SYSTEMATIC STUDIES IN THE GENUS SOLANUM IN AFRICA PETER-MARTIN LIND JAEGER B.Sc. A thesis presented to the Faculty of Science for the degree of Doctor of Philosophy. Department of Plant Biology, Faculty of Science, University of Birmingham. December, 1985. University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. 143205G SYNOPSIS Africa is a major centre of diversity in the large cosmopolitan genus S o 1 a n u m. The genus is an important component of the African flora, and, with a variety of uses, many of the species have a significant interaction with man. The objective of the present study was an elucidation of some of the many taxonomic problems found among the African species of the genus. The systematic history of the African species of Solanum is reviewed to provide an insight into the origins of the nomenclatural problems that pervade the genus. Taxonomic characters are described and assessed, and the phytogeography of the genus is discussed. The results of cross-pollinations and protein comparisons using polyacrylamide gel e1ectrop horesis and serological techniques are discussed. No new insights into the taxonomy of the African species were revealed by these experimental studies and the potential for further work is reviewed. An adaptation of earlier methods of analysis of serological data is described. In conclusion a taxonomic review is presented : species of Solanum occurring in Africa and the neighbouring islands are described accompanied by keys and comments on typification, distribution and synonymy. Around 80 species are believed to he autochthonous; three I species are . An index to the species names in the review lists 382 epithets. ACKNOWLEDGEMENTS This thesis is dedicated to my family who have given me all the support and encouragement that I needed to persevere, and to Liz for her patience and understanding and for making me get on with it. For the studies described in this thesis I have worked at the Department of Plant Biology, University of Birmingham and the herbarium, Royal Botanic Gardens, Kew. I am grateful to the authorities at both institutions for granting me the use of research facilities : in particular, my thanks are due to Prof. J. G.Hawkes and Prof. J. A. Callow of Birmingham, and Prof. J. P. M. Brenan and Prof. E. A. Bel 1 at Kew. I am indebted to the Science and Engineering Research Council for funding the CASE studentship with which I began these s tud ies. For supervision of my studies my thanks are due to Mr. F. N. Hepper of the R. B. G. , Kew, and Dr. R. N. Lester of the University of Birmingham. I am very grateful for the advice and assistance which has been offered throughout. In Birmingham, special thanks are due to Sarah Marsh, who looks after the living collections of Solanaceae at W i n t e r bourne, and who tended the plants grown for the present s tudy. I take this opportunity of thanking Robert Fish who has allowed me ample time to continue my studies and complete my thesis while in his employment at Primary Commodity Research Ltd. Furthermore, the use of the office word-processing facilities has been invaluable in preparing this thesis, and I am very grateful to Patricia Narriott for typing in my manuscript and dealing with all the numerous amendments. Finally, while working at Kew I have drawn on a great deal of advice, assistance and encouragement which has been offered by members of staff of the herbarium and the library, visitors to Kew and many other friends. It is not possible to record here all who have helped, and although my thanks extend to many more, I am particularly grateful to Sally Bidgood, Dick Brummitt, Charlie Jarvis, Peter Linder, and Nigel Taylor. CONTENTS 1 . Introduction 2. Systematic history 3. Taxonomic characters of African Solanum species 40 3.1 Habit, roots, stems and branching patterns 40 3.2 Leaves 4 5 3.3 Epidermal characters 50 3.4 Inflorescence 57 3.5 Perianth 60 3.6Androecium 63 3.7 Pollen 66 3.8Gynoecium 70 3.9 Fruits 73 3.10 Seeds 74 3.11 Cytology 75 3.12 Comparative chemistry 76 4. Phytogeography 112 Distribution of the family and the genus 113 Distribution of the genus in Africa 119 Habitats and adaptations 128 Reproductive biology 130 Dispersal, seed biology and weediness 132 Speciation 134 5. Experimental studies 139 5.1 Pollination studies 139 5.1.1 Introduction 139 5.1.2 Materials and methods 141 5.1.3 Results of cross-pollinations 144 5.1.3.1 Stylar incompatibility 146 5.1.3.2 Crosses within and between species 147 5.1.4 Discussion 153 5.2 Protein studies 160 5.2.1 Introduction 160 5.2.2 Materials 166 5.2.3 Polyacrylamide gel electrophoresis (PAGE) 167 5.2.3.1 Principles 167 5.2.3.2 Methods 169 5.2.3.3 Results 171 5.2.3.4 Discussion 178 5.2.4 Serotaxonomy 184 5.2.4.1 Principles 184 5.2.4.2 Methods 188 5.2.4.3 Re suits 193 5.2.4.4 Discussion 208 5.2.5 Conclusion to protein studies 223 Appendix to Chapter 5 6. Concluding discussion 7. Taxonomic survey of Solanum in Africa Solanum Key to the sections represented in Africa 251 Subgenus 1 Lye iosolanum 261 Subgenus 2 Solanum 263 Section 1 Af ricanum 264 Sec t i o n 2 Macronesiotes 267 Section 3 Lemurisolanuir. 271 Sec tion 4 Af rosolanum 273 Section 5 Bende rianum 283 Section 6 Solanum 2ii7 S ubgenus 3 Potatoe 312 Section 7 Petota 313 Sec tion 8 Basarthrum 316 Section 9 Jasminosolanum 318 Section 10 Normania 321 Submenu s 4 Brevantherum 324 Se c tion 1 1 Brevantherum 325 Sec tion 12 Pseudocapsicum 331 Subgenus 5 Leptostemonum 333 Section 1 3 Aculeigerum 335 Sect ion 14 Torva 337 Sec tion 1 5 Ani san therum 360 Section 1 6 Somalanuir. 363 Sec tion 1 7 Croat ianum 368 Section 1 8 Oliganthes 372 Sec t ion 1 9 I schy racanthum 417 Section 20 Melongena 420 Section 2 1 Monodolicbopus 458 Section 2 2 Nyc t e r ium 464 Sec t ion 2 3 Leprophora 468 Section 2 4 And r oce ras 470 Sec tion 2 5 Cryptocarpum 472 Section 2 6 Acanthophora 474 Section 2 7 Lasiocarpa 484 Index to the Solanum species names in Chapter 7 489 References 497 TABLES Page 2.1 'TABULA XXXII 1 in Magnol's Prodromus 18 2.2 Bitter's classification of S o1a n u m in Af r i c a 33 2.3 Seithe's arrangement of the taxa in the genus Solanum 38 3.12.1 The steroidal alkaloids and sapogenins reported in species of Solanum native or introduced to Africa 94 5.2.1(a) Groups of accessions of jL.2..i..§Jl.!i!!l species recognised by comparison of protein hand patterns after zone eleetrophoresis of the seed proteins 173 5.2.1(b) The diagnostic protein band patterns of the accession groups 177 5.2.2 Summary of the numbers of arcs of precipitate after immunoelectrophoresis 202 5.2.3 Details of double diffusion with absorption results 203 5.2.4 Summary of double diffusion with absorption results 218 FIGURES Page 3.2.1 Leaf venation and lohing in the genus Solanum 48 3.12.1 Outline of the hiosynthetic pathways inplants 81 3.12.2 Outline of the shikimate pathway 85 3.12.3 Outline of the acetate-mevalona t e pathway 88 3.12.4 Phytosteroid derivation 88 3.12.5 Examples of steroidal sapogenins ( spirostano 1 s) found in the genus Solanum 90 3.12.6 Examples of steroidal alkaloids found in the genus Solanum 91 3.12.7 Basic flavonoid structure 102 3.12.8 Proposed interrelationships between flavonoid types 102 4.1 The sequence of fragmentation of Pangaea and Gondwanaland 116 4.2 The main phytochoria of Africa and Madagascar 121 5.1.1 Cross-pollinations attempted hetween accessions of S.anguivi 147 5.1.2 Cross-pollinations attempted hetween accessions of S.ae thiopicum 148 5.1.3 Cross-pollinations attempted hetween accessions of S.anguivi and S.ae thiopicum 149 5.1.4 Cross-po11inations attempted hetween species belonging to section Oliganthes 150 5.1.5 Cross-pollinations attempted between species belonging to section Nelongena 151 5.1.6 Cross-pollinations attempted between species belonging to section Oliganthes and section Melongena 152 5.2.1 The patterns of wells cut in agar for (a) IEP and (b) DDA 191 5.2.2 (a) IEP reactions with antiserum R.122 against S.linnaeanum (S.210) 194 (b) IEP reactions with antiserum R.123 against S.marginaturn (S.256) 195 (c) IEP reactions with antiseru m R.124 against S.tomentosum (S.1155) 196 (d) IEP reactions with antiserum R.125 against S.giganteum (S.1208) 197 (e) IEP reactions with antiserum R.126 against S.violaceum (S.1489) 198 (f) IEP reactions with antiserum R.127 against S.macrocarpon (S.1653) 199 (g) IEP reactions with antiserum R.97 against S.incanum (S.50) 200 (h) IEP reactions with antiserum R.98 against S.aethiopicum (S.395) 201 5.2.3 Dendrogram showing species groupings derived from the analysis of data from DBA experiments 221 1.