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    Variation in growth, nutrition and phytochemicals of sequentially harvested shoots and fruits, and genetic studies of Lagenaria siceraria landraces in South Africa
    (University of Zululand, 2024) Buthelezi, Lungelo Given; Ntuli, N.R. Mavengahama, S. and Sibiya, J.
    Lagenaria siceraria (Molina) Standley, a member of the Cucurbitaceae family, is valued for its many uses, serving as a crucial food source with edible plant parts such as leaves, shoots, fruit pulp, and seeds. However, studies on L. siceraria regarding the relationship between shoot, peduncle and fruit traits during growth; nutritional and phytochemical composition of sequentially harvested shoots and fruits; as well as genetic diversity among landraces using single nucleotide polymorphism (SNP) markers, are limited. These studies are crucial for enhancing plant physiological understanding, optimizing crop yields, improving nutritional value, and preserving genetic diversity in L. siceraria. Therefore, the objectives of this study were to correlate shoot, peduncle, and fruits’ traits during growth; compare the nutritional composition of shoots and fruits, and phytochemical profile of fruits harvested at different maturity stages; and assess the genetic variability using SNP markers in L. siceraria landraces sourced from northern KwaZulu-Natal and Limpopo, South Africa. Multivariate analyses were conducted along with the estimations of heritability. Harvested shoot, peduncle, and fruit traits showed significant variation (p < 0.05) within each growth period and at different growth stages. Peduncles of all landraces became shorter and thicker when fruits were elongating and widening, from 0–5 days after anthesis (DAA). Positive correlations were notable among all shoot traits (shoot length, shoot width, shoot fresh mass, shoot dry mass, and shoot moisture content), and peduncle width correlating with fruit length and width. The first three principal components explained 85% of the total variability. Clustering identified three main groups, with singlets for landraces KRI and NSRC. Landraces were clustered according to peduncle and fruit sizes, as well as availability of harvestable shoots. High heritability estimates were recorded for peduncle length (55.2%) and shoot width (60.2%). Differences in nutrient attributes were significant within and among landraces where shoots and fruits were harvested at various growth stages. Nutritional traits correlated either positively or negatively with each other based on their translocation modes and similar chemical properties. The first five principal components explained 90.218% and 89.918% total variability in shoots and fruits, respectively. Micronutrients Ca, Mg, K, P, and N in shoots and macronutrients Fe, Zn, Cu, and Al in fruits, were the primary contributors of variability. Shoot nutrient content associated landraces into three major clusters, based on landraces with superior and inferior levels of specific nutrients at different growth stages, as well as those with distinctive nutrient profiles. Fruit nutrient status also grouped landraces into two major clusters, reflecting variations in nutrient content at different growth stages. Phytochemical analysis identified five isoprenoids in fruits harvested at 7 DAA across all landraces, namely 1-Dodecene, 2,3-Dimethyldodecane, E-15-Heptadecenal, Eicosane, and Tridecane, 6-propyl. Lighter metabolites in molecular mass displayed shorter retention rates (9.08-16.29 min) with lower relative peak areas (1.09-6.97%), while heavier compounds exhibited longer retention rates (13.42-18.00 mins) with higher relative peak areas (2.25-11.41%). Landraces were grouped into five clusters based on fruit and seed attributes and significant isoprenoid units. Terpenoids were the predominant phytochemicals commonly identified among landraces’ fruits at different stages of growth, where 1-Dodecene; Decane,3,7-dimethyl-; 1-Octadecane; 1-Pentadecene; E-14-Hexadecenal; E-15-Heptadecenal; Eicosane; Tetradecane, 4-methyl; and Tridecane, 6-propyl-, were the highest contributors to variation. Correlation in phytochemicals was predominantly based on their availability at different fruit growth stages. Three distinct clusters grouped landraces according to the unique presence of phytochemicals at different stages of growth, as well as landraces with similar fruit traits and phytochemical availability at different growth stages. Genetic variation at a single nucleotide base was identified among studied landraces, where the sequencing of 16 landraces revealed variations in the target genes ACS27 and CmFIS8. Molecular variance analysis and phylogenetic tree construction indicated variations among landraces. Sequenced landraces showed an average of 1.75 alleles, effective alleles at 0.419, Shannon’s information index at 0.403, expected heterozygosity at 0.265, gene flow at 6.80, and genetic differentiation at 0.082. Sequence variations were observed, and landraces were clustered based on genetic differences. Analysis of Molecular Variance (AMOVA) indicated 100% variation among landraces of different origins.
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    Indigenous knowledge, variation in morphology, nutritional composition and genetics of Strychnos spinosa morphotypes
    (2023) Mbhele, Zoliswa
    Strychnos spinosa Lam., commonly known as green monkey orange (English) and umHlala (isiZulu), belongs to the Loganiaceae family. It is of African origin, and in South Africa it grows predominantly in the Eastern Cape, Limpopo, KwaZulu-Natal, and Mpumalanga provinces. It is used for food, medicine and to improve the socio-economic status of rural communities. However, studies on indigenous knowledge, variation in morphology, nutritional composition, and genetics among S. spinosa morphotypes are limited. Thus, this study aimed to determine the indigenous knowledge, variation in morphology, nutrition, and genetics among S. spinosa morphotypes. Local indigenous knowledge on S. spinosa was documented from Oyemeni community in KwaZulu Natal, whereas variation in morphology, nutritional and genetic analysis were assesed from morphotypes at Bonamanzi Game Reserve in Northern KwaZulu-Natal. Indigenous uses of S. spinosa included direct fruit consumption; development of local and nutrient dense food products and drinks, such as fermented maize meal (umBhantshi), fermented porridge (amaHewu), alcohol, juice, and jam; various medicines; as well as for homestead protection, livestock increase and firewood. Oyemeni community gave the first report on umBhantshi preparation from S. spinosa, and indigenous knowledge on the morphological and organoleptic variations that exist within S. spinosa. Apparently, the whole study was the first evidence of variation among S. spinosa morphotypes based on morphological, nutritional, and genetic traits. This also included the first report on the existence of purple, pyriform, and rough fruits, as well as a purple tint on the juvenile leaves. Fruit and seed traits, as well as calcium, phosphorus, magnesium, copper, iron, manganese, fat, acid detergent fibre, neutral detergent fibre, sodium and crude protein nutrient, were the important traits used to determine variation among S. spinosa morphotypes, based on principal component analysis. In cluster analyses, morphotypes GRR-dGEO, GRxCP-GEF, GvRxCR-GEF, GRxCP-dGEF, PRR-dGRF, PRxCP-GEO, GvRR-dGEO, GvRR-GRO, GRxCR-dGEF, and GRxCR-dGEO were associated based on their rough pericarp texture, small-sized fruits, high nutrient content in fruits, and related genetic attributes. These morphotypes can be recommended for future breeding, domestication, use in various food products and commercialisation practices. This study also reported the first development and successful use of simple sequence repeat markers for genetic diversity and population structure of S. spinosa. Results on diversity in morphology and genetics of S. spinosa morphotypes can be used to improve these fruit species for commercialisation and enhanced food security, as they have a nutritional profile that is above well-known commericial fruits.
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    Comparative assessment of agro-morphological traits and nutrient content of Sesamum alatum in response to poultry and goat manures
    (2021) Mbatha, Khulekani Cyprian
    Sesamum alatum Thonn. is one of the scarcely known and highly nutritious leafy vegetables that is still collected from the wild or as weeds among crops in South Africa. The plant is also used for medicinal and cosmetic purposes in Africa and elsewhere. Despite its importance and agronomic potential, the cultivation of S. alatum under different agronomic systems for improved harvestable yield and nutrient content is still lacking. The study aimed to determine the response of S. alatum agro-morphological traits and nutrient content to the application of poultry and goat manures. This study was conducted under rain-fed shade cloth conditions during the summer months of 2018 and 2019. Pots (20L) were filled with 60 kg of soil mixed with poultry and goat manures at 0, 1, 2, and 3 t ha–1 each. The layout was a completely randomized design (CRD) of 2 × 4 factorial combinations. Taller plants with numerous branches that produced many and bigger leaves and heavier shoots were recorded in season two. The application of manure resulted in taller plants with profuse branching, many, and broader leaves as well as heavier dried shoots. However, goat manure was more effective than poultry manure. The recommended rates for optimum plant agro morphological productivity were ≥ 2 t ha–1 for both manures except for the seed mass. Application rates ≥ 2 t ha–1 of goat manure gave the best vegetative and reproductive growth in S. alatum. Poultry and goat manure application led to an increase in moisture content, Ca, Mg, K, P, and micronutrients in Sesamum alatum. Goat manure produced the highest nutrient content of S. alatum than poultry manure, although differences were not substantial. Therefore, both manures could be equally used to improve agro morphological traits and nutrient content of S. alatum.
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    Morpho-agronomic and genetic variation and segregation patterns of phaseolus vulgaris landraces from selected provinces of South Africa
    (University of Zululand, 2021) Ndlangamandla, Valencia Vuyisile
    Phaseolus vulgaris L. (dry beans) of Central American origin is a self-pollinating crop with a low frequency of crossing. It is planted for its edible leaves, immature pods, and dried seeds throughout the world. In South Africa, local communities grow a variety of P. vulgaris landraces. Landraces are significant for breeding purposes because they contain important germplasm. However, studies on variation in morphology and genetics among P. vulgaris landraces are limited in South Africa. Thus, this study aimed to determine the morpho-agronomic and genetic variations among P. vulgaris landraces. P. vulgaris landraces collected from the various rural communities of four selected provinces in South Africa were grown in a randomized complete block design with three replications over two seasons. Significant variations were recorded in germination percentages, vegetative and reproductive traits. The vegetative and reproductive traits correlated positively with each other, and with both traits. The first five informative principal components explained 88.749% and 91.678% of the total variation in the morpho-agronomic and segregation patterns, respectively. The landraces were clustered in a biplot and dendrogram based on their seed coats, shape, similar morpho-agronomic traits, and their area of origin. The 12 parents of P. vulgaris produced offspring that are different from their parents in seed colour, shape, and size. The genetic diversity analysis with simple sequence repeat (SSR) markers revealed the range of genetic diversity, observed heterozygosity, and polymorphic information content as 0.00–0.65, 0.00–0.05, and 0.00–0.58, respectively. The population structure divided the 40 landraces into two subpopulations namely Mesoamerican and Andean gene pools. Although there was considerable overlap among the landraces, numerous Mesoamerican landraces carried certain seed features or genes from the Andean gene pool, indicating a significant amount of mixing. Although, the populations showed an overlap among the landraces as several from the Mesoamerican group carried some seed traits or genes from the Andean gene pool, as they showed a high level of admixture. The grouping of landraces in a principal coordinate analysis (PCoA) and dendrogram had a similar clustering to the population structure. The landraces demonstrating admixture were also grouped in the same cluster (dendrogram) and similar quadrants (PCoA). The findings of the variance in morpho-agronomic and genetics of P. vulgaris landraces can be used to improve, conserve them, and increase their productivity.
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    A Toxicological Evaluation and Anti-Candidal Activity of Plants used by Women in Northern Maputaland (South Africa) for the Treatment of Gynaecology and Obstretrics Ailments
    (University of Zululand, 2021) Ngubane, Samukelisiwe Clerance
    Medicinal plants still play an important role in the primary healthcare of lay people in northern Maputaland in spite of the availability of hospitals and clinics. According to an ethnobotanical survey conducted in 2014, the lay people in northern Maputaland use plant species independently and in combination to treat gynaecology and obstetrics medical conditions. These plant species were generally regarded as safe by the lay people except for one plant species, Trichilia dregeana. Consequently, this study’s aim was to investigate the safety of medicinal plant species used by the lay people in northern Maputaland. Furthermore, as these plant species were used to treat medical conditions specifically related to woman, the inclusion of the efficacy of these plant species against Candida stains was included due to the prevalence of vaginal thrush. The aqueous and organic (1:1 methanol-dichloromethane) extracts were prepared from 51 plant samples (including leaf samples collected for potential substitution for the roots). Toxicology of these plants was assessed using the brine shrimp lethality assay (BSLA) and the Ames assay (using Salmonella typhimurium TA98 and TA100 strains) for mutagenicity. The anti-Candidal activity was assessed using the antimicrobial micro-dilution assay to determine the minimum inhibitory concentration of of the plant samples aginst Candida albicans ATCC 10231, C. tropicalis ATCC 750 and C. glabrata ATCC 900300. There were three plant spescies (Acalypha villicaulis root, Grewia occidentalis root and Gymnosporia senegalensis leaves) that indicated neither toxicity nor mutagenicity in this study. All the toxic plants samples (in BSLA) were further subjected to two-fold dilution and demonstrated acceptable toxic concentrations, which were found to range from 0.98 to 0.10 mg/ml. However, Hermannia boraginiflora, Sapium integerrimum, Scadoxus puniceus and Tabernaemontana elegans remained toxic even after diluted to the lowest concentration of 0.031 mg/ml. Plant species combinations that were found to be non-toxic in BSLA in both aqueous and organic extract were Euphobia tirucalli (root) + Ozoroa engleri (bark) + Scadoxus puniceus (bulb) + Senecio serratuloides (whole plant), Bridelia cathartica (root) + iii Opuntia stricta (stem) + Searsia nebulosa (bark) and B. cathartica (root) + Erythrina humeana (root). In the Ames test, plant samples that appeared to be non-mutagenic against both S. typhimurium TA98 and TA100 strains were A. villicaulis root, Cyperus natalensis root, Euclea natalensis leaves, G. occidentalis root, Ochna natalitia leaves, S. integerrimum leaves and S. puniceus bulb. However, Hypoxis hemerocallidea and O. stricta appeared to be the most mutagenic against both the S. typhimurium TA98 and TA100 strains with both aqueous and organic extracts showing mutagenicity. The antimicrobial microdilution assay indicated a small number of plant species that were active against Candida strains and were in most cases these were the methanoldichloromethane extracts. A moderate activity against C. albicans was observed with the aqueous extract of Euclea natalensis root and Rhoicissus digitata leaves. The methanol-dichloromethane extracs of O. stricta stem, P. africanum root and S. birrea stem were also active (moderately) against C. albicans. Against the C. tropicalis, a moderate activity was observed against A. villicaulis leaves, Acanthospermum glabratum whole plants, B. cathartica leaves, Cassytha filiformis whole plant, Euphorbia tirucalli stem and Garcinia livingstonei root. A noteworthy anti-Candidal activity was observed with Commiphora neglecta root and leaves both with the minimum inhibitory concentration (MIC) of 0.13 mg/ml against Candida tropicalis. There was no activity observed against C. glabrata. This study has indicated that medicinal plant species may have toxic and/ or mutagenic effects, even without any noteworthy signs after consumption. However, it was determined that toxicity can be reduced by carefully managing the dose. The reduction of concentration is not known whether it may affect the efficacy, therefore further studies on the efficacy are recommended.
University of Zululand