Saravanakumar. K, Cytotaxonomical and Karyomorphological Studies in some Aquatic Members of Commelinaceae, Int.J.Curr.Biotechnol., 2013, 1(7):11-17. International Journal of Current Biotechnology ISSN: 2321 - 8371 Journal Homepage : http://ijcb.mainspringer.com Cytotaxonomical and Karyomorphological Studies in some Aquatic Members of Commelinaceae Saravanakumar. K* Botany Wing-DDE, Annamalai University, Tamilnadu, India -608002. ARTICLE INF O ABSTRACT The study was carried out to clarify karyologically a part of the speciation system in Commelinaceae. There are very few karylogical studies recorded earlier but the Article History: intraspecific structure has not been clarified karyologically, though the chromo- Received 12 September 2013 some number variable within the species. The genus Amischophacelus is repre- Received in revised form 14 September 2013 sented by only two species namely A. axillaris and A.cucullata and both are distin- Accepted 20 September 2013 guished by the presence of cucullate leaf sheath and seed characters. The genus Commelina is readily distinguished from other genera by means of its foliaceous Available online 28 September 2013 bracts. In general this genus is a distinct one with several complexes. The chromo- somes are mainly of medium size with mostly sub-median primary constrictions. In this respect it has close similarity with Murdannia where a dominant line of x = 10 is indicated. The aim of the present study is to supply further karyological information about aquatic members of Commelinaceae. Not only the genera differ among themselves in possessing various types of chromosomes in various combi- Key words: nations but also different species of a particular genus and even the varieties of Cytotaxonomy,Karyomorphology, a particular species possess distinct karyotypes of chromosomes. Based on the Aquatic plants, Commelinaceae. present study, morphological and karyological characters there are two cytotaxonomical groups have been formed, they are, Group I (Amischophacelus axillaris and A. cucullata) and group II (Commelina diffusa, C. diffusa ssp. aquatica) and M. nudiflora). Introduction Materials and Methods The family Commelinaceae is commonly known as Spiderwort family. It comprises about 37 genera and The plant species 1.Amischophacelus axillaris, 2. A. 600 species. The family members are widely distributed cucullata, 3. Commelina diffusa, 4. C. diffusa ssp. aquatica in tropical and subtropical regions of the world and and 5. Murdannia nudiflora were collected at the extend to temperate regions. It has three major centers seedling stage (5cm length) and allowed to grow in of taxonomic diversity namely 1.Tropical Africa, 2. earthen pots in the Botanical Garden of the Annamalai Mexico and Northern Central America and 3. The Indian University. For mitosis, root tip squash was made from subcontinent. Only 6 genera (Aneilema, Buforrestia, the excised root tips collected from potted plants Commelina, Floscopa, Murdannia and Pollia) are between 9.30 a.m. and 11.30 a.m. and thoroughly indigenous species in both the New world and Old world washed in running water to remove the sand. They were (Faden,1978). In Tamilnadu State of India, most of the pre-treated in 0.002m 8-Hydroxyquinoline at 40 C for 3 members are found as weeds in cultivated field and hours. Then, the root tips were cleanly washed in few taxa grow as wild species in lower elevations as distilled water and fixed in Carnoy’s Fluid (1:3 acetic well as temperate regions of Eastern and Western Ghats. acid: ethyl alcohol) mixture for 24 hours. Among the species of Commelinaceae available in Again, the root tips were washed in distilled water. Then Tamilnadu only some of the taxa have been the root tip squashes were prepared following iron cytologically investigated so far. Even though the alum haematoxylin squash technique (Marimuthu and chromosome numbers were known, the morphology of Subramaniam, 1960). Observations were made by using the chromosomes has not been studied in detail in most Meiji RM-T Trinocular light microscope with the of the species. The present study was undertaken on magnification of X 1250 with an eyepiece lens (12.5x) the members available in Cuddalore District of Tamil and an objectives of oil immersion lens (100x). The nadu in order to understand the cytological characters important plates were microphotographed. For the of the family. assessment of the number and morphology of chromosomes, ten metaphase plates in each species were studied. Measurement of all the chromosomes in *Corresponding author. a complement was recorded and the homologous Email address: [email protected] 11 Int.J.Curr.Biotechnol. Volume 1; Issue 7; Sep, 2013 chromosomes were paired and arranged in decreasing fusiform at apex, naked. Fruits capsule oblong, order of length. Idiograms were made in decreasing ellipsoid, beaked, shortly stipitate pointed end at the order of length. tip without any depression. Seeds oblong, compressed, truncate at the base, apex rounded, dark brown shining. The observation of somatic chromosomes at metaphase were arranged and classified based on the centromeric 3. Commelina diffusa Burm. F. positions of each homologous pairs and individual Antals clawed, anterior not clawed. Stamens 6, of 3 chromosome in case of heterologous were arranged fertile anterior, 3 staminodes posterior; filaments pale according to Levan et al., (1964). Karyotype asymmetry violet, slender; anthers small. Ovary 3-celled, of which has been estimated using the equation of Huziwara two 2-ovulate, the third 1-ovulate. Fruits capsule 5- (1962). seeded, oblong, acuminate and coriaceous. Seeds oblong, cylindric, tuberculate or reticulate brown. Morphological Observations 4. Commelina diffusa ssp. aquatica Morton 1. Amischophacelus axillaris (L.) R. Rao et Kamm. Annused; peduncles longer, equalling or exceeding the Annual, suberect. Root fibrous. Stem stout or slender, spathe. Flowers borne on exceptionally long pedicels; diffusely branched, branches creeping below, glabrous sepals 3, anterior-2 broadly ovate, jointed at the base or sparsely hairy, often coloured, internodes long. and posterior –1 boat shaped; petals 3, large rich blue Leaves sessile, narrowly linear to linear lanceolate, in colour. Stamens 3, staminodes 3; filaments slender; acute or acuminate, flat, glabrous or hairy; sheath anthers small and blackish margin. Ovary 2-celled of inflated, ciliate. Inflorescence in cymes reduced to which two are 2-ovulate and third one 1-ovulate. Fruits axillary fascicle. Flowers with small linear bracteoles, capsule 5-seeded, oblong and acuminate. Seeds oblong, almost concealed in the leaf sheaths; sepals 3, cylindric, tuberculate, brown. spathulate, lanceolate, acuminate; petals 3, pink-blue or rose purple; filaments fusiform, bearded; style 5. Murdannia nudiflora (L.) Brenan fusiform at apex, naked. Fruits capsule oblong, Annual, erect. Root fusiform, thick and tuberous. Stem ellipsoid, beaked, shortly stipitate pointed end at the glabrous with long internodes. Leaves radical, linear, tip without any depression. Seeds oblong, compressed, finely acuminate, flat, striate, narrowed into a short or truncate at the base, apex rounded, dark brown shining. long sheath. Inflorescence in terminal panicles, stout, sparingly branched; Flowers bisexual, actinomorphic, 2. Amischophacelus cucullata (Roth) R. Rao et Kamm. bracts caducous; sepals 3, free, ovate, oblong, acute, concave; petals 3, equal pale purplish blue, Annual, suberect. Root fibrous. Stem stout or slender, suborbicular. Stamens 6, of 3 fertile and 3 sterile; diffusely branched, branches creeping below, glabrous filaments all equal, bearded. Ovary sessile, 3-cells or sparsely hairy, often coloured, internodes long. each cell 2-ovulate; style naked. Fruits capsule ellipsoid, Leaves sessile, narrowly linear to linear lanceolate, mucronate, the cells 2-seeded, and valves hard. Seeds acute or acuminate, flat, glabrous or hairy; sheath 2 per cell, rough or echinulate, brown and faintly pitted. inflated, ciliate. Inflorescence in cymes reduced to axillary fascicle. Flowers with small linear bracteoles, Cytological Observations almost concealed inthe leaf sheaths; sepals 3, 1. Amischophacelus axillaris (L.) R. Rao et Kamm. (2n spathulate, lanceolate,acuminate; petals 3, pink-blue = 20) or rose purple; filaments fusiform, bearded; style The diploid chromosome number 2n = 20 (PLATE – 1, Fig –1) has been observed in the somatic cells. The detailed Table -1. Karyological features of Amischophacelus axillaris Number of Chromosome length in µm homologous Long Short Total Arm Relative Centro Position of chromosom arm arm length ratio length mere centromer e pairs L/S index e 1 5.0 1.3 6.5 3.8 6.46 20.00 st 2 4.0 1.8 6.0 2.2 5.96 30.00 sm 2 3.8 1.5 5.5 2.5 5.46 27.27 sm 2 2.7 2.3 5.2 1.1 5.16 44.23 m 2 2.5 1.2 3.9 2.0 3.87 30.76 st 1 2.0 0.4 2.6 5.0 2.58 15.38 t Total chromosome length = 100.6 µm Total form percentage = 31.21 Absolute chromosome length = 50.3 µm Total frequency % = 44.84 Average chromosome length = 5.03 µm Disparity index = 266.1 Karyotype formula = 4 m + 8 sm + 6 st + 2t Volume 1; Issue 7; Sep, 2013 Int.J.Curr.Biotechnol. 12 Table – 2. Karyological features of Amischophacelus cucullata Number of Chromosome length in µm Centromere Position of homologous Long Short Total length Arm ratio L/S Relative index centromere chromosome arm arm length pairs 2 4.5 1.5 6.2 3.0 5.98 24.19 st 1 4.0 1.8 6.0 2.2 5.78 30.00 st 3 3.0 1.8 5.0 1.6 4.81 36.00 sm 2 3.0 0.8 4.0 3.7 3.86 20.00 st 2 2.8 0.6 3.6 4.6 3.47 16.66 st 1 2.6 0.4 3.2 6.5 3.08 12.50 t Total chromosome length = 103.6 µm Total form percentage = 25.86 Absolute chromosome length = 51.8 µm Total frequency % = 37.01 Average chromosome length = 4.70 µm Disparity index = 325.68 Karyotype formula = 6m + 14st + 2t karyomorphological features are furnished in the table- noticed.