Morphology and genetic relationships in members of the Solanum nigrum L. complex used for jam production in the Highveld of South Africa
The family Solanaceae consists of many important crop species such as tomatoes, potatoes and peppers. The Solanum nigrum complex (black nightshades) also form part of this family and are an emerging, important food source in parts of Africa. Both leaves and ripe fruits are consumed. Additional adv...
Summary: | The family Solanaceae consists of many important crop species such as tomatoes, potatoes and peppers.
The Solanum nigrum complex (black nightshades) also form part of this family and are an emerging,
important food source in parts of Africa. Both leaves and ripe fruits are consumed. Additional advantages
of the nightshades include several medicinal properties, high nutritional value and natural resistance
mechanisms against many disease causing pathogens of the Solanaceae. The objectives of this study were
to compare accessions used for “nastergal” jam production in the Highveld of South Africa to reference
species of the S. nigrum complex using (i) morphological (ii) ploidy and (iii) molecular information.
Twenty-nine morphological traits separated the farm-collected samples into three distinct groups. Flow
cytometry indicated the presence of a polyploidy series (diploid, tetraploid and hexaploid entities), and
the presence of possible hybridization events within the complex. ITS rRNA and three chloroplast genes
(matK, ndhF and rbcL) were sequenced for phylogenetic analysis. ITS yielded 19 informative sites across
600bp, while only six informative sites were identified across 3600bp of chloroplast gene sequences.
Chloroplast genes yielded few phylogenetically informative sites, and were not able to distinguish
between nightshade accessions. Diversity array technology, a whole genome genotyping approach on
microarrays, produced 1145 polymorphic markers between the accessions. ITS rRNA gene sequencing
and DArT data produced similar results, with three main groups distinguished, supported by
morphological data. Our data suggests that farmers are using fruits of Solanum retroflexum, Solanum
chenopodioides and Solanum americanum for jam production. Future work includes measuring levels of
vitamin C, proteins, sugars and anthocyanins in the berries, as well as solanine content to shed light on
assumptions concerning the toxicity of unripe berries. The results obtained could aid in the identification
of germplasm which would be suitable to initiate breeding programs for enhanced physiological or
metabolic traits for high quality jam production. === Dissertation (MSc)--University of Pretoria, 2011. === Plant Science === Unrestricted |
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