Binding Affinity of Small Molecules with Yam Tyrosinase (Catechol Oxidase): A Biophysical Study.

Yam tyrosinase has become an economically essential enzyme due to its ease of purification and abundant availability of yam tubers. However, an efficient biochemical and biophysical characterization of yam tyrosinase has not been reported. In the present study, the interaction of yam (Amorphophallus paeoniifolius) tyrosinase was studied with molecules such as crocin (Crocus sativus), hydroquinone, and kojic acid. Surface plasmon resonance (SPR), fluorescence spectroscopy, and circular dichroism techniques were employed to determine the binding affinities and the changes in secondary and tertiary structures of yam tyrosinase in the presence of four relevant small molecules. Hydroquinone and crocin exhibited very low binding affinities of 0.24 M and 0.0017 M. Due to their apparent weak interactions, competition experiments were used to determine more precisely the binding affinities. Structure-function interrelationships can be correlated in great detail by this study, and the results can be compared with other available tyrosinases.

Comparative Studies on the Susceptibility of Three Tubers of Dioscorea Species to Dry Rot in Anyigba, Kogi State

Various yam species are cultivated but white yam (Dioscorea rotundata Poir.), water yam (Dioscorea alata L.) and yellow yam (Dioscorea cayenensis Lam.) are among the most cultivated in Nigeria. The Susceptibility of three tubers of Dioscorea species (D. rotundata, D. alata and D. cayenensis) to dry rot pathogens was investigated. Isolation was made from rotted tuber tissues, followed by pathogenicity test and identification of isolates; two fungal species Aspergillus niger and Rhizopus stolonifer were isolated and identified as the major fungi causing yam tuber dry rot in the study area. There was significant difference (P<0.05) in the susceptibility of the various Dioscorea tuber species studied to rot caused by Aspergillus niger [D. rotundata (20mm), D. alata (11mm) and D. cayenensis (3.5mm)] and Rhizopus stolonifer [ D. rotundata (17.5mm), D. alata (10mm) and D. cayenensis (2mm)]. The phytochemical contents of the three tubers of Dioscorea species examined also varied significantly, with the bioactive substances of D. cayenensis and D. alata relatively higher when compared to D. rotundata. Therefore, this research reveals that three metabolites; Saponin, Flavonoid and Tanin constitute the major trait for resistant ability of D. cayanesis and D. alata to dry rot causing pathogen. Therefore, it is necessary that the differences in susceptibility be considered when developing yam barns. Also, researchers should work on genetically improving the susceptible white yam (D. rotundata) which is commonly eaten by millions of Nigerians with a possibility of increasing the quantities of the deficient phytochemicals.

Histological Study of the Polarity of Yam Tuber (Dioscorea spp.) at the Beginning of Tuberization

Yam, like most roots and tubers, has a tissue variation that is responsible for the difference in cooking observed during culinary preparations. In order to understand the origin of this variation, this study was conducted through optical microscope and SEM observation of the beginning of tuberization. The local variety named Kponan of Dioscorea cayenensis-rotundata was used. The days after the beginning of the tuberization, the protrusion of the stem base intensified and gives rise to the tuber. The histological study of the onset of tuberization revealed once again the existence of a longitudinal growth gradient whose point of growth is the apex and the sense of maturity of the distal part at the proximal end. The cells birth at the apex and differ a little more towards the middle part of the tuber. The apex is the driving zone for the tuber's lengthwise growth. The cambial cells ensure this growth in length and thickness of the tuber. The tuber's growth activity decreases from the distal part to the proximal one. The distal part contains more vacuolated cells thus rich in water and less starch than the middle and proximal parts. The cell wall is thin and less lignified. The cambium generates cells at the lower end of the apex. These very vacuolated cells differentiate and will form the median and proximal parts of the tuber. The distal part will remain immature compared to the other two parts. This could explain the low dry matter and the origin of rejection or elimination of the distal part during culinary operations.

PREFERENSI PERTUMBUHAN BIBIT GEMBILI [Dioscorea esculenta (Lour.) Burkill] ASAL BAHAN TANAM DAN TEKNIK PENANAMAN BERBEDA

Lesser yam (Dioscorea esculenta (Lour.) Burkill) tubers have two important roles in conventional cultivation, as the food as well as the propagation material. The stem cuttings technique is reported can not produce tubers, while micropropagation is less efficient due to the need of large capital, experts, and specific tools. The other hand, farmers are less interested in cultivating this commodity. It has been reported that mini tuber sett can be used for propagation, but it has not been able to explain the growth preferences in each part of the tuber and its effect on yield. The research aims to provide information about the growth preference of lesser yam seedlings from different planting materials and planting techniques and their effects on yields. The research was carried out in Research Center for Biology, LIPI, Cibinong. The experiment was arranged based on split plots with tubers (apical and basal parts) as the main plot and planting position (vertical and horizontal) as subplots. Each treatment was replicated 3 times, with 5 samples for each replication. The results revealed that the apical part produced better shoots and roots than the basal section. The apical dominance of the lesser yam tuber was very high. It is herefore buds that form in the apical tended to grow faster. This section also produced tuber with a better character. With this information, farmers recommended to use planting materials from the apical part of the tuber with horizontal planting position.

Formulation of Natural Fortifiers from Readily Available Materials for Nutrient Enrichment of Organic Fertilizers

Studies have shown that organic fertilizer, a product of biodegradable organic matter, is not popular among Nigerian farmers because of its low quality. To alleviate this problem, this study was designed to explore the effect of nutrient-rich materials on quality of fertilizer made from market organic wastes. It adopted an experimental study design, comprising organic fertilizer preparation, fortification with natural fortifiers, farm plot experiments and laboratory analyses. The experiment was laid out in a randomized complete block design with factorial arrangement and three replications. The main plots comprised three crops - maize (cereal), soybean (legume) and yam (tuber) while five different fortified organic fertilizers at three rates of applications -2.0, 2.5, and 3.0 ton/ha and control (organic fertilizers without fortification) - formed subplots. Nutrient-rich materials sourced from animal, plant and rock changed the chemical composition of organic fertilizer made from market wastes and yielded better agronomic performances than the synthetic fertilizer. Hence, fortification of organic fertilizer with natural materials which are readily available and environmentally friendly should be promoted among the farmers.

Nutritional Characteristics and Potential Applications of Flour Prepared from Indonesian Wild White Yam (Dioscorea esculenta L.)

Gembili or wild white yam (Dioscorea esculenta L.) is one of underutilized tubers that can be found during dry season in Indonesia and other Southeast Asian countries. Although it has been consumed as staple food by people for centuries during famine, no further studies have been conducted to explore its potentials in food applications. This work aims to study the preparation, characterization and potential analysis of Gembili flour for use as raw material in novel foods development. Creamy white flour was obtained from white yam tuber from milling and sieving of dried tuber chips. The flour has water content about 12.08%, which is acceptable for storage. No lipid was detected. In addition, the protein, ash, and fiber content of the flour were respectively 3.00%, 1.27%, and 9.04%. The carbohydrate and amylose contents of the flour were 86.69% and 29.92% indicating its suitability for energy source. As expected, the cyanide content is very low of about 1.688 ppm suggesting that it is safe for consumption. Refer to those properties, Gembili flour can be a promising raw material for the preparation of bakery, cookies, noodle and confectioneries.Keywords: proximate composition, flour, white yam, food, preparation

Ketahanan Padi Transgenik Db1 Terhadap Wereng Coklat (Nilaparvata lugens Stal.) Biotipe 3 (Resistance of Db1 Transgenic Rice to Biotype 3 of Brown Planthopper (Nilaparvata lugens Stal.)

Brown planthopper has been recognized as a primary pest of rice in Indonesia and most Asian countries. Developing rice lines resistant to this pathogen is an effective and environmentally friendly approach. Rice cv. Taichung 65 has been transferred with Db1 gene from yam tuber Dioscorea batatas , to improve its resistance to insect pathogen. The rice plant, however, is not been known yet of its resistance to biotype 3 of brown planthopper from Indonesia. The objective was to obtain resistance level of Db1 transgenic rice against biotype 3, the brownest planthopper attacking rice. The experiment was arranged in randomized block design, and some tests performed were screening resistance, honeydew test, and the oviposition preference. Results indicated that Db1 Taichung transgenic rice had improved resistance level as compared to its wild type; from very susceptible to susceptible. Db1 transgenic rice line had a lower resistance level compared to those of cv. PTB33, Rathu Heenati, Ciherang, Babawee, IR64, dan Cisadane. It could be seen from a higher amount of honeydew excreted and a number of an egg laid by brown planthopper compared to those of tested cultivars. It is concluded that DB1 transgenic line is susceptible, then it is not sufficient to control brown planthopper specifically biotype 3.

Mobility of Pratylenchus coffeae in segmented soil columns submitted to water flows and plant stimuli

The root-lesion nematode Pratylenchus spp. causes a high-severity disease, promoting high economic losses in various crops of agricultural importance. The nematode control is difficult, especially after introduction into the area. Studies on the migration of this parasite in the soil are scarce. However, understanding nematode behavior in the soil is fundamental to increase the efficiency of management practices, especially in irrigated agriculture. This study aimed to evaluate the influence of water flow and plant stimulus on Pratylenchus coffeae mobility in segmented soil columns. The columns were segmented into 11 rings of 1 cm long filled with washed sand, one of the ends exposed to a bait, and submitted to flows of 0, 3, 7 cm3/min of water. Baits for nematode attraction and repelling consisted of sectioned tubers of yam (Dioscorea cayennensis) and cut leaves of neem (Azadirachta indica), respectively, and the absence of baits as the control. Nematodes were injected into the central segment of the column, and migration and presence in water leaching were determined five days after soil infestation. Mobility of P. coffeae varied with water flow and bait type. In the absence of water flow, nematodes migrated in the opposite direction to the neem baits, but migration was well distributed in the presence of yam baits, with specimens present in all column segments. The nematode had significantly higher resistance to water flow of 3 cm3/min in the presence of yam baits. No nematodes were found in the water leached at flows of 3 and 7 cm3/min in the absence of bait. Key words: Azadirachta indica. Dioscorea cayennensis. Lesion nematode. Soil dispersion.

Evaluation of efficacy of false yam (Icacina oliviformis) as surface protectant against rot pathogens of white yam (Dioscora rotundata Poir)

Rots in yam tubers are the dominant cause of postharvest losses. Therefore, studies were con­ducted to identify the rot-causing organisms in yam and to evaluate the efficacy of false yam (Icacina oliviformis) plant extracts as surface protectants in the storage of yam. The experiment was laid out in a completely randomized design (CRD) design with five treatments (fruit, root and leaf extract of false yam, Mancozeb and tap water) replicated three times. Two concen­trations (50% and 100%) of each extract were also tested. Species were identified based on the structural features, the characteristics and properties of the spore and mycelium. A spore suspension of yam rot fungi was sprayed on healthy yam tubers that had been pretreated with the extracts. Results showed that fungi isolated from rotted yams were Aspergillus niger, A. fla­vus and Penicillium sclerotigenum. Leaf extracts (both 50% and 100%) had the highest growth inhibitions on all the three fungi isolated in vitro. Tubers treated with root and leaf extracts of false yam had a decreased tuber rot lengths of 1.80 mm2 and 2.17 mm2, respectively. The leaves and roots of false yam can be used as a surface protectant of yam in place of Mancozeb. Keywords: Icacina oliviformis; Dioscora rotundata; Mancozeb; Pathogenicity; Aspergillus spp.

Distribution and virulence of fungal species isolated from yam (Dioscorea spp.) tubers in three agroecological zones of Nigeria

Field surveys were conducted in 2012 and 2013 to evaluate the distribution and virulence of fungal isolates associated with tuber rot disease among yam (Dioscorea spp.) producing agroecological zones (AEZs) of Nigeria. A total of 70 and 66 farmers’ fields were surveyed in 2012 and 2013, respectively among three yam species, Dioscorea rotundata, D. alata and D. cayenensis. Fifteen rotted samples were randomly collected per each yam species in fourteen districts across the humid rainforest (HF), the derived savanna (DS) and the southern Guinea savanna (SGS) agroecologies. Twenty-one fungal species were isolated in the HF, 18 species in the DS and 16 in the SGS. The highest rot severity was in HF agroecology in the D. rotundata which varied from 27.2% to 65.7% in 2012 and from 21.1 to 57.4% in 2013, while the SGS agroecology had the least severity. Lasiodiplodia theobromae was the most virulent pathogen with lesion diameter of 26.8–42.1 mm at 14 days after inoculation. Findings provide baseline information for the formulation of management strategies for yam tuber rot disease in Nigeria.

Abstract 4431: Cytotoxic effects of the Jamaican yam tuber in hormone-sensitive cancers and its potential use in green nanotechnology formulation

Abstract Historically, plant materials have been widely explored for their anti-proliferative effects against a variety of cancer cells, with many of them proving to be very effective. Additionally, their efficacy has been seen in the specific field of targeted cancer therapy. The use of plants for therapeutic purposes in place of or with traditional medicine is collectively referred to as complementary and alternative medicine (C.A.M). Several Jamaican Yam species have shown to be useful as C.A.M in the treatment of certain medical conditions such as diabetes, hypercholesterolemia and cancer. Hormone-sensitive cancers such as breast and prostate cancer are the most frequently diagnosed malignancy and when combined, is the leading cause of cancer related deaths among the Jamaican populace. These statistics unfortunately, are also reflected in the wider Caribbean region. Currently treatment involves: surgery, radiation and androgen deprivation therapy; however, there are some cases in which mutation causes further growth of the cancer cells regardless of treatment. As such, there still remains a dire need of a more effective and lasting therapy. The aim of this study was to assess the antiproliferative effects of yam material and to also deduce a possible mechanism of action in an effort to formulate a means of targeted therapy. The results showed that an alcoholic extract of the Jamaican yam tuber (Dioscorea spp.) demonstrated anti-proliferative effects in androgen insensitive prostate cancer cell lines (IC50 of 18 ppm, 95% C.I. 24-33ppm) and invasive breast cancer cell lines (IC 50 of 28 ppm, 95% C.I 36-54ppm). Western blot assays also indicated that cell death was possibly induced through the cell cycle regulatory protein, cyclin D. The antiproliferative effects and purported mechanism of action of the yam extract against some hormone-sensitive cancer cells makes it an ideal alternative for the formulation of green nanotechnology for targeted therapy. Note: This abstract was not presented at the meeting. Citation Format: Sasha-gay A. Wright. Cytotoxic effects of the Jamaican yam tuber in hormone-sensitive cancers and its potential use in green nanotechnology formulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4431.

Effects of Storage on Physical and Viscoelastic Properties of Yam Tubers

Effects of Storage on Physical and Viscoelastic Properties of Yam Tubers

Activity of Inhibition Bacterial Pathogens from Symbiotic Yogurt of Yellow Yam Tuber with the Addition of Probiotics strains L. rhamnosus and Bifidobacterium ssp

Activity of Inhibition Bacterial Pathogens from Symbiotic Yogurt of Yellow Yam Tuber with the Addition of Probiotics strains L. rhamnosus and Bifidobacterium ssp

Chemical Composition of Essential Oil of Mondia whitei and Antifungal Activities Against Aspergillus flavus and Penicillium sp., The Mold Associated on Yams (Dioscorea rotundata Poir.) Tuber Rot

The aim of this work was to determine the chemical composition of essential oil of roots of Mondia whitei and to evaluate their antifungal potential against Aspergillus flavus and Penicillium sp. Oil was obtained by hydro-distillation and gas chromatography was used to analyze their chemical constituents. The fungi were isolated from post-harvest yams (Dioscorea rotundata) showing typical symptoms of tuber rot. Antifungal activities of the oil were tested in vitro against mycelia growth and conidia germination. In situ test was carried out on healthy yams by application of the oil after (preventive test) and before (curative test) infection with pathogens. Results showed that yield of root Mondia whitei essential oil was 2.57 % and the Menth-1-en-7-al <3-oxo-P-> was found to be the main component. Significant reduction of mycelia growth was obtained with minimal inhibitory concentration (MIC) at 500 μl/l and 525 μl/l respectively for Aspergillus flavus and Penicillium sp. This oil completely inhibited the conidia germination of Penicillium sp. with MIC at 525 μl/l while 65.38 % inhibitory was obtained at 1000 μl/l against Aspergillus flavus. In situ test showed significant reduction of necrosis of yam tuber rot. At 2500 μl/l we obtained 47.41 % and 72 % of necrosis inhibition respectively, for preventive and curative healing for Aspergillus flavus, while for Penicillium sp., we obtained at 2625 μl/l, 31.8 % and 43.07 % of the necrosis inhibition, respectively. This study demonstrated that essential oil from roots of Mondia whitei could be promising alternative for management yam tuber loose induced by mold.

Amino acid composition of wild yam (Dioscorea spp.)

Tubers of wild yam (Dioscorea alata, D. bulbifera var. vera, D. esculenta, D. oppositifolia var. oppositifolia, D. oppositifolia var. dukhumensis, D. pentaphylla var. pentaphylla, D. spicata, D. tomentosa and D. wallichi) were analyzed for its amino acids composition. Asparatic acid and glutamic acid were found to be predominant among all the investigated Dioscorea species which ranged from 5.21 to 9.36 and 3.20 to 8.12 g/100 g protein respectively. The essential amino acids such as isoleucine, phenylalanine tyrosine, histidine, isoleucine and valine were found to be more or less higher than FAO/WHO (1991) requirement pattern. Thus, the present investigation demonstrated that the Dioscorea spp. can act as a good source of amino acid

Absence of Effects of Herbicides Use on Yam Rots: A Case Study in Wulensi, Ghana

Yam farmers in Ghana have, over the years, used herbicides for weed control, particularly glyphosate. Although this has been helpful to them, there are complaints and concerns, among the yam farmers and a section of the public, that the yam tuber rots easily under the use of herbicides. This study, therefore, was set up at the field level to investigate the possibility of herbicides use causing yam rot. Two yam varieties, “laribako” and “olodo”, were grown under the conditions of chemical weed control (use of glyphosate) and manual weed control in three replicate sites in Wulensi in the Nanumba traditional area of northern Ghana. The study revealed that there was no difference in rots between herbicide treated yams and manually weeded yams, but that there was a difference in rots between “laribako” and “olodo” yam varieties. The results also showed that there was no difference in yield between herbicide treated yams and manually weeded yams. Based on the findings, it can be concluded that, there was no difference in yam rot and yield between herbicides treated and manually weeded yams, but “laribako” was more susceptible to rot than “olodo”.

Adaptation on low light intensity of lesser yam (Dioscorea esculenta) under artificial shading

Abstract. Lestari P, Utami NW, Wawo AH. 2019. Adaptation on low light intensity of lesser yam (Dioscorea esculenta) under artificial shading. Pros Sem Nas Masy Biodiv Indon 5: 374-382. Tubers can be used as an alternative food to reduce dependence on rice. Current status of lesser yam is considered rare. However, it can still be found in people's yards in some areas of Java island, especially the older generation. The high content of inulin in the lesser yam tuber makes it feasible to be one candidate potential functional food source. The planting of lesser yam in the agroforestry component has important meaning to increase the productivity of the alleyway between forest crop and ex situ lesser yam conservation. The introduction of low-input lowland cultivation can be a factor to attract the farmer to cultivate lesser yam. The experiments were prepared based on the RCBD nested design. The research is intended as a baseline data to determine the adaptation of lesser yam to low light intensity stress. The data can be applied to determine the age of main timber plant commodities that can still be interspersed with lesser yam. The study was conducted with nesting plots. The level of shade as the main plot consists of 0% shade, 25% shade, 55% and 75% shades. Organic fertilizer as a subplot consists of no fertilizer and with fertilizer. Each treatment having 3 replications consisting of 3 plant observations. Organic fertilizer gave since 2 weeks after planting with a dose of 25cc / lt every week until the plant is 3 months old. Observations were made in plant growth, yield, and physiological phases. Almost all observation variables showed shade treatment more affecting growth and production of crops than fertilizer treatment. This good growth shows that the canopy of the plant grows optimally in full light conditions. Under different shade conditions, total yields did not differ between shade levels up to 50%, but tuber production was more uniform in shade 25% and 50%. Further research is needed on the interaction of lesser yam in various timber commodities as a major component of agroforestry.