Systematics of the genus Tribulus (Zygophyllaceae) in southern Africa

Systematics of the genus Tribulus (Zygophyllaceae) in southern Africa

Abstracts Nitrogen (N) constitute one of the major plant nutritional components influencing plant growth and development patterns. In response to vari...

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Nitrogen (N) constitute one of the major plant nutritional components influencing plant growth and development patterns. In response to variations in nutritional composition of the growth medium, plants often adjust their metabolism and progressively alter their growth patterns. In examining the field growth dynamics and physiological parameters of in vitro regenerated Cyrtanthus guthrieae to different ratios of NH4:NO3, significantly different relative growth rates were recorded. A strong positive correlation between leaf area and growth rate was observed among the different nitrogen treatments. A significant difference in leaf area was recorded between the least leaf area (24.4 cm2) from a 0:1 NH4:NO3 ratio and the highest leaf area (115.1 cm2) from a 1:1 NH4:NO3 ratio. Although the relative electron transport rate (rETR) of PSII from the different N treatments did not differ significantly as interpreted from the rapid light curves, significant chlorophyll content were recorded. When nitrogen content between different plant parts were evaluated among the different treatments, significant variations were observed between different treatments and plant parts. Through results from this study, the optimum nitrogen combination for the optimum growth of C. guthrieae in the field has been established. doi:10.1016/j.sajb.2017.01.141

Pharmaco-synergistic potential of Moringa oleifera Lam. with antiretroviral therapies in managing HIV-1 infections A.R. Ndhlalaa,b, K. Celea, P.W. Mashelab, C.P. Du Plooya, H.A. Abdelgadira,b a Agricultural Research Council, Vegetable and Ornamental Plants, Private Bag X293, Pretoria 0001, South Africa b School of Agricultural and Environmental Sciences, Faculty of Science and Agriculture, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa E-mail address: [email protected] (A.R. Ndhlala) Despite the wide availability of antiretroviral therapy (ART), a number of people living with HIV still opt to adopt self-care practices or combinational therapies of ART and traditional medicines. Moringa oleifera Lam. (Moringaceae) is one such functional crop rich in protein, calcium, iron and vitamin C, used in the management of several medical and lifestyle conditions, including management of HIV infections. This study was designed to investigate the utility of M. oleifera leaf powder in management of HIV infections and possible interactions with ART (lamivudine, zidovudine, lopinavir and ritonavir). Moringa oleifera were sourced from different geographical regions as follows: Tanzania, South Africa and Thailand. It was grown under the same conditions in Pretoria, South Africa. Extracts were investigated for their ability to inhibit HIV-1 reverse transcriptase (RT) as single or combinational therapies. The results showed potential of the extracts as strong HIV-1 RT inhibitors with IC50 values ranging from 9 μg/ml to 79 μg/ml for water and 50% methanol extracts. A strong synergistic and additive interaction with ART was observed with Fractional Inhibitory Concentration (FIC) indices below 0.5 and within 0.5 and 1.0 for all extracts. Isobolograms constructed from the IC50 values yielded concave curves characteristic for strong pharmaco-synergism. As such, the combinational therapy of M. oleifera leaf powder and ART agents represents an attractive prospect for the development of new products for managing HIV-1 infections. doi:10.1016/j.sajb.2017.01.142


Survival strategies of selected alien invasive plants in parts of Thulamela Local Municipality, Limpopo Province, South Africa S. Ndou, M.H. Ligavha-Mbelengwa Department of Botany, School of Mathematical and Natural Sciences, University of Venda, Private Bag X5050, Thohoyandou 0950, South Africa E-mail address: [email protected] (S. Ndou) Survival strategy is an efficient means by which alien invasive plants which include Jacaranda mimosifolia, Psidium guajava, Eucaluptus paniculata and Ricinnus communis regain biomass lost during disturbance. The strategy for survival and growth which include sprouting, coppicing, root suckering and stem growth is dictated by the nature of plant. The aim of the study was to investigate the different regeneration strategies for the selected alien invasive species in the Thulamela Local Municipality in Limpopo. Thirty-five stump sprouts in each selected species were observed. Forty stem stocks were planted to determine whether they would regrow without applying fertilisers. Ten roots were also cut to assess if they would grow by root suckering. Sprouting was found to be the dominant strategy for growth in these alien invasive species. The current study would help underdeveloped rural communities since a number of studies have shown that alien invasive species positively contribute to rural economies when carefully managed in demarcated areas. doi:10.1016/j.sajb.2017.01.143

Systematics of the genus Tribulus (Zygophyllaceae) in southern Africa R. Nemandoa, J.S. Boatwrighta, A.R. Mageeb,c a Department of Biodiversity and Conservation Biology, University of the Western Cape, Private Bag X17, Bellville 7535, Cape Town, South Africa b South African National Biodiversity Institute, Private Bag X7, Claremont 7735, Cape Town, South Africa c Department of Botany and Plant Biotechnology, University of Johannesburg, PO Box 524, Auckland Park 2006, Johannesburg, South Africa E-mail address: [email protected] (R. Nemando) The genus Tribulus L. belongs to subfamily Tribuloideae (Zygophyllaceae) and currently includes approximately 25 species. The species favour warm, arid and semi-arid countries and are known to occur around the globe, with 13 species reported to be invasive, especially T. cistoides L., T. longipetalus L., T. terrestris L. and T. zeyheri Sond. In southern Africa 5 species are present, T. cristatus C.Presl, T. excrucians Wawra, T. pterophorus C.Presl, T. terrestris L. and T. zeyheri. This study aims to produce a comprehensive taxonomic treatment of the genus in southern Africa, including a key to aid identification of the species, distribution maps, and illustrations of key characters. The phylogenetic relationships were also examined using DNA sequence data based on three DNA markers i.e. nuclear ITS and chloroplast trnL-F and rbcL. Fruit morphology was found to be the most important character to distinguish between the species, at maturity the fruit divide into 5 indehiscent cocci with characteristic configurations of spines or wings in each species. Some confusion exists between T. excrucians and T. zeyheri, with some authors regarding them as conspecific. An overview of the five species, along with their relationships to other genera in the Tribuloideae will be presented. doi:10.1016/j.sajb.2017.01.144