Caryologia. International Journal of Cytology, Cytosystematics and Cytogenetics 72(4): 69-78, 2019 Firenze University Press www.fupress.com/caryologiaCaryologia International Journal of Cytology, Cytosystematics and Cytogenetics ISSN 0008-7114 (print) | ISSN 2165-5391 (online) | DOI: 10.13128/cayologia-192 Citation: S. Heneidak, E. Martin, F. Altinordu, A. Badr, H.E. Eroğlu (2019) Chromosome counts and karyotype analysis of species of family Apocyn- aceae from Egypt. Caryologia 72(4): 69-78. doi: 10.13128/cayologia-192 Published: December 23, 2019 Copyright: © 2019 S. Heneidak, E. Martin, F. Altinordu, A. Badr, H.E. Eroğlu. This is an open access, peer- reviewed article published by Firenze University Press (http://www.fupress. com/caryologia) and distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All rel- evant data are within the paper and its Supporting Information files. Competing Interests: The Author(s) declare(s) no conflict of interest. Chromosome counts and karyotype analysis of species of family Apocynaceae from Egypt Samia Heneidak1,*, Esra Martin2, Fahim Altinordu2, Abdelfattah Badr3, Halil Erhan Eroğlu4 1 Department of Botany, Faculty of Science, Suez University, Suez, Egypt 2 Department of Biotechnology, Faculty of Science, Necmettin Erbakan University, Konya, Turkey 3 Department of Botany and Microbiology, Faculty of Science, Helwan University, Egypt 4 Department of Biology, Faculty of Science and Art, Bozok University, Yozgat, Turkey *Correspondence: sheneidak2000@yahoo.com Abstract. The chromosome counts of 13 species of family Apocynaceae in the flora of Egypt have been reported; one species from subfamily Periplocoideae and the other 12 species from subfamily Asclepiadoideae. The chromosome numbers are 2n = 22 for Periploca angustifolia, Glossonema boveanum, Pentatropis nivalis, Cynanchum acutum, Calotropis procera, Gomphocarpus sinaicus, Pergularia daemia and Pergularia tomen- tosa; 2n = 24 for Leptadenia arborea and Solenostemma arghel; 2n = 22, 44 for Caudan- thera edulis, Caudanthera sinaica and Desmidorchis acutangulus. The chromosome numbers and karyotype analyses were firstly reported in Leptadenia arborea (2n = 24). The polyploid nature was demonstrated by the prevalence of cells with 2n = 4x = 44 chromosomes in Caudanthera edulis, Caudanthera sinaica and Desmidorchis acutangu- lus. The chromosomes are median and submedian as most species in the Apocynaceae. The intrachromosomal asymmetry and interchromosomal asymmetry were estimated with MCA and CVCL values. In intrachromosomal asymmetry, Desmidorchis acutangulus is the most symmetrical karyotype, while Pergularia tomentosa is the most asymmet- rical karyotype. In interchromosomal asymmetry, Glossonema boveanum is the most symmetrical karyotype, while Cynanchum acutum is the most asymmetrical karyotype. Keywords. Apocynaceae, chromosome number, Egyptian flora, karyotype asymmetry. INTRODUCTION The family Apocynaceae comprises 366 genera and ca. 5100 species (Meve, 2002; Endress et al., 2014). This family is currently divided into five subfamilies; Periplocoideae, Asclepiadoideae, Apocynoideae, Rauvolfioideae, Secamonoideae (Endress and Bruyns, 2000; Endress et al., 2014). The major- ity of species represented in the Egyptian flora are classified in the two sub- families Periplocoideae and Asclepiadoideae. The subfamily Periplocoideae is a small group of species comprising only ca. 195 species in 33 genera (Henei- dak and Naidoo, 2015). On the other hand, Asclepiadoideae is the largest 70 Samia Heneidak et al. subfamily of the Apocynaceae and contains about 3000 species in 164 genera of five tribes. The tribes are divided into 15 subtribes (Meve, 2002; Endress et al., 2014). Chromosome data have been constantly used for systematic purposes but chromosome number alone is not sufficient to exactly trace the evolutionary history of taxonomic groups. However, comparative karyotype analysis of related species has traditionally been used to describe patterns and directions of chromosomal evolu- tion within plant groups and to infer the evolutionary role of chromosomal changes in plant evolution (Steb- bins, 1971; Badr et al, 1997; 2009; Eroğlu et al., 2013; Kamel et al. 2014). More detailed information about the karyotype has been found necessary in order to provide diagnostics criteria for the systematics and phylogeny of plants (Altay et al., 2017). In fact, karyological features are evaluated as important taxonomic characters only when provide additional information and allow conclu- sions about evolutionary events in the group of interest (Badr and Elkington, 1977; Peruzzi and Eroğlu, 2013). Survey of chromosome counts in the Apocynaceae in chromosome count reports, particularly the Index to Plant Chromosome Numbers of the Missouri Botani- cal Garden (http://www.tropicos.org/Project/IPCN) and the Chromosome Counts Database (CCDB) (http://ccdb. tau.ac.il) which is a community resource of plant chro- mosome numbers (New Phytol. 206(1): 19-26) as well as the old counts reported in Federov (1969) as well as the chromosome count reports that was frequenty pub- lished in the Journal Taxon indicated thatseveral authors have reported chromosome numbers of many species of the Apocynaceae. Several authors have reported chro- mosome numbers of many species of the Apocynaceae (Francini, 1927; Mitra and Datta, 1967; Fedorov, 1969; Arrigoni and Mori, 1976; Albers and Delfs, 1983; Albers and Austmann, 1987; Khatoon and Ali 1993; Liede 1996; Albers et al., 1993; Albers and Meve, 2001; Kamel et al., 2014). These studies showed that the family is karyologi- cally almost entirely homogenous, especially subfamilies Asclepiadoideae and Periplocoideae, with nearly 96% of the taxa investigated so far having chromosome comple- ments in multiples of a basic number of x = 11, with a few deviating numbers. Deviating chromosome numbers were reported with 2n = 18, 24 in Funastrum clausum (Jacq.) Schulr. and Funastrum cynanchoides (Decne.) Schulr. (tribe Ascle- piadeae) (Albers et al., 1993), 2n = 20 in Microloma inca- num Decne. Microloma calycinum E. Mey., Microloma sagittatum (L.) R. Br. and Microloma tenuifolium (L.) K. Schum. (tribe Asclepiadeae) (Albers et al., 1993) and 2n = 24 in Periploca graeca L. (subfamily Periplocoide- ae) (Pesci, 1971). In literature, x = 9 was only reported in Cynanchum acutum L. and Pergularia tomentosa L. (Fedorov, 1969). The deviating chromosome numbers, i.e. 2n = 24 and x = 9 that were found previously and in the present work were reported a deviating base chro- mosome numbers in the genera Cynanchum, Microloma, and Sarcostemma (Albers et al. 1993). These authors gave an account of previously published deviating chromo- some numbers in the Asclepiadaceae. In subfamily Asclepiadoideae, the polyploidy rate is approximately 6%. The polyploid species are mostly tetraploid (85%) with 2n = 44 and only a few are hexa- ploid with 2n = 66 (Albers and Meve, 2001). Albers (1983) reported the polyploid taxa in most of the genera of tribe Ceropegieae. Albers and Meve (1991) observed that the proportion of polyploid cells in the meristems of adventives roots is significantly higher than in the mer- istems of primary and secondary roots in genera Duvalia Haw., Hoodia Sweet ex Decne., Orbea Haw., Pectinaria Haw., Stapelia, Trichocaulon N.E.Br. and Tridentea Haw. High ploidy levels were recorded in Tylophora anomala N. E. Br.; for example the decatetraploid (2n = 132-154) and the hexaploid (2n = 66) (Meve, 1999). In Apocynaceae, the counting and measuring of small size of the chromosomes is difficult. The chromo- somes form a graded series with only very slight dif- ferences in morphology (Albers, 1983). Within a single karyotype the chromosomes are comparatively similar in size. The heterogeneous karyotypes were only found where chromosome sizes varied considerably in the sub- families Periplocoideae, Asclepiadoideae and Secamo- noide (Albers and Meve, 2001). In the present study, 13 species of the family Apo- cynaceae were investigated karyologically to determine the chromosome numbers and to compare with earlier results. In addition, the karyotype of the examined spe- cies growing in Egypt has been analysed using a number of chromosome characterizing parameters such as varai- tions in length, arm ration and centromeric asymmetry indices in order to gather more information that might help a better understanding of the taxonomic treatment of the species of Apocynaceae in the Egyptian flora. MATERIALS AND METHODS Plant materials Seeds of 13 species of Apocynaceae were collected from mature flowers from sites in their natural habitats as given in Table 1 and mapped as in Figure 1. Vouch- er specimens of the examined species are kept at Suez University Herbarium. In the two succulent species (Caudanthera edulis and Desmidorchis acutangulus), 71Chromosome counts and karyotype analysis of species of family Apocynaceae from Egypt the root tips of adventitious roots were collected from plants, except Caudanthera sinaica from seedlings. Cytogenetic procedure For cy tological preparations, seeds were germi- nated on moist Whatman paper and actively–grow- ing root tips were pre-treated in saturated aqueous α-bromonaphthalene at 4ºC for 24 hours, or in a solu- tion of 0.002 M 8-hydroxyquinoline at 18ºC for 5-6 hours. They were fixed in absolute ethanol:acetic acid (3:1) for at least one hour, hydrolysed in 1N HCl at 60ºC for 8 minutes and stained in Feulgen staining solution. The slides were mounted in Euparal for long-term stor- age (Martin et al., 2011). Photographs of chromosome spreads were taken using a Carl Zeiss Axiostar Plus microscope fitted with a Canon (Pc 1200 Power shoot A641) digital camera. The number of somatic chromosomes was carefully counted in five slides for each species. Karyotype analy- ses were made by using Bs200Pro Image Analysis Soft- ware. Homologous pairs of somatic chromosomes were determined according to their total and relative lengths for each species. The following parameters were used to characterize the chromosomes: long arm (LA), short arm (SA), total length (TL = LA + SA) and arm ratio (LA / SA). Total haploid lengths and mean haploid lengths were calculat- ed. For the karyotype formula, chromosomes were clas- sified using the nomenclature of Levan et al. (1964). Several karyotype symmetry indices have been applied to express the asymmetry of the karyotype. Karyotype asymmetries were estimated by mean centro- meric asymmetry (MCA) (Peruzzi and Eroğlu, 2013) and coefficient of variation of chromosome length (CVCL) (Paszko, 2006). The intrachromosomal asymmetry was Table 1. List of species examined and the localities from which plants used for chromosome counts were collected and date of collection. Taxa Date Locality 1. Periploca angustifolia Labillardiere 12.06.2009 El-Salûm: Wadi Salufa, 31º37’24’’N–25º09’00’’ E, Morsy et al. s.n. 2. Caudanthera edulis (Edgew) Meve & Liede 27.01.2009 Gebel Elba: Wadi Yahameib, 22º25’18’’N–36º18’33’’E, Morsy et al. s.n. 3. Caudanthera sinaica (Decne.) Plowes 10.05.2009 North Sinai: Gidda Pass, 30º13’06’’N–33º03’04’’E, Heneidak s.n. 4. Desmidorchis acutangulus Decne. 23.08.2009 Gebel Elba: Wadi Aideib, 22º15’00’’N–36º26’12’’E, Morsy et al. s.n. 5. Leptadenia arborea (ForssK.) Schweinf. 17.02.2009 Aswan: 24º05’00’’N–32º54’18’’E, Heneidak s.n. 6. Glossonema boveanum (Decne.) Decne. 09.04. 2009 Sharm El Sheikh: Nabq protectorate, South Sinai, 28º07’00’’N– 34º25’00’’E, Heneidak s.n. 7. Solenostemma arghel (Delile) Hayne 25.11. 2009 Dahab: South Sinai, 28º29’05’’N–34º31’18’’E, Heneidak s.n. 8. Pentatropis nivalis (J. F. Gmel.) D. V. Field & J. R. I. Wood 30.05.2009 Gebel Elba: Abu Ramad, 22º20’00’’N–36º34’00’’E, Morsy et al. s.n. 9. Cynanchum acutum L. 07.10. 2009 Suez: Shalufa, 30º07’03’’N–32º32’27’’E, Heneidak s.n. 10. Calotropis procera (Willd.) R. Br. 06.10. 2009 Ismailia: 30º64’00’’N–32º27’00’’E, 06.10.2009, Heneidak s.n. 11. Gomphocarpus sinaicus Boiss. 15.04. 2009 Saint Catherine: Wadi El Arbeen, South Sinai, 28º32’12’’N– 33º95’00’’E, Heneidak s.n. 12. Pergularia daemia (Forssk.) Chiov. 25.10. 2009 Gebel Elba: Wadi Acaw, 22º15’31’’N–36º21’00’’E, Morsy et al. s.n. 13. Pergularia tomentosa L. 13.12. 2009 Ismailia: Suez desert road, 29º38’33’’N–32º16’32’’E, Heneidak s.n. Figure 1. The distribution map of the studied species in Egypt. Periploca angustifolia (■); Caudanthera edulis, Desmidorchis acu- tangulus, Pentatropis nivalis, Pergularia daemia (♦); Caudanthera sinaica (▲); Leptadenia arborea (●); Glossonema boveanum, Sole- nostemma arghel, Gomphocarpus sinaicus (¶); Cynanchum acutum (▼); Calotropis procera, Pergularia tomentosa (▬). 72 Samia Heneidak et al. calculated with MCA = [mean (L – S) / (L + S)] × 100. The formula contains the length of long arm (L) and short arm (S) of each chromosome. The interchromo- somal asymmetry was calculated with CVCL = [standard deviation / mean chromosome length] × 100. Finally, a scatter diagram between intrachromosomal asymmetry (MCA) and interchromosomal asymmetry (CVCL) was drawn. RESULTS AND DISCUSSION The subfamily Periplocoideae is represented with one species in tribe Periploceae. The subfamily Asclepia- doideae is represented with 12 species in tribe Cerope- gieae and Asclepiadeae. The photographs illustrating the chromosomes of the studied species are shown in Fig- ures 2 and 3. The ideograms are given in Figure 4. The gametic and somatic chromosome counts of the investigated species in present and previous studies are given in Table 2. Detailed chromosomal data are given in Table 3. Chromosome numbers Table 2 summarizes the chromosome number and the previous counts for the studied species of Apocyn- aceae. Eleven of the 13 species examined here have 2n = 22, based on a basic number of x = 11. These results con- firmed previous records for other species, and therefore, it is clear that the dominance of a basic number of x = 11 and a majority of 2n = 22 is the base in the subfami- lies Periplocoideae and Asclepiadoideae. It is the first time to count the chromosomes of Leptadenia arborea (2n = 24); (Figure 2F). Both diploid chromosome number (2n = 22) and tetraploid chromosome number (2n = 44) cells were scored in the three succulent species, which belong to tribe Ceropegieae; i.e. Caudanthera sinaica, C. edulis (Figures 2C, 2D) and Desmidorchis acutangulus. Diploid number (2n = 22) is reported also in Caudanthera edu- lis by Albers and Meve (2001), in Caudanthera sinaica by Albers and Meve (2001), Kamel et al. (2014), and in Desmidorchis acutangulus by Albers and Delfs (1983), Albers and Meve (2001). However, tetraploid num- ber (2n = 44) is recorded also in Caudanthera edulis by Albers and Austmann (1987), in Desmidorchis acutangu- lus by Kamel et al. (2014), while in Caudanthera sinaica recorded in the present study only). Polyploidy is known to occur in 11 genera of subfamily Asclepiadoideae with eight genera belonging to tribe Ceropegieae (Albers and Meve, 2001). There are different patterns (mixoploidy) in terms of the number of chromosomes. This is prob- ably the state of the endopolyploidy that is the result of enderoduplication. No odd-number polyploidy was Figure 2. Photomicrographs of somatic metaphase chromosomes in root tip cells: Periploca angustifolia (A), Caudanthera sinaica (B), dip- loid Caudanthera edulis (C), tetraploid Caudanthera edulis (D), Desmidorchis acutangulus (E), Leptadenia arborea (F). Scale bar = 10 µm. 73Chromosome counts and karyotype analysis of species of family Apocynaceae from Egypt found. The diploid count supports the findings of Albers and Meve (2001); while the tetraploid count in this study supports the findings of Albers and Austmann (1987). Albers and Meve (1991) reported that the frequency of tetraploid cells in the adventitious roots is higher than in the primary and the secondary roots. This phenomenon may lead to a complete polyploidization of adventitious roots, and can be ascribed to ecological rather than mor- phological or genetic factors (Albers and Meve, 1991). Diploid chromosome number (2n = 22) is record- ed in Periploca angustifolia in this study and by Arri- goni and Mori (1976). Deviations from this number are absent in this species as reported before in subfamily Periplocoideae by Albers and Meve (2001). In the current study, three species; Glossonema boveanum, Pentatropis nivalis and Gomphocarpus sinaicus was also found to have a diploid chromosome number of 2n = 22 as scored by Albers and Meve (2001), Kamel et al. (2014) and oth- er four Gomphocarpus species examined by Albers and Meve (2001). The same for Cynanchum acutum was also found to have a diploid chromosome number of 2x = 22 as recorded by Kamel et al. (2014) and in other 25 Cyn- anchum species examined by Albers and Meve (2001). The old records of earlier numbers of n = 9 and 2n = 18 in Cynanchum acutum quoted in Francini (1927) and Federov (1969) as well as the count of 2n = 24 in Cyn- anchum virens (Albers et al., 1993) may be regarded as deviating numbers as argued by Albers et al. (1993). Calotropis procera was also found to have a diploid chromosome number of 2n = 22 as recorded by Fedorov (1969), Albers and Meve (2001) and Kamel et al. (2014). The other number of 2n = 26 recorded for this species by Bramwell et al. (1972) may be regarded as deviating number as argued by Albers et al. (1993). The two Per- gularia species were also found to have a diploid chro- mosome number of 2n = 22 as recorded by Albers and Meve (2001) and Kamel et al. (2014) in Pergularia dae- mia or by Albers and Meve (2001) in Pergularia tomen- tosa. The old records of earlier numbers of n = 9 in Per- gularia tomentosa quoted in Federov (1969) as well as the count of 2n = 24 in Pergularia daemia (Mitra and Datta, 967) may be regarded as deviating numbers as argued by Albers et al. (1993). Chromosome number of Leptadenia arborea was 2n = 24 in this report, while Albers and Meve (2001) found 2n = 22 in two Leptadenia species (L. pyrotechnica Dec- ne. and L. hastata (Pers.) Decne.). This may be regarded as deviating number as argued by Albers et al. (1993). The same for Solenostemma arghel was also found to have a diploid chromosome number of 2n = 24 in this study, while Kamel et al. (2014) found 2n = 22 in this species. Karyotype analyses The chromosomes of the examined species are all small with slight morphological differences among the complements of the studied samples. When com- pared the chromosome morphology among the spe- cies, the smallest mean chromosome length (2.60 µm) Figure 3. Photomicrographs of somatic metaphase chromosomes in root tip cells: Pentatropis nivalis (A), Glossonema boveanum (B), Sole- nostemma arghel (C), Cynanchum acutum (D), Pergularia tomentosa (E), Pergularia daemia (F), Gomphocarpus sinaicus (G), Calotropis pro- cera (H). Scale bar = 10 µm. 74 Samia Heneidak et al. Figure 4. Idiograms of studied species: Periploca angustifolia (A), Caudanthera sinaica (B), Caudanthera edulis (C), Desmidorchis acutangulus (D), Leptadenia arborea (E), Pentatropis nivalis (F), Glossonema boveanum (G), Solenostemma arghel (H), Cynanchum acutum (I), Pergularia tomentosa (J), Pergularia daemia (K), Gom- phocarpus sinaicus (L), Calotropis procera (M). 75Chromosome counts and karyotype analysis of species of family Apocynaceae from Egypt was observed in Cynanchum acutum of tribe Asclepia- deae. In contrast the largest mean length (6.51µm) was observed in Gomphocarpus sinaicus of tribe Asclepia- deae. Albers and Meve (2001) concluded that the aver- age karyotype size diminished from rather large chro- mosomes in the Periplocoideae to the smallest karyo- type length in the presumed most advanced tribe of the Asclepidoideae, the Asclepiadeae. The mean chromosomes length in Leptadenia arbo- rea is 2.61µm, whereas Albers and Meve (2001) noticed an average length of 0.72 µm in two Leptadenia species (L. pyrotechnica and L. hastate). In this study, mean chromosome lengths in Caudanthera sinaica, Desmidor- chis acutangulus and Caudanthera edulis were relatively larger (7.25, 6.14 and 5.38 µm, respectively). These three species also express evolutionarily basic morphological characters (Albers and Meve, 2001). Meve and Henei- dak (2005) reported that the average mean chromo- some length is (1.06-1.38 μm) in Apteranthes europaea of tribe Ceropegieae. The chromosomes of the three poly- ploid species studied here are usually smaller than those of diploid ones as reported before in polyploidy taxa by Albers and Meve (2001). A general tendency of size reduction can be seen starting with the presumably most primitive subfamily Periplocoideae to the more evolved Asclepiadoideae, and within the latter subfamily starting Table 2. The gametic and somatic chromosome counts of the investigated species in present and previous studies. Subfamily, Tribe, Subtribe Species Previous results Reference Present counts 2n Explanation n 2n Subfamily Periplocoideae Tribe Periploceae Periploca angustifolia — 22 Arrigoni and Mori (1976) 22 Detailed measurements Subfamily Asclepiadoideae Tribe Ceropegieae Subtribe Stapeliinae Caudanthera edulis — — 22 44 Albers and Meve (2001) Albers and Austmann (1987) 22 44 Detailed measurements Caudanthera sinaica — 22 Albers and Meve (2001), Kamel et al. (2014) 22 & 44 New count & detailed measurements Desmidorchis acutangulus — — 22 44 Albers and Delfs (1983), Albers and Meve (2001) Kamel et al. (2014) 22 44 Detailed measurements Subtribe Leptadeniinae Leptadenia arborea — — — 24 First report Tribe Asclepiadeae Subtribe Asclepiadinae Calotropis procera 11 — — — — 22 26 44 Fedorov (1969) Albers and Meve (2001), Kamel et al. (2014) Bramwell et al. (1972) Kamel et al. (2014) 22 Detailed measurements Gomphocarpus sinaicus — 22 Kamel et al. (2014) 22 Detailed measurements Pergularia daemia — — 22 24 Albers and Meve (2001), Kamel et al. (2014) Mitra and Datta (1967) 22 Detailed measurements Pergularia tomentosa 9 — — — 22 44 Fedorov (1969) Albers and Meve (2001) Kamel et al. (2014) 22 Detailed measurements Solenostemma arghel — 22 Kamel et al. (2014) 24 New count Subtribe Cynanchinae Cynanchum acutum 9 — — — 18 22 Fedorov (1969) Francini (1927) Kamel et al. (2014) 22 Detailed measurements Glossonema boveanum — 22 Albers and Meve (2001), Kamel et al. (2014) 22 Detailed measurements Subtribe Tylophorinae Pentatropis nivalis — 22 Albers and Meve (2001), Kamel et al. (2014) 22 Detailed measurements 76 Samia Heneidak et al. with the most primitive Fockeeae to the most advanced Asclepiadeae, a decrease in chromosome size has taken place (Albers and Meve, 2001). The chromosomes of most karyotypes are com- paratively similar in size. Only rarely were heterogene- ous karyotypes found where chromosome size varied considerably (Albers and Meve, 2001). The smallest arm ratio was observed in Desmidorchis acutangulus (1.06) and the highest one was observed in Leptadenia arborea (2.12). Cynanchum acutum has the smallest chromosome length as 1.67 μm and the biggest chromosome length is measured in Gomphocarpus sinaicus as 9.20 μm. Liede et al. (2002) also found that the chromosomes are gen- erally short and varying in length, one pair of the large sized chromosomes in Glossonema boveanum. In Apo- cynaceae, chromosomes are typically submetacentric, rarely acrocentric with one pair of chromosomes pos- sessing secondary constrictions with satellites (Albers, 1983; Albers and Meve, 2001). Albers and Meve (2001) found the smaller chromosomes in tribe Asclepiadeae, in particular the subtribes Asclepiadinae, Astephaninae and Metastelminae where mean length ranges from 0.70 to 1.15 µm. In tribe Ceropegieae, the MCA values indicated that Desmidorchis acutangulus is the most symmetrical kary- otype, while Caudanthera edulis is the most asymmetri- cal karyotype. Whereas, the CVCL values indicated that the most homogeneous centromere position is observed in Caudanthera sinaica. On the other hand the most heterogeneous centromere position is observed in Des- midorchis acutangulus. In tribe Asclepiadeae, the MCA values indicated that Glossonema boveanum is the most symmetrical karyo- type, while Pergularia tomentosa is the most asymmetri- cal karyotype. The CVCL values indicated that the most homogeneous centromere position is observed in Glos- sonema boveanum. On the other hand the most hetero- geneous centromere position is observed in Cynanchum acutum. In all tribe, the symmetrical and asymmetrical kar- yotypes are quite different. In parallel, a weak positive correlation is determined between MCA and CVCL (r = 0.120) (Figure 5). In Figure 5, three tribes of family Apo- cynaceae have different karyotypes in terms of asym- metry degrees: tribe Asclepiadeae with higher intrachro- mosomal asymmetry and interchromosomal asymmetry, tribe Ceropegieae with lower intrachromosomal asym- metry and interchromosomal asymmetry, one species of tribe Periploceae with relatively average intrachromo- somal and interchromosomal asymmetry. On the other hand the results need to be supported by data from more species, because the species number investigated (per tribe) is much too low. The possible origin of deviating chromosome num- bers called numerical aneuploidy are defects in cell divi- sion as anaphase lagging, nondisjunction or presence of B-chromosomes. B-chromosomes, which are also known as supernumerary chromosomes, are a major source of intraspecific variation in nuclear DNA (Jones et al., 2008). The general consideration is that B-chromo- somes are derived from the A-chromosomes. Probably, a B-chromosome may have originated from paracentro- Table 3. The measurement data of the studied Apocynaceae species. Species KF SC (μm) LC (μm) RL (%) SC-LC THL (μm) MCL (μm) CVCL MCA Periploca angustifolia 20m + 2sm 3.08 6.68 5.52-11.99 55.73 5.06 19.87 15.37 Caudanthera edulis 20m + 2sm 2.84 5.38 6.37-12.07 44.55 4.05 19.34 16.45 Caudanthera sinaica 22m 4.08 7.25 6.95-12.37 58.61 5.33 17.35 13.01 Desmidorchis acutangulus 22m 2.59 6.14 5.31-12.59 48.74 4,43 25.05 10.81 Leptadenia arborea 20m + 4sm 1.88 3.80 5.99-12.11 31.35 2.61 23.20 16.29 Glossonema boveanum 22m 2.70 4.88 6.59-11.92 40.97 3.72 16.63 11.20 Solenostemma arghel 24m 2.04 4.54 5.11-11.34 40.00 3.33 22.57 17.71 Pentatropis nivalis 22m 2.52 5.32 6.13-12.93 41.17 3.74 21.85 12.07 Cynanchum acutum 18m + 4sm 1.67 4.10 5.82-14.31 28.63 2.60 29.16 16.98 Calotropis procera 22m 2.08 5.37 5.53-14.26 37.67 3.42 26.27 15.19 Gomphocarpus sinaicus 22m 4.20 9.20 5.86-12.83 71.71 6.51 23.94 14.42 Pergularia daemia 22m 3.30 6.19 6.31-11.83 52.36 4.76 18.65 12.82 Pergularia tomentosa 22m 2.88 5.12 6.71-11.92 42.94 3.90 17.72 19.94 Abbreviations: karyotype formula (KF), shortest chromosome length (SC), longest chromosome length (LC), relative length (RL), total hap- loid chromosome length (THL), mean chromosome length (MCL). 77Chromosome counts and karyotype analysis of species of family Apocynaceae from Egypt meric region amplication of a fragmented A chromo- some or from A chromosome fusions. CONCLUSION With this study, new chromosome data were given for 13 taxa of family Apocynaceae. More karyological data are needed to understand the phylogeny of Apocynace- ae. In conclusion, some intrageneric relationships within Apocynaceae will clarify with comparative chromosomal analysis. Also, additional comparative high-resolution molecular cytogenetic studies will be necessary to clarify phylogenetic relationships between genera or species. ACKNOWLEDGEMENTS We would like to thank Prof. Dr. Ahmed Mursi Ahmed for collecting Caudanthera edulis, Desmidorchis acutangulus, Pentatropis nivalis and Pergularia daemia from Gebel Elba, in south east area of Egypt. REFERENCES Albers F (1983). Cytotaxonomic studies in African Ascle- piadaceae. Bothalia 14: 795-798. Albers F, Austmann M (1987). Chromosome number reports XCV. Taxon 36: 494-496. Albers F, Delfs W (1983). In IOPB chromosome number reports LXXXI. Taxon 32: 667-668. Albers F, Liede S, Meve U (1993). Deviating chromosome numbers in Asclepiadaceae. Nord J Bot 13: 37-39. Albers F, Meve U (1991). Mixoploidy and cytotypes: A study of possible vegetative species differentiation in stapeliads (Asclepiadaceae). Bothalia 21: 67-72. Albers F, Meve U (2001). A karyological survey of Ascle- piadoideae, Periplocoideae, and Secamonoideae, and evolutionary considerations within Apocynaceae s.l. Ann Missouri Bot Gard 88: 624-656. Altay D, Eroğlu HE, Hamzaoğlu E, Koç M (2017). Karyo- type analysis of some taxa of Dianthus section Verrucu- losi (Caryophyllaceae, Sileneae). Turk J Bot 41: 367-374. Arrigoni PV, Mori B (1976). Numeri cromosomici per la flora Italiana: 366-374. Inform Bot Ital 10: 46-55. Badr A, Elkington TT (1977). Variation of Giemsa C-band and fluorochromes banded karyotypes and relationships in Allium subgenus Molium. Plant Syst Evol 128: 23-35. Badr, A, Kamel, EA, Garcia-Jacas, N (1997). Chromo- somal studies in the Egyptian flora. VI. Karyotype features of species in subfamily Asteroideae (Aster- aceae). Compositae Newsletter 30: 15-28. Badr, A, El-Shazly, HAH, Kamel, EA (2009). Chromo- somal studies in the Egyptian flora. VII. Karyotype analysis of species in the two tribes Chicorieae and Cardueae of Asteraceae. Egypt. J. Bot. 49: 71-86. Bramwell D, Humphries CJ, Murray BG, Owens SJ (1972). Chromosome studies in the flora of Macaro- nesia. Bot Notiser 125: 139-152. Endress ME, Bruyns PV (2000). A revised classification of the Apocynaceae s.l. Bot Rev 66: 1-56. Endress ME, Liede-Schumann S, Meve U (2014). An updated classification for Apocynaceae. Phytotaxa 159: 175-194. Eroğlu HE, Şimşek N, Koç M, Hamzaoğlu E (2013). Kar- yotype analysis of some Minuartia L. (Caryophyllace- ae) taxa. Plant Syst Evol 299: 67-73. Fedorov AA (1969). Chromosome numbers of flowering plants. Leningrad: Academy of Science of the USSR, Komarov Botanical Institute. Francini E (1927). L’embriologia del Cynanchum acutum L. Nuovo Giorn Bot Ital 34: 381-395. Heneidak S, Naidoo Y. (2015). Floral function in relation to floral structure in two Periploca species (Periplo- coideae) Apocynaceae. Turk J Bot 39: 653-663. Jones RN, Viegas W, Houben A (2008). A century of B chromosomes in plants: so what? Ann Bot 101: 767- 775. Kamel EAR, Sharawy SM, Karakish EAK (2014). Cyto- taxonomical investigations of the tribes Asclepiadeae Figure 5. Scatter diagram between MCA and CVCL: Periploca angus- tifolia (A), Caudanthera edulis (B), Caudanthera sinaica (C), Desmi- dorchis acutangulus (D), Leptadenia arborea (E), Glossonema bove- anum (F), Solenostemma arghel (G), Pentatropis nivalis (H), Cynan- chum acutum (I), Calotropis procera (J), Gomphocarpus sinaicus (K), Pergularia daemia (L), Pergularia tomentosa (M). 78 Samia Heneidak et al. and Ceropegieae of the subfamily Asclepiadoideae- Apocynaceae. Pak J Bot 46: 1351-1361. Khatoon, S and Ali, SI (1993). Chromosome Atlas of the Angiosperms of Pakistan. Department of Botany, University of Karachi, Karachi. Liede, S (1996) A Revision of Cynanchum (Asclepiadace- ae) in Africa. Ann Missouri Bot Gard 83(3): 283. Levan A, Fredga K, Sandberg AA (1964). Nomenclature for centromeric position on chromosomes. Hereditas 52: 201-220. Liede S, Meve U, Täuber A (2002). What is the subtribe Glossonematinae (Apocynaceae: Asclepiadoideae)? A phylogenetic study based on cpDNA spacer. Bot J Linn Soc 139: 145-158. Martin E, Çetin Ö, Akçiçek E, Dirmenci T (2011). New chromosome counts of genus Stachys (Lamiaceae) from Turkey. Turk J Bot 35: 671-680. Meve U (1999). Tylophora anomala (Asclepiadaceae) - a cytologically anomalous species. Syst Geogr Pl 68: 255-263. Meve U (2002). Species numbers and progress in ascle- piad taxonomy. Kew Bull 57: 459-464. Meve U, Heneidak S (2005). A morphological, karyologi- cal and chemical study of the Apteranthes (Carallu- ma) europaea complex. Bot J Linn Soc 149: 419-432. Mitra K, Datta N (1967). In IOPB chromosome number reports XIII. Taxon 16: 445-461. Paszko B (2006). A critical review and a new proposal of karyotype asymmetry indices. Plant Syst Evol 258: 39-48. Peruzzi L, Eroğlu HE (2013). Karyotype asymmetry: again, how to measure and what to measure? Comp Cytogen 7: 1-9. Pesci G (1971). In numeri cromosomici per la flora Itali- ana. Inf Bot Italiano 3: 124-157. Stebbins GL (1971). Chromosomal evolution in higher plants. London: Edward Arnold Ltd. Substantia An International Journal of the History of Chemistry Vol. 2, n. 1 - March 2018 Firenze University Press