Conference Abstracts South African Association of Botanists (SAAB) – Annual Meeting 2012 Abstracts of papers and posters presented at the 38th Annual Congress of the South African Association of Botanists held at the University of Pretoria, Pretoria, 15-18 January 2012 The presenter of multi-authored papers is underlined ★ Awards made to students Plenary lectures CO 2 as a driver of global change in African ecosystems W. Bond Botany Department, University of Cape Town, South Africa Savannas evolved under low atmospheric CO 2 which fa- vored C4 grasses over their C3 predecessors. Over the last cen- tury, CO 2 has increased to levels exceeding those recorded in paleo-atmospheres over at least the last million years. In the coming century they are expected to increase to levels last seen in the Eocene, more than 30 Ma ago. These anthropogenic increases in CO 2 are likely to have profound effects on African ecosystems and especially C4 grassy ecosystems. Here I review studies of the contributions of increasing CO 2 to vegetation change in African ecosystems. Simulation studies, glasshouse experiments, and long term field experiments point to signifi- cant CO 2 effects on woody plant expansion, especially in higher rainfall savannas. The future of the C4 grassy biomes in Africa looks very uncertain in a high CO 2 world. Desertification, carbon sequestration and job creation: The science behind the Subtropical Thicket Restoration Project R.M. Cowling a , A. Mills b , A. Sigwela a , S. Pierce a , M. Van der Vyver a , C. Marais c a Restoration Research Group, Department of Botany, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Eliza- beth 6031, South Africa b Restoration Research Group, Department of Soil Science, Stellen- bosch University, Private Bag X1, Matieland 7602, South Africa c Natural Resource Management, Department of Environment Affairs, Parliament Towers, 103–107 Plein Street, Cape Town 8000, South Africa Subtropical thicket ecosystems dominated by Portulacaria afra (spekboom) store amounts of carbon comparable to forest ecosystems that receive up to three times their annual rainfall. This remarkable finding – an outcome of SANBI's Conserva- tion Farming project – led to the initiation of research on the potential to finance the restoration of degraded spekboom thicket via the emerging carbon economy. The research, which is funded by the Natural Resources Management Pro- gramme of the Department of Environment Affairs, was con- ceptualized as a monitoring and evaluation program, in order to facilitate social learning and adaptive management for cata- lyzing large-scale, biome-wide restoration in the private sector. This program was formalized as the Subtropical Thicket Resto- ration Project (STRP), a learning organization comprising man- agers and researchers. Here I describe a decade of biophysical research that has culminated in the validation of the world's first carbon sequestration project involving the restoration of a desertified ecosystem. The STRP has successfully catalyzed an initiative that is consistent with the South African govern- ment's commitment to create employment via a green economy. Regulation of carotenoid biosynthesis and its connection to the biogenesis and function of plastids J. Hirschberg Department of Genetics, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel Carotenoid pigments are essential components of the photo- synthetic apparatus and thus are present in all green tissues of plants. These molecules are synthesized within plastids from the central isoprenoid pathway by enzymes that are nuclear encoded. In addition to their primary functions in photosynthe- sis, carotenoids play essential roles in plant reproduction by furnishing flowers and fruits with distinct pigmentation and as precursors for volatiles and aroma compounds that attract animals. Two phytohormones, abscisic acid (ABA) and 0254-6299/$ -see front matter © 2012 SAAB. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.sajb.2012.02.002 Available online at www.sciencedirect.com South African Journal of Botany 79 (2012) 173 – 240 www.elsevier.com/locate/sajb