4 research outputs found

    Traditional African Vegetables Agrobiodiversity: Livelihood Utilization and Conservation in Tanzania Rural Communities

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    The agricultural sector is challenged to fulfill the nutritional requirements of ever-increasing population. Rates of growth in crop productivity have declined, among many reasons is due to climate change and the decline of water and land resources. Dependence by 50% on few cereal crops like wheat, maize and rice for total food intake and calorie requirements has countersigned loss of biodiversity and decline in crop productivity. The genetic diversity of traditional crop varieties offers resilience to environmental risks, socioeconomic shocks, adaptation and mitigation to climate change which is crucial for crop production. Traditional African Vegetables (TAVs) are an integral constituent of the diets of many rural and urban communities. They are important sources of essential macro and micro-nutrients. In addition, they offer a source of livelihood when marketed, and also contribute to crop biodiversity. Tanzania needs to conserve the Traditional African vegetables and their genetic resources against stressful conditions and increased selection pressures which causes loss of genetic variation and a decrease in fitness by a process called genetic erosion. Conservation and use alleviate genetic drift and inbreeding depression, then, is critical to guarantee TAVs persistence in rural areas. This review explores agrobiodiversity of traditional African vegetables (TAV) from livelihood of Tanzanian rural communities’ perspectives and how the country has managed to conserve these species

    Incorporation of resistance to angular leaf spot and bean common mosaic necrosis virus diseases into adapted common bean (Phaseolus vulgaris L.) genotype in Tanzania

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    Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes for ALS and BCMV/BCMNV diseases into adapted, market class and farmers and consumers preferred bean genotype using marker assisted selection. The parents Mexico 54 and UBR(25)95 donor of Phg-2 and I/bc-3 genes for ALS and BCMV/BCMNV, respectively were used for the recipient being Kablanketi. In selection, SCAR markers SNO2, ROC11 and SW13 linked to Phg-2, bc-3 and I gene, respectively were used. A parallel backcrossing (modified double cross) procedure was used. The F1, F2 and backcrosses from single crosses were characterized. The Chi square values for ALS were 0.081 (P<0.776) and 0.017 (P<0.896) and for BCMNV were 1.609 (P<0.205) and 1.2 (P<0.273) for molecular and phenotypic screening, respectively. The resistance to ALS and BCMNV was found to be monogenic and the genes involved are dominant and recessive, respectively. The heritability of ALS was found to be high (0.772) implying that selection for ALS can be done early in segregating populations. High correlation values, r = 0.741 and 0.624 for ALS and BCMNV, were obtained between phenotypic and molecular data, indicating high reliability for markers. In selection, it was possible to select lines with multiple disease resistances. This work signified the use of MAS for multiple gene screening.Keywords: Common bean, Pseudocercospora griseola, marker assisted selection, genotype, inheritanceAfrican Journal of Biotechnology Vol. 12(27), pp. 4343-435

    Genetic characterization of angular leaf spot resistance in selected common bean landraces from Tanzania

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    Angular leaf spot disease (ALS) caused by Pseudocercospora griseola is one of the most important bean diseases in Tanzania. The bean landraces Beti-10, Nanka, Nanavala and Nkanamna used in this study have been identified as resistant to ALS but the nature of inheritance and mechanisms of resistance against ALS in those potential sources has not been elucidated. This information is crucial and a necessary first step for a successful breeding programme. The objective of this work was to study the inheritance of ALS resistance in those landraces and to identify the mechanisms of genetic resistance using Simple Sequence Repeat (SSR) markers. Crosses were made between resistant bean landraces and a susceptible bean cv Kablanketi. The parents, F1, F2 and backcrosses derived plants were used for inheritance studies and for molecular marker screening using 30 SSR markers. Results indicate that, a single dominant gene control resistance against ALS in each of the four landraces; also the SSR marker Pv-ag004 was found to be polymorphic between Beti-10 and Kablanketi and linked to the disease resistance. The resistance were validated by checking the F2 population of the cross between Kablanketi Ă— Beti-10. Therefore, since marker Pv-ag004 is polymorphic and linked to ALS resistance, the Beti-10 landrace might be a potential source of ALS resistance. However, a detailed study with more markers need to be done on these landraces with a view to opening the possibilities of identifying new markers linked to ALS resistance and mapping of genes associated with resistance to ALS.Keywords: Phaseolus vulgaris, Inheritance, ALS, SSR, Pseudocercospora griseol
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