C 1997 The Japan Mendel Society Cytologia 62: 103-113, 1997 Chromosomal Criteria and Taxonomic Relationships in the Solanaceae A. Badr 1 , *, S. F. Khalifa 2 , A. I. Aboel - Atta 3 , # and M. M. Abou -El - Enain 3 1 Botany Department, Faculty of Science, Tanta University , Tanta , Egypt 2 Botany Department , Faculty of Science, Ain Shams University, Cairo , Egypt 3 Biological Sciences and Geology Department , Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt Accepted November 6, 1996 The Solanaceae is a cosmopolitan family with several economically important species. There have been different views with regard to the taxonomic treatment of the family (Bentham 1976, Wettstein 1895, Baehni 1946) . Current treatments of the Solanaceae (Hunziker 1977, D'Arcy 1979, 1991) recognized two main subfamilies. The Solanoideae with curved embryos contained in flattened discoid seeds and the Cestroideae with straight or slightly bent embryos in subglobose seeds . The Solanoideae have been viewed traditionally as the primitive subfamily, with the divergence of the Cestroideae occurring early during its diversification (Murray 1945, D'Arcy 1977, 1991, Armstrong 1986). On the other hand, Olmstead and Palmer (1992) based on molecular results argued that the Cestroideae is more primitive than the Solanoideae . At the tribal level, Bentham (1876) divided the Solanaceae into five tribes, while Wettstein (1895) divided the family into two series A and B which comprise three and two different tribes respectively. D'Arcy's classification (1991) includes 13 tribes belonging to the two major subfamilies i.e. Cestroideae (five tribes) Solanoideae (eight tribes) in addition to a third minor subfamily; Nolanoideae which comprises one tribe. There has been much change regarding generic circumscription in the two main subfamilies. The most recent estimate (D'Arcy 1991) is 60 genera and about 1746 species for the Solanoideae and 36 genera and about 529 species for the Cestroideae . Little attention has been focused on the role of cytology in classification and phylogeny of Solanaceae . However , since Jorgenson (1928) made the first chromosome counts in the genus Solanum ; other counts have been made on several Solanaceous taxa (Fedorov 1969) . More recent studies was made by a number of authors, among them; Lessani and Panahi (1979) for Atropa , Ugborogho (1983) , Okoli (1988) and Bernardello et al. (1994) for Solanum , Husaini and Iwo (1990) for Datura , Pringle and Murray (1990) for Cyphomandra and Moscone (1993) for Capsicum . The present work deals with the contribution of cytological data to the taxonomic relationships in the two main subfamilies of the Solanaceae and relationships within and between taxa are discussed and their phylogeny based on chromosomal variation is proposed. Materials and methods Species investigated were mainly obtained as seeds from a number of Botanic Gardens , except those of Nicotiana glauca that were collected from the Western Mediterranean coastal region of Egypt. The sources of the species studied are given in Table 1 and voucher specimens are kept at the herbarium of Biological Sciences and Geology Department, Faculty of * To whom correspondence should be addressed. # Present address: The Teachers College, Jeddah , Saudi Arabia . 104 A. Badr , S. F. Khalifa , A. I. Aboel - Atta and M. M. Abou - El - Enain Cytologia 62 Education , Ain Shams University . Cytological preparations were carried out on root tips, obtained from seeds germinated on moist filter paper in Petri dishes , pretreated with 0.05% colchicine solution for 4 hr and fixed in 3 : 1 (v/v) ethanol : glacial acetic acid for 24 hr. Squash preparations were made using the Feulgen squash technique, mounted in Euparal and photographed using a Carl Zeiss photomicroscope III . Some karyotype criteria were measured from 5 to 10 chromosome complements; these are mean length in ƒÊm , mean chromosome arm ratio (r-value) and TF% (Huziwara 1962). The variation in chromosome length and arm ratio within the karyotype has been expressed by calculating the standard error (S.E.) of these parameters. Results and discussion A summary of the cytological data of the species studied is given in Table 1. Karyotypes are illustrated in Figs. 1-45. Among the 45 species studied the basic chromosome number of x = 12 is recorded in 32 species representing 8 of the 15 examined genera. The lowest number (x = 7) is recorded in the two Petunia species, while x = 8 is found in Cestrum parqui and in Nicotiana suaveolens , x = 9 in only N . alata , x =10 in both Nicandra physaloides and Nicotiana longiflora , x =11 in the two genera (three species) of Salpiglossideae , and x = 14 and 17 in the genus Hyoscyamus (three species). The chromosome count of 2n = 24 (x = 12) for Lycium ruthenicum , Solanum citrullifolium and S . mauritianum has been recorded for the first time in the present study, while other numbers recorded here confirm previous reports. Mean chromosome length (MCL) varies substantially between the species studied (Table 1). The lowest value (0.81±0.05 um) is recorded in Atropa acuminata , while the highest value (6.96 ± 0.43 um) is found in Cestrum parqui . Short chromosomes with MCL from 1-2 ƒÊm are recorded in most of the species studied i.e. Atropa (2 species) , Datura (4 spp.) , Hyoscyamus (3 spp.) , Lycium barbarium , Lycopersicon lycopersicum , Nicandra physaloides , Nicotiana (4 spp.) , Petunia hybrida , Physalis (4 spp.), Salpiglossis (one species), Solanum (10 spp.) and Withania (one species). Chromosomes with MCL values of 2-3 um are found in Browallia (2 spp.) , Capsicum (2 spp.), Lycium ruthenicum , Nicotiana (3 spp.) , Petunia axillaris and Solanum mauritianum , chromosomes with MCL values of 3-4 ƒÊm are recorded in both Browallia viscosa and Nicotiana longiflora , while long chromosomes are found only in Cestrum parqui . Except in the latter two species low SE values were recorded indicating a high degree of similarity in chromosome length in the majority of the species studied. Most species studied have karyotypes with metacentric to submetacentric chromosomes as indicated by their mean r. values, whereas the lowest value (1.17 ±0.02) is recorded in Atropa acuminata , the highest value (2.78 0.39) is found in Nicotiana acuminatum . The degree of karyotype asymmetry as indicated by TF% values ranged between 30.21% in Nicotiana acuminata and 46.17% in Atropa acuminata . SE of mean r.values indicates also the low degree of karyotype asymmetry in the majority of the species studied. There have been two different opinions concerning the evolutionary relationships among the two main subfamilies of Solanaceae . According to the floral vasculature , flower zygo - morphy and other morphological features, traditional views have considered the Solanoideae as ancestral (Melchior 1964, D'Arcy 1979, 1991, Armstrong 1986). On the other hand, Olmstead and Palmer (1992) argued that members of the Solanoideae share a more recent common ancestry than do members of the Cestroideae . Stebbins (1974) postulated that chromosomal evolution in most woody orders of angio - sperms has involved aneuploid increases from low basic number followed by polyploidization . Diversification of genera and additional speciation may then involve higher basic chromosome numbers. Consequently families with n = 12, 13, or 14 have been considered to be of a polyploid •} 1997 Chromosomal Criteria and Taxonomic Relationships in the Solanaceae 105 Table 1 . Sources of the species studied and summary of their cytological characteristics BGA = Botanical Garden of Faculty of Science, Ain Shams Univeristy , Cairo , Egypt ; BGB = Botanical Garden of Berlin University, Germany; BGH = Botanical Garden and Musium of Martin Luther Univeristy , Halle , Germany ; BGM = Botanical Garden of Marsellia University, France; CVR = Centre of Vegetable Research, Dokki, Giza, Egypt; GAM = Garden of Aromtic and Medicinal Plants, Delta Barrage, Egypt; HBN = National Botanical Garden , Belgium ; Mma . = Western Mediterranean Costal Region of Egypt ; 2n = Number of somatic chromosome , x = Basic chromosome number ; MCL = Mean chromosome length; r. value = arm ratio = Length of long arm/Length of shrot arm ; TF% = Total form percentage = Total short arm legnth /total length of all chromosomesX 100. 106 A. Badr , S. F. Khalifa , A. I. Aboel - Atta and M. M. Abou - El - Enain Cytologia 62 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Figs. 1-14. 1. Cestrum parqui , 2. Nicotiana acuminata , 3. N. alata , 4. N. glauca , 5. N . longiflora , 6. N. paniculata , 7 . N . rustica , 8 . N . suaveolens , 9 . N . tabacum , 10. Petuniaaxillaris , 11. P . hybrida , 12. Browallia americana , 13. B. viscosa, 14 . Salpiglossis sinuata . 1997 Chromosomal Criteria and Taxonomic Relationships in the Solanaceae 107 15 16 11 18 19 20 21 22 23 24 25 26 21 28 29 30 Figs. 15-30. 15. Datura innoxia, 16. D. mete!, 17. D.stramonium, 18. D. tatula, 19. Hyoscyamus albus, 20. H. muticus, 21. H. niger, 22. Lycium barbarum, 23. L. ruthenicum, 24. Nicandra physaloides, 25. Atropa acuminata, 26. A. belladonna, 27. Capsicum annuum, 28. C. frutescence, 29. Lycopersicon lycopersicum, 30. Physalis alkekengi. 108 A. Badr , S. F. Khalifa , A. I. Aboel - Atta and M . M. Abou - El - Enain Cytologia 62 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 Figs. 31-45. 31. Physalis ixocarpa , 32 . P . peruviana , 33. P. pruinosa , 34 . Solanum abutiloides , 35. S. americanum , 36 . S. avicular , 37 . S. citrullifolium , 38 . S. cornutum , 39 . S. dulcamara , 40 . S. macrocarpum , 41 . S . mauritianum , 42 . S. melongena , 43 . S . nigrum , 44 . S.sisymbriifolium , 45 . Withania somnifera . origin. However, Raven (1975) postulated x = 7 for the subclass Astridae , but proposed x = 12 for the Solanaceae with aneuploid reduction to x = 7 as in Petunia. Olmstead and Palmer (1992) pointed out that x = 12 should not be considered as ancestral in the Cestroideae , nor be 1997 Chromosomal Criteria and Taxonomic Relationships in the Solanaceae 109 interpreted as a parallelism with the Solanoideae . Rather x = 12 represents a synapomorphy uniting the Solanoideae with a part of the Nicotianeae (including Nicotiana but excluding Petunia) .