J. Indian bot. Soc. Vol. 91 (1-3) 2012 :133-137 SOMATIC KARYOTYPE POLYMORPHISM IN WITHANIA SOMNIFERA PAQUY (SOLANACEAE). AAKANKSHA VASHISTH AND A. K. SRIVASTAVA Department of Botany, C.C.S. University, Meerut, UP-250004. Eight accessions of Withania somnifera; 2n=48 were explored for the details of 3D somatic karyotype using length and volume of the chromosomes and the chromosome complements. These accessions showed symmetrical karyotype of and 1B types and exhibited significant amount of intraspecific karyotype polymorphism Key Words- Polymorphism, Somatic Karyotype, Withania somnifera The karyotype analysis gives an indication of chromosomes diversity and possible barriers to recombination (Burton and Powell, 1968). Withania somnifera belonging to family Solanaceae is of great medicinal importance. It has been commonly used in the traditional medicines of India. The species exhibits three ploidy levels 2n=2x=24, 2n=4x=48 and 2n=6x=72. The present paper deals with the detailed three dimensional analyses of somatic karyotype of eight accessions of this species. MATERIALS AND METHODS Root tips of the accessions collected from various places (Table-1.) were fixed in 3:1 absolute ethanol and glacial acetic acid having a pinch of ferric chloride after pre-treating with 0.05% colchicine solution for at least 24 hours. Fixed root tips were smeared and squashed in 1.5% aceto-carmine. The somatic karyotype were analysed from the squashed preparations. Photomicrographs were captured using computerized Nikon Image Analysis system. The following parameters were subjected for the details of 3-D somatic karyotype analysis- Total length of the chromosome of a complement (TLCC), Length of long and short arms and of the whole chromosome, Arm's ratio (AR), Total length of all short arms (TLSA), Total length of all long arms (TLLA), Centromeric index (CI), Gradient index (GI), Symmetry index (SI), Total chromatin length (TCL %), Relative length of the chromosome of a complement- (i). In relation to the longest chromosome of the cell (A), (ii). In relation to the longest chromosome out of all the cells studied (B). Mean radius of a chromatids of the chromosome of a complement, Volume of long arms, short arms and the whole chromosomes and Relative volume of the chromosome of a complement-(i). In relation to the volume of chromosome having highest value in the cell (A), (ii). In relation to the volume of chromosome having highest value out of all the cells studied (B). Total volume of the chromosome complements (TVCC). Arm's ratio, CI, GI, SI, TCL%, and relative length, and volume were worked out using the formulae as per Srivastava and Purnima (1990), Srivastava and Kalara (1996) and Singh and Purnima (2003). The volume of a chromosome was measured assuming it as two cylinders corresponding to two chromatids. The chromosomes of the complement were arranged on the basis of the total length into three types, A-C (A 2m, B=1-2m, C 0-1m). The chromosomes were again assorted into different types on the basis of the Received on December 5, 2011 Accepted on April 10, 2012
AAKANKSHA VASHISTH AND A. K. SRIVASTAVA Figures 1-8 Karyotype photomicrographs of accessions of W. somnifera. 1. W-1, 2. W-2, 3. W-3, 4.W-4, 5. W-5, 6. W-6, 7. W-7, 8. W-8. (Bar=10 μm). 134
SOMATIC KARYOTYPE POLYMORPHISM IN... 135 Figures 9-16 Idiograms of accessions of W. somnifera. 9. W-1, 10. W-2, 11. W-3, 12.W-4, 13. W-5, 14. W-6, 15. W-7, 16. W-8. (Bar=10 μm).
AAKANKSHA VASHISTH AND A. K. SRIVASTAVA 136 Table 1. List of accessions explored for karyotype analyses. Code Source Code Source W-1 Muzaffarnagar (U.P.) W-5 Bulandshar (U.P) W-2 Meerut (U.P.) W-6 Panipat (H.P.) W-3 Delhi W-7 Dehradun (Uttarakhand) W-4 Sardhana (U.P) W-8 Rishikesh (Uttarakhand) Table-2.Data related to karyotype of Withania somnifera. Acc. K.T TLCC TLSA TLLA GI TVCC TVSA TVLA K.F. W-1 W-2 W-3 W-4 W-5 W-6 W-7 W-8 1B 1B 106.99 93.45 84.63 106.95 62.50 98.39 89.19 93.56 47.33 42.50 39.06 47.43 27.06 43.90 39.25 41.39 58.96 50.95 45.57 59.52 35.43 54.50 49.94 52.17 123.52 134.15 97.62 122.5 121.74 155.88 107.89 112.82 17.66 15.52 14.06 17.7 10.38 16.34 14.81 15.54 37.16 33.36 30.66 37.23 21.24 34.46 30.81 32.49 46.29 39.99 35.77 46.72 27.81 21.39 39.20 40.96 34A(m)+2A(M)+10B(m)+2B(M) 22A(m)+12B(m)+12B(M)+2B(sm) 46B(m)+2(M) 30A(m)+4A(sm)+8B(M)+6B(m) 18B(M)+18B(m)+8B(sm)+4C(M) 30A(m)+2A(M)+14B(m)+2B(sm) 4A(M)+10A(m)+4B(M)+28B(m)+2B(sm) 2A(M)+24A(m)+4B(M)+12B(m)+6B(sm) arm's ratio as per Levan et al. (1964) into three different length with most of them of 'm' type types (M=1.0, m=1.0-1.7, sm=1.7-3.0), and. but, 'sm' and 'M' types were also present (Table W, X and Y mean radius of the chromatids of 2). Comparison of the length and volume of the complement (W = 0.10-0.20m, X = 0.20- gametophytic sets of the chromosomes of 0.44m, Y= 0.44-0.79m). different accessions revealed that a direct correlation between length and volume of the RESULT AND DISCUSSION chromosome existed. However, the accessions Withania somnifera is known to have varying differed from each other in relation to total chromosome numbers like 2n=2x=24 (Mohan length and volume of the chromosome Ram and Kamini 1964), 2n=4x=48 (Bhaduri complements. Most of the accessions had 1933, Gottschalk 1954, Baquar 1967, Bir and type of symmetrical karyotype (as per Sidhu 1980) and, 2n=6x=72 (Bir and Neelam Stebbins, 1958) with exception of two 1980). Data pertaining to TLSA, TLLA, accessions that exhibited 1B type. This TLCC, TVSA, TVLA, TVCC, GI and SI are observation is in agreement with Awatif et al. given in Table 2 along with the respective, (2000) and, Iqbal and Datta (2006) who also karyotype formulae (KFs) for different reported symmetrical karyotype and accessions. Photomicrographs of chromosome morphologically distinct chromosome types in complements of different accessions are the complements. The chromosome presented in Figures 1-8. Three dimensional complement of the accessions of this medicinal (3D) idiograms, prepared by plotting lengths species exhibited intraspecific polymorphism and widths of chromosomes of these that was expressed in the total length and accessions are shown in Figures 9-16. volume of the arms of the chromosomes and Variability within the individual chromosomes chromosome complement. with respect to the size, shape and position of REFERENCES centromere was found to be well marked. Awatif I, El-Nahas, Khalifa SF & Enain ME 2000 All the chromosomes of a complement were of Karyological studies on the Solanaceae. Pakistan
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