Available Online at http://www.recentscientific.com International Journal of CODEN: IJRSFP (USA) Recent Scientific

International Journal of Recent Scientific Research Research Vol. 10, Issue, 09(F), pp. 34924-34931, September, 2019 ISSN: 0976-3031 DOI: 10.24327/IJRSR Review Article

CHROMOSOMAL VARIATIONS AND SPECIATION IN INDIAN OF MILL. (SUBTRIBE CASSIINAE, ): A SYNOPTICAL REVIEW

*Sanjay Kumar Mishra

Department of Botany, Ewing Christian College, Prayagraj, Uttar Pradesh 211003, India

DOI: http://dx.doi.org/10.24327/ijrsr.2019.1009.4001

ARTICLE INFO ABSTRACT

Article History: Senna Mill, a widely distributed leguminous genus with about 350 species of herbs, shrubs and tree belongs to sub-tribe Cassiinae showing great variations in habit, morphology and chromosome Received 6th June, 2019 th number. In India genus is represented by about 43 species showing characteristic variations in Received in revised form 15 July, 2019 diploid chromosome number (2n = 24, 26, 28, 56 and 102) as well as in haploid chromosome Accepted 12th August, 2019 th complements (n = 12, 13, 14 and 28) with prevalence of 2n = 28 in different species. The genus Published online 28 September, 2019 exhibit the basic chromosome number x = 7 as well as secondary basic number of x = 13, and 14.

The secondary basic numbers have been evolved from the primary number by initial polploidization

followed by aneuploid and disploid modification of the secondary basic number during the course of Key Words: diversification and evolution. Two closely related species viz, with 2n = 28 and Senna, Cassiinae, Polyploidy, Disploidy, with 2n = 26 exhibit the best example of these type cytogenetical modification. Both the Speciation species resemble so closely to each other in their external morphology to the extent that they have been recognized conspecific by majority of taxonomist but they can be differentiated by holistic approach using various morphological and molecular markers. Present finding based on the review of the chromosome number of Indian species reveal that Senna tora (2n = 26) have been evolved from the widely distributed Senna obtusifolia (2n = 28) through aneuploid and prevalently by disploid modification of the chromosome during gamete formation. Thus initial polyploidization and subsequent aneuploidy and disploidy had played very important role in speciation of Indian species of Senna Mill.

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INTRODUCTION been delimited into six sections (Irwin and Barneby, 1982) and those related to Indian species have been placed under sections Senna Mill. a leguminous genus, previously recognized as Psilorhegma, Peiranisia, Chaemaefistula, and Senna (Singh, subgenera under genus L. sens. lat. has been elevated 2001). Phylogenetic analysis based on molecular markers to the level of genera under sub-tribe Cassiinae, tribe Cassieae, reveal that Senna is a monophyletic genus consisting of sub-family of family Fabaceeae. Irwin and polyphyletic sections except section Psilorhegma (Marazzi et Barneby (1981, 82) after establishing the sub-tribe Cassiinae al, 2006; Acharya and Panda, 2010). Different species under have segregated it into three genera viz, Cassia L. sens. str, genus exhibit difficult taxonomic interpretations particularly in Moench. and Senna Mill. This concept of floral features. Genus exhibits characteristic type of buzz trifurcation have been well recognized in the recent years pollination, heteranthery, poricidal anther dehiscence (Randell, 1988; 1989; 1990; Larsen and Hou, 1996; Acharya et mechanism, enantiostylous carpel (Dulberger, 1981; al, 2011). Senna Mill. is one of the most widely recognized Gottsberger and Gottsberger, 1988; Mishra et al, 2014). Many genus under family Fabaceae, comprising of approximately 350 Senna species also bears extrafloral nectary or gland on foliage species of herbs, shrubs and trees distributed throughout that attract ants that feed on it laid to the establishment of American, African, Asian and Australian continents (Rendell opportunistic mutualism protecting the from herbivores and Barlaw, 1998; Marazzi et al, 2006). In India 43 species of enable its diversification (Heil and Mckey, 2003). Senna have been reported of which 28 species including 5 endemic are endogenous and other species have been reported In spite of its wide distribution, the existing literatures reveal in cultivation (Singh 2001). Out of above 43 species 13 species that the chromosomal records are available merely for about including 5 endemic are of Asian, 18 of American, 6 of African one fourth species under genus Senna. Though there is record and 6 are of Australian origin (Singh, 2001). Genus Senna have of existence of diploid chromosome number of 2n = 22, 24, 26,

*Corresponding author: Sanjay Kumar Mishra Department of Botany, Ewing Christian College, Prayagraj, Uttar Pradesh 21003, India International Journal of Recent Scientific Research Vol. 10, Issue, 09(F), pp. 34924-34931, September, 2019 and 28 but 2n = 28 predominates in genus Senna (Frahm morphological markers in understanding the taxonomic Leliveld, 1960; Goldblatt, 1981; Biondo et al, 2005a; Resende relationship among morphologically similar species within et al, 2013; Rice et al, 2015; Cordeiro and Felix, 2018). genera. The present study was undertaken with the objective of Occurrence of polyploidy viz, 2n = 42, 52, 56 and 112 have simultaneous analysis of both the mitotic and meiotic also been reported in different species (Pantulu, 1947; Frahm chromosome counts of two closely related often synonymous Leliveld, 1953; Katayama, 1953; Chatterjee, 1969; Randell, species Senna obtusifolia and Senna tora along with common 1970; Matos et al, 2011; Resende et al, 2014). The prevalence rainy season weed growing abundantly as record of diploid chromosome in genus indicate the x =14 to be mixed population in the edaphoclimatic condition of Magh the basic chromosome number in the genus Senna. Resende et mela Parade ground, Prayagraj. The aim of the present study al. (2013) recorded the meiotic chromosome count of n = 12, was also to review the available chromosome count of other 13, 14, and 28 in different species of Senna and presence of n Indian species of Senna to establish the role of chromosomal =14 and 28 with frequent formation of multivalent in Senna variation in speciation and diversification of genus in Indian rugosa (G. Don.) Irwin & Barneby. support the frequent subcontinent. occurrence of polyploidy in genus Senna. Subfamily S. obtusifolia and S. tora are closely related species with Caesalpinoideae has basic chromosome number x = 7 is a intriguing taxonomic status and they have been regarded polyploid family where tetraploidy prevails in populations synonymous by some authors and two distinct species by (Bandel, 1974; Goldblatt 1981). The basic chromosome others (Randell, 1995). Though these two species are number x = 14 have been derived from x = 7 and thus it is the morphologically alike but they can be distinguished on the designated and accepted basic chromosome number of sub- basis of micro-morphological, ecological and biochemical tribe Cassiinae to which genus Senna belongs (Goldblatt, markers (Brenan, 1958a; De Witt, 1955; Mishra and 1981; Irwin and Barneby, 1982). Srivastava, 2009; 2010; 2011; 2015, Mishra et al, 2014, Mishra Senna is recognized as cytogenetically most variable and and Moses, 2018). The contradictory report on the taxonomic versatile genus under family Fabaceae (Atchison, 1951; status of these species can be resolved using cytogenetical Darlington and Wylie, 1955; Bir and Sidhu, 1967; Irwin and markers but due to lack of proper taxonomic identification and Turner, 1960; Tandon and Bhatt, 1971). Three basic consequent discrepancy in chromosome number the dilemma chromosome numbers viz, x = 6, 7 and 8 with parenthetically regarding the taxonomic status of these two closely related secondary basic number of 13 for sub-tribe Cassiinae (Cassia species is prevailing in India till today. Several investigations L. sens. lat.) has been recognized (Darlington and Wylie, have recorded diploid number of 2n = 26, 28 and haploid 1955). Irwin and Turner (1960), Sareen and Pratap (1975) number that of n = 13, 14 for both the Indian specimens of S. suggested the basic chromosome number of x = 7 for the genus obtusifolia and S. tora (Senn, 1938; Datta, 1933; Pantulu, 1960; Cassia L. sens. lat. (sub-tribe Cassiinae) supported by the Chatterjee, 1969; Bir and Kumari, 1982; Gupta and Gupta, actual existence of haploid number of n = x = 7 in subsection 1997). In the present study the specimen of both the species Xerocalyx and Senna auriculata (L.) Roxb. These authors have have been identified and collected from the mixed population reported the frequent occurrence of polyploids and aneuploids of same locality that provided better opportunity in evaluating in the species and on the basis suggested that any deviation and segregating these two species using holistic identification from x = 7 arise due to aneuploid loss or gain after markers based on morphological, micro-morphological, polyploidization. It indicates that polyploidy and aneuploidy palynological, ecological (Mishra and Srivastava, 2009; 2010; had played very important role in evolution and speciation of 2011; 2015; Mishra et al, 2014; Mishra and Moses, 2017) and sub-tribe Cassiinae. Polyploidy had played very important role cytogenetical approaches (present study) thus resolving the in speciation of angiosperms and about 25% of the total legume taxonomic riddles of these two closely related species. genera are polyploid (Senn, 1938). MATERIAL AND METHODS The plant specimen of Senna auriculata collected from Ceylon exhibit n = 7 (Jacob, 1940) where as Indian specimens have The plant materials for the study of mitotic and meiotic showed n = 14 (Pantulu, 1960; Tandon and Bhat, 1971). The chromosome count of S. obtusifolia, S. occidentalis and S. tora existence of different basic chromosome number in angiosperm have been collected in wild from the mixed population during taxa arise due to initial polyploidy followed by aneuploid the appropriate flowering and fruiting phenophases from the change in chromosome complements (Raven and Kyhos, Maghmela Parade ground area of Prayagraj district, Uttar 1965). Though aneuploidy is not very common in angiosperms Pradesh, India. The plant specimens were identified by yet it occurs frequently in leguminous genera. Each tribe monograph (Singh 2001) and herbarium vouchers were including Cassiiae of family Fabaceae (formerly deposited in the Duthie Herbarium, Department of Botany, Leguminosaeae) showed continuous series of occurrence of University of Allahabad, U.P, India. two or more than two basic chromosome numbers (Darlington Examined specimens and Wylie, 1955). Chaulagain and Sokya (2002) reported the abnormal cytological phenomenon arising due to nucleoprotein Senna obtusifolia (L.) Irwin and Barneby. India, UP, imbalance called cytomixis resulting from combination of Allahabad, S.K. Mishra UPAL 75006 (DHA); Senna distantly related gametes forming interspecific and intraspecific occidentalis (L.) Roxb. India, UP, Allahabad, S.K. Mishra, hybrid responsible for numerical instability and chromosomal UPAL 75002 (DHA); Senna tora (L.) Roxb. India, UP, polymorphism in Senna occidentalis and Senna tora. Allahabad, UPAL75004 (DHA).

Studies of chromosome number can be consider as one of the most important taxonomic tool supplementing with other 34925 | P a g e Sanjay Kumar Mishra., Chromosomal Variations and Speciation in Indian Species of Genus Senna Mill. (Subtribe Cassiinae: Fabaceae): a Synoptical Review

Table 1 List of the taxa (Indian species of Senna Mill.) reviewed for their diploid (2n) and haploid chromosome counts (n)

Taxon 2n n Source (Authors) Senn (1938), Irwin & Turner (1960) 24 12 Pantulu (1960), Datta &Datta (1973) S. alata (L.) Roxb 28 14 Irwin & Turner (1960) Biondo et al (2005a), Rasenda et al (2013) Singh (1979) 26 14 S. alexandrina Gars.ex. Mill. Frahm Leliveld(1960) 28 Rice et al (2015) S. artemisioides ( Gaud exDC) 28 Randell (1970), Bir & Kumari (1975), Rice et al (2015) Randell subsp. Artemisioides S. artemisioides (Gaud. Ex DC) Irwin & Turner (1970), Randell (1970), Rice et al (2015) 28 Randell subsp. cariacea S. artemisioides (Gaud ex DC) Irwin & Turner (1960), Randell (1970) 14 Randell subsp. petiolaris 28 Randell (1970) S. artemisioides (Gaud ex DC) 28, Randell (1970) Randell subsp. sturlii 42 28 Atchison (1951), Irwin & Turner (1960) S. atomaria (L.) Irwin & Barneby 24 Rice et al (2015) Pantulu (1960), Sareen and Pratap(1975), Jacob (1940) S. auriculata (L.)Roxb. 28 14 Pantulu (1940), Irwin and Turner (1960), Tandon and Bhatt (1970,1971), Rice et al (2015) S. bicapsularis(L.)Roxb. 28 Amato Avanzi (1956), Irwin & Turner (1960), Bandel (1974), Rice et al (2015) Irwin & Turner (1960) S. corymbosa (L.) Irwin & Barneby 28 14 Atchison (1951), Biondo et al (2005a), Resenda et al (2013) S. davidsonii (Singh) singh NA NA NA S. didymobotraya (Frewsen.)Irwin & Barneby 28 Irwin & Turner (1960), Bir and Kumari (1980), Rice et al(2015) S. divaricata (Nees &Bl.) Lock NA NA NA 26 Amato Avanzi (1956), Irwin & Turner (1960) S. fruticosa (Mill.). Irwin & Barneby 13 28 Rice et al (2015) Irwin & Turner(1960) S. hirsuta (L.) Irwin & Barneby var. hirsuta 28 14 Fraham Leliveld (1953), Biondo et al (2005a) 56 Fraham Leliveld (1953), S. hirsuta (L.) Irwin & Barneby var. leptocarpa (Benth.) 28 Abdi K,(unpublished) Irwin & Barneby S. holosericea (fresen) Greuter 28 Baquar et al (1966), Rice et al (2015) S. intermedia ( Sharma) NA NA NA Vivekananthan &Rathakrishnan) Singh S. italica Mill. subsp. italica 28 Fraham Leliveld (1953), Irwin &Turner(1960) Baquar et al (1966), Rice et al (2015), S. italica Mill. subsp. Micrantha (Brenan) Lock. 28 Ramnathan(1950),Baquar et al (1966), S. marilandica (L.) Link. 28 14 Irwin & Turner (1960) S. Montana ( Heyne ex Roth.)Singh 28 Rice et al (2015) S. multiglandulosa ( Jacq)Irwin & Barneby 24 Hus (1904),Saxton (1907), Sugiura(1931), Irwin & Turner (1951), Rice et al (2015) Irwin & Turner (!960) S. multijuga ( L.C. Richard)Irwin & Barneby 24 12 Biondo et al(2005a), Resenda et al(2013) Tandon & Bhat( 1970,1971), Pantulu (1960), * Present study. 24 13 Frahm Leliveld (1960), Biondo et al(2005a), Rice et al (2015) S. obtusifolia (L.) Irwin & Barneby 26 14 Irwin and Turner (1960), gupta & gupta(1971), Biondo et al (2005a),Rice et al (2015) 28 Irwin and Turner (1960), Biondo et al (2005a), Rice et al (2015) Muto (1929), Frahm Leliveld(1960), Bir & 13 26 Sidhu (1966), Gill & Husaini (Irwin & Turner (1960), Sareen & Pratap(1975)* Present study S. occidentalis( L.) Link 28 Biondo et al (2005a), Rice et al (2005) 14 Senn (1938), Pantulu (1940), Chatterjee (1969),Tandon & Bhatt( 1971), Matos et al (2011), Rice et al (2015) * Present study George & Bhavanandan S. pallida( Vahl.)Irwin & Barneby 28 14 (1993), Rice et al (2015) Irwin & Turner (1960) S. pendula( Willd.)Irwin & Barneby 28 14 Biondo et al (2005a), Resende et al (2013) S. planiticicola (Domin)Rendell 28 Rice et al (2015) 28 Frahm Leliveld (1960) S. podocarpa(Guillemin & Perrottet) Lock 16 Rice et al (2015) Irwin & Turner (1960) 26 Chatterjee (1969) S. septemtrionalis(Viv.)Irwin & Barneby 14 28 Irwin & Turner (1960),Tandon & Bhatt ( 1970,71), Biondo et al (2005a) Sareen & Pratap (1975)

S. siamea 14 Jacob(1940), Pantulu (1942), Amato avanzi(1956), Irwin & Turner(1960), Chatterjee (1969), Tandon and Bhatt(1970,71), 28 Resende et al (2013),Marcial & Cordeiro (2017) 24 Irwin & Turner (1960) S.. sophera (L.)Roxb. var. sophera 14 Kawakami (1930), Ramanathan (1955) 28 Pantulu(1960), Chatterjee(1969), tendon & Bhatt(1971), Resende et al (2013), Rice et al (2015) S. sophera (L.) Roxb 20 Datta (1933) Amato avanzi(1956), Arora(1960), Gill & Husaini(1981) 26 S. spectabilis(DC.)Irwin & Barneby var spectabilis) 14 Rice et al (2015) 28 Amato avanzi(1956), Arora(1960),Irwin & Turner (1960), Irwin (1964),Rice et al (2015) S. spectabilis (DC.)Irwin & Barneby var excela (Schard) 28 14 Bir & Kumari (1973, 1977) Pantulu(1960), Tandon & Bhatt (1970) 14 S. sulfurea(DC. Ex Collad)Irwin & Barneby 28 Nanda (1962) 16 Pantulu(1942), Atchison(1951), Rice et al (2015) 28 Pantulu (1960), Tandon and Bhatt(1970, 71), Bir and Kumari (1980) S. surattensis (Burm. f) Irwin & Barneby 56 Pantulu (1947) 32 Rice et al (2015) S. timoriensis(DC.) Irwin & Barneby 28 Rice et al (2015) Bir and Sidhu (1966), 26 Coleman& De Meniges(1980), * Present Study S. tora(L.) Roxb. 28 13 Chatterjee(1969), Tandon & Bhatt(1971),Rice et al (2015) * Present study 52 Jacob (1940), Chatterjee(1969), sareen (1974), Bir & Sidhu (1980) Katayama (1953), Miege (1960) S. uniflora( Mill.)Irwin & Barneby 26 Irwin & Turner (1960)

Mitotic preparations After germination when the root tips had grown upto 2 cm in length, they were excised on bright sunny days in between 10 The mitotic counts of each of the above specimens were and 11.30 a.m. and kept in saturated pretreatment solution of obtained from the fresh root apices collected from the para -dichlorobenzene for about 3-4 hours in refrigerator. The germinating one year old mature seeds. The seeds were preatreated root apices were washed thoroughly in distilled subjected to germination over the moist cotton wool in water and fixed in modified Carnoy’s solution containing petridishes. 34926 | P a g e International Journal of Recent Scientific Research Vol. 10, Issue, 09(F), pp. 34924-34931, September, 2019

Chloroform, Acetic acid and Absolute Ethanol in the ratio of been supported by several authors (Frahm Leliveld, 1960; Bir 3:1:6 and stored at room temperature for about 48 hours and and Sidhu, 1966; Sinha et al, 1972; Gill and Husaini, 1981) then stored in 70% ethanol. The stored root tips were rinsed in which was further supported by existence of diploid number of distilled water and hydrolyzed in N HCl solution at about 600C 2n = 26 (Kawakami, 1930; Biondo et al, 2005a; Rice et al, temperature for 15 minutes in water bath. The hydrolyzed root 2015). These finding were later contradicted by many authors apices were stained in warm 2% acetocarmine solution for on the basis of their finding of diploid number of 2n = 28 and about 45-90 minutes and the squashes were prepared from haploid number of n = 14 (Senn, 1938; Pantulu, 1940; 1960; stained root apices in 1% acetocarmine solution. Several Irwin and Turner, 1960; Chatterjee, 1969; Tandan and Bhat, preparations were made for each specimen and observations 1971; Sareen and Pratap, 1975; Bir and Kumari, 1982; Matos et were made under Nikon Micro-photographic apparatus at 40X al, 2011; Rice et al, 2015). The present finding reveal the and 100X (oil emersion) using 15X eye piece and existence of n =14 and 2n = 28 and presence of quadrivalents microphotographs were developed and colored photographs and chromosome laggard during meiosis indicate that Senna were edited using Adobe Photoshop software. occidentalis is a tetraploid species with 2n = 4x = 28 and n = 14, with basic chromosome number x = 7. Meiotic preparations S. obtusifolia and S. tora are two closely related species with Meiotic counts were obtained from the pollen mother cell intriguing and interesting . Linnaeus (1973) squashes. The unopened floral buds of appropriate size were recognized them as two distinct species Cassia obtusifolia and fixed in Carnoy’s solution containing Chloroform, absolute Cassia tora respectively but many authors have recognized C. ethyl alcohol and glacial Acetic acid in ratio of 4:3:1, for about obtusifolia as synonymous of C. tora (Bentham, 1871; Roxberg 24 hours in refrigerator. Anthers were excised and stained in 1832; Baker 1878) and since then the confusion persist warm solution of 2 % acetocarmine stain for about 45-60 regarding the taxonomic status of these two species. Later on minutes. Squashes were prepared from the stained anthers these species were segregated on the basis of geographical containing pollen mother cells. Slides were observed under distribution and some morphological features (De Wit, 1955;, Nikon Micro-photrographic apparatus at 40X and 100X Prain, 1897; Brenan, 1958a, b). S. tora have been considered as respectively using 15X eye piece and microphotographs were native of and Pacific islands while S. obtusifolia as native developed and the colored photographs were edited using of old world but due to flexibility and adaptability later has Adobe Photoshop software. gain wider distributions. Due to prevalent discrepancy in The mitotic and meiotic counts of chromosome available for chromosomal data the comparative cytogenetical studies based Indian species of genus Senna from existing literature have on meiotic and mitotic chromosomal behavior of these two also been reviewed (table, 1) to re-establish the basic related species was essential in addition to other existing chromosome number, original diploid and haploid morpholigical evidences. Literatures reveal the existence of chromosomal complements and range of variation in haploid number of n = 13, 14 and 2n = 26, 28 for both S. chromosome number in different species under genus Senna obtusifolia and S. tora (Datta, 1933; Senn, 1938; Jacob, 1940; and their evolutionary role in diversification and speciation of Fraham Leliveld, 1960; Irwin and Turner, 1960; Bir and Sidhu, the taxa. 1966; Chatterjee, 1969; Sareen et al, 1974; Coleman and Meninges, 1980; Bir and Kumari, 1982; Gupta and Gupta, RESULTS AND DISCUSSION 1997; Biondo et al, 2005a; Tandon and Bhat, 1971; Rice et al,

Senna Mill. is one of the most widely distributed leguminous 2015). In the present study the specimens of these two closely genus with about 350 species showing diverse range of habitat, related species were verified using possible morphological and habit and wide distribution. It differs in floral features from its micromorphological parameters to trace out the karyological closely allied genus Cassia Linn. and Chamaecrista Moench. differences to support their delimitation using relevant placed together under sub-tribe Cassiinae. It is monophyletic micromorphological markers undertaken in our previous genus divided into polyphyletic sections (Marazzi, 2006). studies. Apart from minor difference in morphology and habit as suggested by De Wit (1955) and Brenan (1967) previous The chromosome counts for Indian species of Senna have been micromorphological studies undertaken by us (Mishra and reviewed and both mitotic and meiotic chromosomal studies of Srivastava, 2009; 2010; 2011; 2015; Mishra et al, 2014; Mishra three species of Senna (S. obtusifolia, S. occidentalis and S. and Moses, 2017) reveal considerable differences in tora ) growing in mixed population have been undertaken. stomatotype, structure of anthers and carpel, features of their S. occidentalis (syn. Cassia occidentalis) is widely distributed pollen grains as well as in their chemical nature providing species in India growing abundantly in wasteland as rainy sufficient ground for their taxonomical distinctions. Present season weed that flower profusely during mid rainy season and cytogenetical studies reveal characteristic difference in their produced pods containing mature seeds at the end of monsoon meiotic as well as mitotic chromosome number and behavior. in the edaphoclimatic conditions of Prayagraj. It closely The uniglandular foliar form recognized as S. obtusifolia resemble with Senna sophera (L.) Roxb. (Singh, 2001) to the showed the haploid number of n = 14 (Fig. 1e, f, g and 2a) and extent that the later have been treated as synonymous to the diploid number of 2n = 28 and 56 (Fig. 2b, c) with prevalence former and named Cassia occidentalis L. var sophera ( L.) O. of centric and sub-centric chromosomes without any notable Kite. as well as Cassia occidentalis L. var. glabra DC. Both cytogenetic abnormality except for chromosomal stickiness the species have identical chromosome number and they can be during prometaphase. hardly differentiating by their morphological attributes. The first report on chromosome number of Senna occidentalis reveal the haploid number n = 13 (Muto, 1929) which have 34927 | P a g e Sanjay Kumar Mishra., Chromosomal Variations and Speciation in Indian Species of Genus Senna Mill. (Subtribe Cassiinae: Fabaceae): a Synoptical Review

genera as against their occurrence on short chromosomes in majority of angiospermic taxa (Battistini et al, 1999; Klant and Whittmann, 2000). Since the 2 chromosome bearing secondary constrictions are much longer than the rest of the chromosomes as seen during mitosis reflect that these two large chromosomes have been produced by the fusion of the terminal ends of one sub-metacentric chromosome with the end of telocentric chromosome reducing the diploid chromosome number in S. tora to 2n = 26. The present review on chromosomal number in Indian species of Senna Mill. based on the available literature evidences and the present investigations undertaken on three species indicate that Senna is multibasic group with x = 6, 7, 12, 13 and 14 but the x = 7 is the basic primary number that give rise to secondary basic number of x = 14 from which x = 13 and 12 have been evolved either through aneuploid loss or by disploidy (Atchison, 1951; Goldblatt, 1981, George and Bhavanandan, 1993). Existing literature showed that the sub- family Caesalpinoideae to which Senna belong itself is polyploid taxa in which tetraploids with basic chromosome x = 7 prevail from which intraspecific variations arise by disploidy (Bandel,1974; Goldblatt 1981).

Figure 1 S. occidentalis, (a, b) 14 bivalents during meiotic diakinesis/metaphase I, (c) 14 chromosomes at meiotic metaphase II, (d) diplotene stage with nucleolus; S. obtusifolia , (e,f) 14 meiotic bivalents during meiotic diakinesis/ metaphaseI, (g). 14 chromosome at meiotic metaphase II, (h). diplotene stage with single nucleolus; S. tora, (i-j) 13 meiotic bivalents during metaphase I, (k) 13 chromosome at meiotic metaphase II, (l) meiotic telophase II.

The biglandular foliar forms recognized as S. tora reveal the presence of n =13 (Fig. 1i, j, k) and 2n = 26 (Fig.2i, j, k,) with two large satellite and prevalence of sub-centric chromosomes (Fig. 2l). In some cases tripolarity with nonsynchronized anaphase II and chromosome laggard have been observed. It may arise due to abnormal spindle behavior. Senna occidentalis that showed close molecular affinity with S. tora (Acharya and Panda 2011) belonging to the section Chamaefistula showed n = 14 (Fig.1a, b, c) and 2n = 28 (Fig. 2. f, g, h).

Thus the present cytogenetical investigation reveal that S. obtusifolia and S. tora which have been treated conspecific or synonymous exhibit little difference in habit and morphology shows difference in their chromosome number, shape and size even under identical ecological conditions supporting their segregation as carried out by Jezovsek (1998) using isoenzymatic protein markers. Thus S. obtusifolia and S. tora are two distinct species in spite of their morphological identity. Figure 2 S. obtusifolia, (a) Diplotene stage with 14 bivalents,(b) Mitotic metaphase with 28 chromosomes, (c) mitotic metaphase with 56 chromosomes (d). mitosis in anther wall; S. obtusifolia (n = 14 and 2n = 28, 56) is the flexible and S. occidentalis (e) somatic cells with chromocenters (f-h) somatic cells with 28 adaptable species that have approached the wider geographical chromosome during mitotic metaphase; S. tora, ( i-k) somatic cells with 26 chromosomes during mitotic metaphase, (l). Mitotic metaphase with 2 satellite large chromosome distribution both in old and new world (Irwin and Turner, 1960; Singh 2001) could have given rise to S. tora (n = 13 and From the present study it is clear that the diploid number of 2n 2n = 26) by aneuploid loss of chromosome after formation of = 28 and haploid number of n = 14 prevail widely among the tetraploid through polyploidization during course of evolution species of Senna Mill. followed by 2n = 26 and n= 13 and it result in its speciation. supporting the existence of basic chromosome number to be x = 7 and secondary basic number to be 14 and 13. The Souza (2004) reported 2n =26 in S. obtusifolia with the secondary basic number n = 13 may arise due to initial occurrence of two satellite chromosomes with secondary polyploidization followed by disploidy or aneuploid loss of a constriction and the detachment of satellite have been resulted chromosomes during gamete formation and fusion of such two in higher chromosomal counts of 2n = 28. On contrary our gamete result in establishment of 2n = 26 or such other study reveals the presence of a pair of satellites on long chromosomal variations as observed by different authors. The submetacentric chromosome in S. tora like other leguminous 34928 | P a g e International Journal of Recent Scientific Research Vol. 10, Issue, 09(F), pp. 34924-34931, September, 2019 best example can be reflected in closely related S. obtusifolia 2n =28, wide distribution and genomic flexibility had given and S. tora. The former with 2n = 28 had given rise to the later rise to the later with 2n = 26 by initial polyploidization species with 2n = 26 through segmental aneuploid loss called followed by aneuploid loss or segmental disploidy. Thus initial disploidy. polyploidy followed by aneuploid changes and segmental disploidy had played significant role in diversification and Increase or decrease in chromosome complement may play consequent speciation of Indian species under genus Senna considerable role in speciation, diversification and evolution of Mill. a plant species. Any alteration in primary or secondary basic chromosome number may due to abnormality in mitosis or Acknowledgements meiosis but most often arise due to irregularity in meiosis such I am grateful to Professor (Retd.) G. K. Srivastava and as failure of synapsis and consequent recombination between Professor D. K. Chauhan, Head, Department of Botany, homologous chromosome pairs or due to non-disjunction of University of Allahabad, Prayagraj for being the constant chromosome during anaphase (Bretagnolle and Thompson, source of inspiration , encouragement and valuable guidance. 1995; Cai and Xu, 2007). It results in origin of aneuploid or Thanks are due to Dr. P. C. Srivastava, Head, Department of disploid chromosomsl complements in daughter cells and Botany and Dr. A. S. Moses, Principal, Ewing Christian daughter progenies. Aneuploidy results in change in basic College, Prayagraj for providing the facilities and other helps. chromosome number and consequent alteration in amount of DNA /genetic informations and phenotypes. Disploidy which is References popularly known as pseudoaneuploidy alter the chromosome number though chromosomal rearrangement such as Irwin, H. S, Barnebv, R. C, (1981) Tribe Cassieae Bronn. In chromosomal breakage and fusion but it does not alter the Polhill, R.M. & Raven, P.H. (Eds.) Recent Advances in amount of DNA content and genetic informations ahence Legume Systematics. Royal Botamic Garden. Kew.1, disploidy can be easily tolerated by plant species (Escudero et 97-106, al, 2013, De-Storme and Mason, 2014). Luo et al. (2012) had Irwin, H. S, Barnebv, R. C, (1982) The American Cassiinae- recognized disploidy as strong mechanism of chromosomal A synoptical revision of Leguminosae tribe Cassieae reduction in grasses. These disploid loss is achieved by subtribe Cassiinae in the New World. Mem. New York reciprocal translocation followed by end to end fusion of Bot. Gard. 35, 1-918. exchanging chromosomal region close to centromere of one Randell, B. R, (1988) Revision of the Cassiinae in Australia. chromosome and end of other chromosome followed by 1 Senna Miller. Sect. Chamaefistula (Colladon) Irwin & inactivation of one of the centromere also called insertional Barneby, J. Adelaide Bot. Gard. 11(1), 19-49. disploidy (Srinivachary et al, 2007; Schubert and Lysak, 2011; Randell, B. R, (1989) Revision of the Cassiinae in Australia. Luo, 2012). 1 Senna Miller. Sect. Psilorhegma (J. Vogel) Irwin & Barneby, J. Adelaide Bot. Gard. 12(2), 165-270. Polyploidy induces chromosomal rearrangements and other Randell, B. R, (1990) Revision of the Cassiinae in Australia. epigenetic changes responsible for phenotypic deviation and 3 Senna Miller. Sect. Senna. J. Adelaide Bot. Gard. 13, flexibility affecting chromosomal pairing and other inheritable 1-16. epigenetic modifications and due to genome plasticity these Larsen, K, Hou, D, (1996) Caesalpiniaceae. In Hou, Ding et. variations are easily tolerated by higher (Comai, 2005; al. Fl. Malesiana 12(2), 556-570, Leitch and Leitch, 2008; Hegarty and Hiscock, 2008). Acharya, L, Mukherjee, A. K, Panda, C. P, (2011) Separation Aneuploids exhibit greater phenotypic changes as compare to of the genera in the subtribe Cassiinae (Leguminoseae: polyploids due to genetic dosage imbalance that affect the Caesalpinioideae) using molecular markes. Acta regulatory proteins forming alter ate regulatory complexes Botanica Brasilica. 25, 223-233. results in phenotypic variations (Bircher, 2005). Polyploidy Randell, B. R, Barlow B. A, (1998) Senna pp 89-138. In: followed by aneuploid change in chromosomal complement is A.S. George (executive editor). very common in angiosperms and it play decisive role in their volume 12. Australian Government Publishing Service: evolutionary success and speciation (Wendel, 2000; Comai, Canberra Australia. 2005; Leitch and Leitch, 2008; Mayrose 2011). Marazzi, B, Endress P. K,, Queiroz, L. P, Conti, E, (2006)

Phylogenetic relationship with Senna (Leguminoseae, Cassiinae) based on three chloroplast DNA regions: CONCLUSIONS Pattern in evolution of floral symmetry and extrafloral nectarines. American Journal of Botany. 93, 288-303. Thus Senna Mill. a variable and versatile genus placed under Singh, V, (2001) Indian subtribe Cassiinnae, Journ. Econ. sub-tribe Cassiinae with wider geographical distribution have Taxon. Bot. (Additional Series) 18: Scientific Publishers prevalence of diploid chromosome number of 2n = 28 with Jodhpur. basis chromosome number x = 7 and secondary basic Acharya, L, Panda C. P, (2010) Validation of generic status chromosome number x = 14 and 13 have been evolved and of different taxa in sub-tribe Cassiinae (Leguminoseae: diversified by initial polyploidization producing secondary Caeasalpinioideae) using RAPD, ISSR and AFLP basic number of x = 14 from which other secondary basic markers. International Journal of Plant Physiology and number viz, x = 13 have been evolved by aneuploid or Biochemistry. 2(2), 18-28. disploid chromosomal changes giving rise to interspecific Dulberger, R, (1981) The floral biology of Cassia chromosomal variations within the genus. It is well reflected in didymobotrya and C. auriculata (Caesalpinioideae). closely related S. obtusifolia and S. tora where the former with American Journal of Botany 48, 1356-1360. 34929 | P a g e Sanjay Kumar Mishra., Chromosomal Variations and Speciation in Indian Species of Genus Senna Mill. (Subtribe Cassiinae: Fabaceae): a Synoptical Review

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