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Diversity of landraces and wild forms of watermelon (Citrullus lanatus)

distribution and implications for conservation in southern Africa, with emphasis on Zimbabwe

Mujaju, Claid (2011). Diversity of landraces and wild forms of watermelon (Citrullus lanatus). Diss. (sammanfattning/summary) Alnarp, Sweden : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2011:93
ISBN 978-91-576-7637-5
[Doctoral thesis]

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Abstract

Watermelon (Citrullus lanatus) is commonly grown in traditional agrosystems throughout the drought-prone Southern Africa as a staple food (edible seeds), a dessert food (edible flesh), and for animal feed. Several morphotypes of watermelon are found in this area; sweet watermelon, cooking melon and seed melon landraces of the traditional agrosystems; and possibly introgressed types which are regarded as agronomic weeds. There has been little work on investigating the relationships between wild and cultivated forms, and to study amount and partitioning of genetic variation, to allow for better conservation strategies. Previous studies have reported relatively low levels of genetic diversity in cultivated watermelon but these have been based mainly on US plant introductions and modern watermelon cultivars linked to breeding programmes for disease resistance. By contrast, germplasm maintained in the putative centre of origin in southern Africa, can be expected to display considerably higher variability.
Three different sampling strategies were used to collect plant material of both wild and cultivated forms of cow-melons (Citrullus lanatus var. citroides) and of sweet watermelons (C. lanatus var. lanatus, only known from cultivation); (1) in-depth sampling in the fields of one village in Zimbabwe, (2) medium-scale sampling across the watermelon growing districts in Zimbabwe, and (3) broad-scale sampling across Southern Africa (Botswana, Namibia, South Africa, Zambia and Zimbabwe). Two molecular marker methods were used, random amplified polymorphic DNA (RAPD) and simple sequence repeats (SSR) also known as microsatellite DNA. Similarity matrices obtained with RAPD and SSR, respectively, have been highly correlated, suggesting that for some applications, the less demanding RAPD can be a useful alternative, especially in developing countries. Considerable amounts of genetic diversity were found at all levels, including within-accessions (half-sib families). Sweet watermelon accessions appear to contain almost as much variability as cow-melon accessions. A genetic structure analysis divided the wild-weed-landrace complex collected in one village into three groups confirming the existence of three major forms with limited admixture. Defining the major forms into landraces and/or folk varieties was considered critical for identification of proper units for both on-farm and ex-situ conservation. Distribution of most watermelon accessions in Zimbabwe was associated with sandy loam and sand soils.

Authors/Creators:Mujaju, Claid
Title:Diversity of landraces and wild forms of watermelon (Citrullus lanatus)
Subtitle:distribution and implications for conservation in southern Africa, with emphasis on Zimbabwe
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :24 October 2011
Volume:2011:93
Number of Pages:53
Papers/manuscripts:
NumberReferences
IMujaju C., Sehic J., Werlemark G., Garkava-Gustavsson L., Faith M. & Nybom H. 2010. Genetic diversity in watermelon (Citrullus lanatus) landraces from Zimbabwe revealed by RAPD and SSR markers. Hereditas 147, 142-153
IIMujaju C., Zobrowska A., Werlemark G., Garkava-Gustavsson L., Andersson S.B. & Nybom H. 2011. Genetic diversity among and within watermelon (Citrullus lanatus)landraces in South Afrika. Journal of Horticultural Science & Biotechnology 86, 353-358.
IIIMujaju C. 2011. Distribution patterns of watermelon forms in Zimbabwe using DIVA-GIS. International for Biodiversity and Conservation. 3, 474-481
IVMujaju C. & Nybom H. 2011. Local-level assessment of watermelon genetic diversity in a village in Masvingo Province, Zimbabwe: structure and dynamics of landraces onfarm. African Journal of Agricultural Research (Accepted).
Vujaju C., Werlemark G., Garkava-Gustavsson L., Smulders M.J. & Nybom H. 2011. The dynamics of genetic diversity and farmers' use of a ild-weed-landrace complex ofwatermelon in Zimbabwe (Manuscript).
VIMujaju C. & Sehic J. 2011. Assessment of EST-SSR markers for evaluating genetic diversity in watermelon accessions from Zimbabwe (Manuscript).
Place of Publication:Alnarp, Sweden
Publisher:Dept. of Plant Breeding and Biotechnology
Associated Programs and Other Stakeholders:SLU/LTJ - Partnership Alnarp
ISBN for printed version:978-91-576-7637-5
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
Subjects:Obsolete subject words > FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING > Plant production > Plant breeding
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Agricultural Science
Obsolete subject words > NATURAL SCIENCES > Biology > Cell and molecular biology > Genetics
Agrovoc terms:citrullus lanatus, water melons, wild plants, cultivated plants, land varieties, genetic variation, rapd, micraosatellites, zimbabwe, southern africa
Keywords:Citrullus lanatus, genetic diversity, RAPD, SSR, folk variety, landrace, cow-melon, sweet watermelon
URN:NBN:urn:nbn:se:slu:epsilon-e-246
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-246
ID Code:8399
Department:(LTJ, LTV) > Plant Breeding and Biotechnology (until 121231)
External funders:Nordic Council of Ministers
Deposited By: Claid Mujaju
Deposited On:02 Nov 2011 13:34
Metadata Last Modified:02 Dec 2014 10:47

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