Characterisation and control of Curvularia lunata infecting farmer-saved rice seeds in Ghana

Curvularia species are increasingly important seed-borne fungi, whose identification has been done based solely on cultural and morphological features in Ghana. To confirm the identity of the fungus in Ghana, isolates of the fungus obtained from farmer-saved rice seeds were identified using cultural and morphological features, complemented with phylogenetic analysis of the internal transcribed spacer regions of isolates. The susceptibility of isolates to three plant based fungicides, Levo, Kobe and Ex-icute was determined with in-vitro and in-vivo. All isolates produced curved shaped spores with several septations. In the phylogram, they all clustered in the C. lunata clade, confirming their C. lunata species status. All isolates were susceptible to the three organic fungicides and seeds treated with the three fungicides reduced fungal infection percentage. For safer environmental practices, these plant based fungicides are recommended for rice seed treatment

Mycofloral Diversity and Molecular Characterization of Species Isolated from Farmer-Saved Rice Seeds in the Irrigated Rice Production Districts of the Coastal Savannah Zones of Ghana

Irrigated rice production is the major type of rice production in the Coastal Savannah Zone of Ghana, where farmers rely on their saved seeds for production. A study was carried out to determine the types of storage fungi resident on farmer saved seeds and their distribution in five major rice production areas of the Coastal Savannah Zone. The blotter method was used to isolate fungal species after which they were identified using cultural and morphological features complemented by sequence analysis of the entire Internal Transcribed Spacer (18S-ITS1-5.8S-ITS2) region of isolates. Eleven fungal species namely, Alternaria alternata, Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Colletotrichum gloeosporioides, Curvularia lunata, Curvularia geniculata, Fusarium equiseti, Lasiodiplodia theobromae, Rhizopus oryzae and Trichoderma sp. belonging to 8 different genera were isolated and identified on the rice seeds. Curvularia lunata, with a percentage occurrence of 63.9% was the most prevalent fungal species, while Trichoderma sp. (1.3%) was the least prevalent fungal species from the study area. The high infection rate of seeds by Curvularia species may lead to high incidence and severity of Curvularia leaf spot disease in the study area. &nbsp

Differential Activity of Caspase-3 Regulates Susceptibility of Lung and Breast Tumor Cell Lines to Paclitaxel

Recent development of tumor resistance to paclitaxel presents a major problem to cancer treatment. An unsettled controversy in the cancer chemotherapy field, however, is whether caspases play a prominent role in paclitaxel-induced death in tumors. Previous studies suggest that cleavage of caspase-3 is not instrumental for the execution of death in tumors treated with paclitaxel, while other reports indicate that caspase-dependent pathways may be critical for paclitaxel cytotoxicity. In this study, we investigated the role of caspase-3 in breast and lung tumor cell line sensitivity to paclitaxel. Clonogenic survival and live/dead viability-assays, together with enzymatic activity and cell proliferation assays, reveal that the levels of paclitaxel-induced caspase-3 enzymatic activity in tumor cells correlate directly with tumor sensitivity to the drug.We observed a 2-fold increase in caspase-3 activity in 4T1-Luc breast tumor cells, but a 3-fold and 4-fold decrease in A549 and A427 lung tumor cell lines, respectively. Together, our results suggest that caspase-activation and activity levels are not only key determinants of paclitaxel-induced death in tumors but also serve as good indicators for tumor susceptibility to paclitaxel therapy. Our studies also indicate that within clinically relevant doses of paclitaxel, the ability to rid tumor populations of dormant tumor cells controls the rate of tumor recurrence

Phenotypic screening of cowpea (Vigna unguiculata (L.) Walp) genotypes for resistance to cowpea viral diseases

Viruses are a major constraint to cowpea production in sub-Saharan Africa. Host plant resistance is the most effective and reliable method of managing viral diseases. In order to identify the source of resistance or tolerance, 38 cowpea genotypes were screened for virus infection under field conditions during the 2016 wet and dry seasons. The experiment was laid out in a randomized complete block design with four replications in both seasons. Disease severity was assessed fortnightly based on disease symptom using 1-5 visual scale (1=symptomless, and 5= very severe symptom). The cowpea genotypes exhibited varying reactions to viral infections with mean disease incidence ranging from 17.7% in the fourth week to 29.2% in the eighth week for the wet season and from 34.4% to 53.1% for the fourth and eighth week, respectively in the dry season. Symptoms observed were leaf mosaic (86.7%), leaf mottling (86.7%), chlorotic spots (34.2%), vein clearing (28.9%), leaf curl (26.3%), necrotic lesions (15.8%) and stunting (10.5%). Symptom severity in the rainy season ranged from symptomless (severity score of 1) in IT10K-819-4 and IT07K-297-13 to moderate symptom (severity score of 2.9) in Apagbaala. However, in the dry season, the symptom severity score ranged from 1.11 (mild symptom) in Marfo Tuya to a score of 2.4 (moderate symptom) in IT07K-298-9, thus demonstrating a significant genotype x season interaction effect. Incidence and severity were significantly higher in the dry season than in the rainy season. There was a strong positive correlation between the disease incidence and disease severity as well as AUDPC and no correlation between the cowpea incidence and the seed yield and plant height in the wet season. There was a negative correlation between the incidence and plant height in the dry season. Six genotypes (IT07-210-1-1, IT07K-297-13, IT08K-193- 14, IT09-456, IT10K-817-3 and IT10K-819-4) exhibited mild symptoms and gave high yields in both seasons, thus demonstrating a stable G x E interaction effect. These disease resistant genotypes could be evaluated further before release to farmers.Keywords: Area Under Disease Progress Curve, Host resistance, Vigna unguiculata, Viral disease

Biochemical Characterisation of 18 Accessions of Sweet Potato (Ipomoea batatas L. Lam.) using Total Leaf and Tuberous Root Protein by SDS-PAGE

DNA-based markers,undeniably, provide potent tools for studying genetic relationships in plants; however, potential of protein-based markers using SDS-PAGE is quite promising, particularly in developing countries. Plant storage proteins serve as molecular reserves imperative for plant growth and maintenance and thus have proven to be essential for the survival of plant species. Storage proteins are also indispensable in plant defense mechanisms as insecticidal and anti-microbial proteins. They have also been widely employed as biochemical markers for genetic diversity studies. Eighteen sweet potato (Ipomoea batatas L. Lam) accessions with local or exotic origin were evaluated for genetic diversity using leaf and tuberous root protein via sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Marked variations observed in the electrophoregrams of total leaf and tuberous root proteins gave an indication of intense variability among the accessions. Molecular size of proteins ranged from 20.23 to 28.89 kDa and 22.44 to 97.19 kDa, in the total leaf and tuberous root proteins, respectively. Two pairs of accessions SA/BNARI and UE 007 as well as HMA 1 and US 029 were identified as duplicates based on their banding patterns. Keywords: Biochemical, characterisation, SDS-PAGE, sweet potato, leaf& tuberous root protei

Performance of rice under different water regimes and plant nutrient sources

Field experiment was carried out at the Soil and Irrigation Research Centre, University of Ghana, Kpong in 2015 and 2016 cropping seasons to evaluate the effect of different soil water condition and plant nutrient sources on the growth and yield of rice. The experiment was laid out in a split plot design with three replications. Water regime and nutrient source were the main and sub-plot factors, respectively. Water regimes included; continuous flooding (CS), alternate wetting and drying (AWD) and moist soil condition between field capacity and permanent wilting point (MC) while the nutrient fertilizer treatments included no fertilizer (N0), 90 kg N/ha mainly from urea fertilizer (N1), 90 kg N/ha from 12.8 tons of compost (N2) and 45 kg N/ha from urea fertilizer + 45 kg N/ha from 6.4 tons of compost (N3). Results from the study revealed that keeping the soil periodically in aerobic and anaerobic condition through AWD method of water management recorded similar growth and grain yield of rice as with complete submergence of paddy field. Combination of inorganic fertilizer and compost for each to supply 45 kg N/ha under AWD produced the highest rice growth and grain yield. There was a positive and significant correlation between grain yield and growth parameters (plant height, chlorophyll content and above ground biomass accumulation).

INVESTIGATION OF NOISE EXPOSURES, PERCEPTION, AND HEALTH EFFECTS IN DIFFERENT MICROENVIRONMENTS IN A UNIVERSITY COMMUNITY

This study aims to assess noise levels in selected outdoor and indoor microenvironments in a University community in Oman. The perception of noise levels within the Sultan Qaboos University campus was investigated through a survey study. Also, the effect of exposed noise levels on annoyance and sleep disturbance were predicted including their potential risk on cardiovascular health. Among all the measured parameters, it was found that outdoor (41.6%-50%) and indoor (38.5%-46.2%) microenvironments have exceeded the critical levels of 55 dB during morning and afternoon periods. The respondents (698 people) identified traffic and indoor building-related activities as the main sources of noise levels but the majority (44%) of them rated their impact as low. However, more than 30% of the respondents considered traffic as the main contributor to University noise levels. The percentage of highly annoyed persons was predicted to be high in outdoor areas especially in the residential (25%) and near the hospital (13%) areas. However, indoor environments including construction materials and structures labs (14%) showed similar annoyance rates. Also, the percentage of high sleep disturbed persons was found higher in residential areas (7.4%) areas compared to hospital areas (5.3%) locations. The study concluded that there might be an association between the exposed noise levels and the risk of developing cardiovascular diseases. This is the first study that has provided a high spatial variability noise exposure levels across a University environment in Oman, this will contribute to designing future sustainable mitigation strategies to improve the health and well-being of the exposed population. The study has provided a baseline knowledge needed for future epidemiological studies

Study of the Reproductive Characteristics of Nine Cassava Accessions

Reproductive behaviour of two cultivars (AF and AN) and seven breeding lines (BA, AS, LA, BS-1, HO-008, ME and SE) of cassava (Manihot esculenta Crantz) was studied to obtain information pertaining to flowering habits and other reproductive characteristics of these potential parents required for future hybridization programmes. The accessions were grown on the Research Farm of the Biotechnology and Nuclear Agriculture Research Institute in the coastal savanna agro-ecological zone of Ghana between April 2008 and December 2009. For each accession, 40 stem cuttings, each bearing five to eight nodes, were prepared from the mid-section of healthy cassava stems and planted at a spacing of 1.5 m x 1.0 m while accessions were separated by a distance of 2 m. Ten plants were tagged per accession for the collection of data on key reproductive characteristics. All accessions flowered, suggesting that flower production may not be a limiting factor under the prevailing climatic conditions. Light microscopy revealed that one accession (BA) produced dysfunctional male flowers which were devoid of pollen. Mean days to flowering and fruiting varied significantly (P < 0.05) among the accessions, indicating the need to use different planting dates for different accessions to ensure synchronization of flowering. The accessions also differed significantly (P < 0.05) with respect to plant height at various levels of branching, as well as number of inflorescences, staminate and pistillate flowers, and fruit produced per branching level. There was also variation in percent seed set, embryo formation and fruit drop. The extensive variability observed among the accessions provides breeders with immense opportunities for carrying out cross combinations to generate new genotypes to meet specific objectives

Agromorphological Characterisation of 29 Accessions of Okra (Abelmoschus spp L.)

The West African sub-region is indisputably the region of greatest diversity of Okra (Abelmoschus spp L.) germplasm as it currently hosts some 1,769 accessions of Okra (representing 77.49%) out of the 2, 283 reported world-wide. These are largely uncharacterised, making it practically impossible to ascribe specific attributes to known accessions to facilitate breeding for further improvement to meet specific demands by end-users or industrial-scale production. Twenty six (26) local accessions and three (3) exotic lines of Okra were collected from eight geographic regions of Ghana. Their agro-morphological traits were evaluated under field conditions on the research farm of the Biotechnology and Nuclear Agriculture Research Institute. Hierarchical cluster analysis of results grouped the accessions into two major clusters and subsequently into five sub-clusters based on the qualitative characters studied. The pattern of clustering did not indicate any relationship with geographic origin of collection. The two most divergent accessions were Cs-Legon (local accession) and Clemson spineless (exotic line). There were no duplicates among the accessions which exhibited great variability with respect to all vegetative as well as reproductive characters, except one. Keywords: Okra; accession; characterisation; phenotypic variation; cluster analysis; genetic similarity index