Abstracts 341 about the feasibility of eradicating the species following four years of continuum of specialisation and, therefore, promiscuous legumes control and monitoring. should have higher chances of forming effective symbioses in novel ranges. Using Australian Acacia species in South Africa we hypo- doi:10.1016/j.sajb.2017.01.076 thesised that widespread and highly invasive species will be more generalist in their rhizobial symbiotic requirements and more effective in fixing atmospheric nitrogen compared to localised and less invasive species. To test our hypotheses we used eight widespread and eleven localised acacias and utilized next generation fi Systematics and diversi cation of the genus Tephrosia and allies sequencing data for the nodulation gene, nodC, to compare the (Millettieae, Fabaceae) identity, species richness, diversity and compositional similarity of rhizobia associated with these acacias. We also used stable isotope a a b,c a R.M. Kabongo , H.E. Iheanacho , A.R. Magee , M. Van der Bank , analysis to determine levels of nitrogen obtained from the atmo- d J.S. Boatwright sphere via symbiotic nitrogen fixation. We found no differences in a African Centre for DNA Barcoding, University of Johannesburg, PO Box richness, diversity and community composition between localised 524, Auckland Park 2006, Johannesburg, South Africa and widespread acacias. Similarly, widespread and localised acacias b Compton Herbarium, South African National Biodiversity Institute, did not differ in their ability to fix atmospheric nitrogen. However, Private Bag X7, Claremont 7735, Cape Town, South Africa for some species by site comparisons we found significant differ- c Department of Botany and Plant Biotechnology, University of Johannesburg, ences in δ15N isotopic signatures, indicating differential symbiotic PO Box 524, Auckland Park 2006, Johannesburg, South Africa effectiveness between these. Overall, these results support recent d Department of Biodiversity and Conservation Biology, University of the findings that root nodule rhizobial diversity and community com- Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa position do not increase invasiveness in acacias. Differential inva- E-mail address: [email protected] (R.M. Kabongo) siveness of acacias in South Africa is likely linked to attributes like differences in their propagule pressure. Tephrosia Pers. is a large genus of legumes comprising some 350 species that are mostly African, but also extend to North and Central doi:10.1016/j.sajb.2017.01.078 America, Asia and Australia. Two subgenera are recognized within the genus, i.e. Tephrosia subg. Barbistyla Brummit and Tephrosia subg. Tephrosia. Relationships within the genus and among its close relatives in the Millettieae (Apurimacia Harms, Chadsia Bojer, Mundulea Benth., Pyranthus Du Puy & Labat, Ptycholobium Harms Evaluation of antimutagenicity effects of and Requienia DC., i.e. the Tephrosia-clade) are not well understood. Annona senegalensis fruit This study presents results of nuclear internal transcribed spacer (ITS) and plastid DNA sequence data (matK, rbcLa, ycf1) generated K.G. Kgosana, E.E. Elgorashi and analysed for the Tephrosia-clade, based on a representative Agricultural Research Council, Onderstepoort Veterinary Institute, Division sampling (236 taxa) of these genera across the world, and especially of Toxicology, Private Bag X05, Onderstepoort 0110, South Africa within Tephrosia. Preliminary results indicate that Tephrosia is E-mail address: [email protected] (K.G. Kgosana) polyphyletic, with Chadsia, Mundulea, Ptycholobium and Requienia embedded within. Apurimacia and Pyranthus are placed outside Annona senegalensis Pers., commonly known as African custard- of the main Tephrosia clade, although the support for this is weak apple, is a small flowering plant or shrub native to Western and in some analyses. In addition, Tephrosia subgenus Barbistyla is Southern Africa. It is a multipurpose plant which is traditionally used recovered as monophyletic in most analyses, while T. subgenus for food as it bears fruits for human consumption and leaves for Tephrosia is polyphyletic. These results and their implications for animal browsing to improve nutrition. It has a wide range of fi generic and infrageneric classi cation within the Tephrosia-clade medicinal properties ranging from anti-inflammatory, antimicrobial, will be discussed. anti-diarrhoeal, anti-parasitic, anticonvulsant, anti-malarial, anti- oxidant and anti-snake venom. Screening of more than 100 plant doi:10.1016/j.sajb.2017.01.077 extracts revealed that A. senegalensis has potential antimutagenicity effects against aflatoxin B1 and 4-nitroquinoline 1-oxide (4NQO). Hence 80% methanol extracts of A. senegalensis were subjected to a solvent-solvent fractionation process resulting in five fractions i.e., Legume-rhizobium symbiotic promiscuity and effectiveness do hexane, DCM, butanol, water and 35% water in methanol. All not affect plant invasiveness fractions were tested for antimutagenicity effects using an Ames assay with and without metabolic activations using Salmonella typhimurium TA100, TA98 and TA102 strains. Aflatoxin B1 and J.-H. Keeta, A.G. Ellisa, C. Huib,c, J.J. Le Rouxa,b 4NQO were used as standards in the Ames assay with and without aDepartment of Botany and Zoology, Stellenbosch University, Matieland metabolic activation, respectively. All tested fractions were evaluated 7602, South Africa and their antimutagenicity effects classified as weak, moderate and bCentre for Invasion Biology, Department of Mathematical Sciences, strong when the percentage of inhibition obtained was b25%, 25-40% Stellenbosch University, Matieland 7602, South Africa and N40%, respectively. The hexane fraction was the most promising cMathematical and Physical Biosciences, African Institute for Mathematical and therefore, selected for continuation with bioassay guided Sciences, Cape Town 7945, South Africa fractionation so as to isolate the bioactive compounds. The isolated E-mail address: [email protected] (J.-H. Keet) bioactive compounds will be characterised by NMR and MS in order * Awarded prize for best PhD presentation to elucidate their structures.

The ability to fix atmospheric nitrogen is thought to play an important role in the invasion success of legumes. Interactions doi:10.1016/j.sajb.2017.01.079 between legumes and nitrogen fixing bacteria (rhizobia) span a