Development of micropropagation system for yam (Dioscorea spp.) using somatic embryogenesis

Inadequate availability of disease-free planting materials remains a major constraint to yam production. The tissue culture technique has been used to regenerate disease-free plantlets from pre-formed, heattreated meristems followed by micropropagation. This procedure, however, has a low multiplication ratio with an average of 1: 4 every eight weeks. Embryo production from somatic cells (somatic embryogenesis, SE) is a system in which each somatic cell can regenerate a complete plantlet. However, previous reports show low SE induction frequencies and significant variations in success rates among different genotypes while hardly any report exist for improved varieties that farmers desire, especially in Nigeria. Studies were carried out to evaluate the effects of different plant growth regulators (PGRs) on induction of somatic embryogenesis of the following genotypes: one improved Dioscorea alata (TDa 291) and three improved (TDr 95/19177, TDr 89/2665, TDr 95/18544) and one landrace (Obioturugo) of Dioscorea rotundata. Leaf, stem, and axillary bud explants were cultured in MS basal medium containing fifteen treatment combinations of 2,4-Dichlorophenoxyacetic acid (2,4-D), Naphthaleneacetic acid (NAA), Benzylaminopurine (BAP), Picloram, and Uniconazole-P (UP). The genotype TDr 95/19177 was tested for SE in Temorary Immersion Bioreactor System (TIBS). The incidence of induction of callus formation and plantlet regeneration from the three explants were recorded. Embryogenic callus induction was highest (87%) from axillary buds cultured on modified MS + 2 mg/l of 2,4-D + 1 mg/l of NAA while 1 mg/l of BAP + 9. 9 mg/l of UP had the highest percentage plantlet regeneration of 50% in TDr 95/18544 and an average of 37% across genotypes at a mean of 5 plantlets per explant. The genotype TDr 95/19177 was successfully regenerated via indirect somatic embryogenesis in the SETIS Type Temporary Immersion Bioreactor System

The impact of climate change on household food security in the Bongo District of the Upper East Region of Ghana

The study determined the impact of climate change on household food security, investigated awareness level and identified coping strategies used to mitigate negative impact of climate change in the Bongo District with emphasis on women. It was a cross-sectional survey conducted in four purposively selected farming communities in the District in the Upper East Region of Ghana. A sample size of 246 women participated in the study. Using a structured questionnaire, data were collected on socio-demographic characteristics of the participants, awareness of climate change, food consumption patterns, coping strategies and household food security. Data on rainfall and temperature for the past 30 years period in the District were obtained from the Ghana Meteorological Service. Crop yields data over a period of 21 years in the District was also obtained from the Ministry of Food and Agriculture (MOFA). The results revealed that rainfall in the Bongo District has been decreasing at - 0.3 mm per annum and maximum temperature has been increasing at 0.005 °C. More than half (62.6%) of the participants were aware of climate change in their communities. Majority (89.4%) of the participants reduced the quality and quantity of diets as coping strategy method during food shortage periods and almost all (97.2%) of the households were food insecure. Participants who reported to have observed decrease in rainfall were more likely to be food insecure (OR = 3.96; CI = 0.56 – 27.81). Participants were aware of climate change and employed reduction in the quality and quantity of diet as coping mechanism. Almost all households were food insecure. There is the need to intensify climate resistant agriculture technology such as irrigation methods to offset the negative impact of climate change on food security in the District.

Roots and Tubers Research and Development Activities in Countries of the Caribbean Community with a Focus on Cassava (Manihot esculenta Crantz)

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Search for Scutellonema bradys resistance in yams (Dioscorea spp.)

A study to examine variability in susceptibility of yams to Scutellonema bradys and to identify possible sources of resistance in Ghanaian yam germplasm (Dioscorea spp.) for use in yam improvement programmes, particularly, in West Africa was undertaken. Pot and field screening methodologies were used. In general, S. bradys and dry rot of tuber symptoms as well as tuber cracking increased during the storage period. The study showed a positive correlation between visual nematode damage and population densities in yam tubers. There was also a linear relationship between dry rot disease and tuber cracking at harvest and during storage. This confirms that S. bradys causes dry rot of tubers resulting in external cracking of yam tubers. Positive linear relationship was also observed between yam tuber weight loss and dry rot disease indicating that dry rot disease may have contributed to the tuber weight loss. Therefore, tuber dry rot symptoms caused by S. bradys of yams could be used to discard susceptible yams at harvest and after a period of storage. However, there was no linear relationship between nematode population densities in yam tubers and roots, therefore, a root protocol cannot be used for assessing resistance in yams as it could lead to misclassification. The yam germplasm screened, reaffirmed resistance to S. bradys in Dioscorea dumetorum var. Nkanfo and D. cayenensis var. Afun

Effect of Formaldehyde Treatment on Bacteria-Infected Hatching Eggs of Gallus gallus domesticus Linnaeus, 1758

The effectiveness of formaldehyde egg disinfection is well documented in literature despite its reported toxicity. This study focused on the need for an optimum formaldehyde concentration (FC) that significantly reduces microbial load with minimal damaging effect on egg viability and hatchability. Using a true experimental design, bacterial load on formaldehyde-treated (FT) and control groups of eggs and hatchability were compared. Gram-staining and biochemical tests identified five bacterial species: Escherichia coli, Enterobacter sp., Bacillus cereus, Staphylococcus aureus and Micrococcus sp. with the two coliform bacteria, E. coli and Enterobacter sp., dominating. Comparison of median differences of bacterial load on eggs before and after formaldehyde treatment by Wilcoxon Signed-Rank Test showed marginal significance in bacterial load reduction (Z = -2.016, P = 0.044). This difference was observed for bacterial load between the control group (CG) and the FT group with FC 30/20 ml/g (U = 3.0, P = 0.047). The hatchability of the CG differed significantly from four FT groups of eggs with FC 30/20 ml/g showing the highest level of significance [χ² (1) = 14.71; P = 0.0001]. A FC of 30/20 ml/g produced the best domestic fowl egg disinfection compared to other FCs and hatchability decreased with increasing formalin volume

Yaws

Introduction Yaws, caused by Treponema pallidum ssp. pertenue, is endemic in parts of West Africa, Southeast Asia and the Pacific. The WHO has launched a campaign based on mass treatment with azithromycin, to eradicate yaws by 2020. Sources of data We reviewed published data, surveillance data and data presented at yaws eradication meetings. Areas of agreement Azithromycin is now the preferred agent for treating yaws. Point-of-care tests have demonstrated their value in yaws. Areas of controversy There is limited data from 76 countries, which previously reported yaws. Different doses of azithromycin are used in community mass treatment for yaws and trachoma. Growing points Yaws eradication appears an achievable goal. The programme will require considerable support from partners across health and development sectors. Areas timely for developing research Studies to complete baseline mapping, integrate diagnostic tests into surveillance and assess the impact of community mass treatment with azithromycin are ongoin

Re-Evaluation of Yam Mosaic Virus (YMV) Detection Methods

Accurate and timely detection is vital for mitigation of tuber yield losses resulting from yam mosaic virus (YMV) infection on yam, a major food security crop in West Africa. The observation, from our previous studies, that the triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA), the most commonly used detection method for YMV, detected the virus in significantly less leaf samples than immunocapture reverse transcription polymerase chain reaction (IC-RT-PCR) necessitated a re-evaluation of YMV detection methods. In the present study, eighteen previously tested YMV positive leaf samples from Benin and Ghana were re-tested using TAS-ELISA, Protein A-sandwich (PAS) ELISA and IC-RT-PCR. Three sap dilutions, 1/10, 1/50 and 1/100, were tested for each sample. Both at 1/10 and 1/50 dilutions, PAS-ELISA and IC-RT-PCR detected YMV in 11 (61.1%) and 12 (66.7%) of the leaves respectively. Virus detection by PAS-ELISA reduced to 50% at 1/100 sap dilution and increased to 77.8% in IC-RT-PCR. YMV detection by TAS-ELISA varied between 38.9% and 16.7% at 1/10 and 1/100 dilutions respectively. These results indicate a deficiency in the use of TAS-ELISA as a sole YMV certification method since the detecting monoclonal antibody used in this assay may be strain specific. The use of PAS-ELISA at a 1/10 sap dilution is suggested for YMV detection where the facilities for molecular detection are unavailabl

Yaws.

INTRODUCTION: Yaws, caused by Treponema pallidum ssp. pertenue, is endemic in parts of West Africa, Southeast Asia and the Pacific. The WHO has launched a campaign based on mass treatment with azithromycin, to eradicate yaws by 2020. SOURCES OF DATA: We reviewed published data, surveillance data and data presented at yaws eradication meetings. AREAS OF AGREEMENT: Azithromycin is now the preferred agent for treating yaws. Point-of-care tests have demonstrated their value in yaws. AREAS OF CONTROVERSY: There is limited data from 76 countries, which previously reported yaws. Different doses of azithromycin are used in community mass treatment for yaws and trachoma. GROWING POINTS: Yaws eradication appears an achievable goal. The programme will require considerable support from partners across health and development sectors. AREAS TIMELY FOR DEVELOPING RESEARCH: Studies to complete baseline mapping, integrate diagnostic tests into surveillance and assess the impact of community mass treatment with azithromycin are ongoing