Cytogenetical analysis of Clitoria ternatea

Clitoria ternatea L. of the family Fabaceae is an economical, ornamental as well as medicinal important species. Chromosome characterization of C. ternatea, encompassing karyomorphological as well as fluorochrome binding was carried out in the present investigation. Karyomorphological studies showed the presence of 2n = 16 somatic chromosome number with three pairs of metacentric chromosomes and five pairs of submedian chromosomes. The analysis also revealed the present of one pair of nucleolar organizing region or satellite. Fluorochrome binding using chromomycin A3 (CMA) and 4-6-diamidino-2-phenylindole (DAPI) showed the presence of GC- and AT- rich heterochromatic region. Further analysis revealed the percentage of GC-rich was comparatively higher than AT-rich heterochromatic region. This is the first report on heterochromatin characterization in C. ternatea.

Diversity and cytological studies of the Genus Amomum Roxb. former Elettariopsis Baker (Zingiberaceae) in Thailand

Saensouk P, Saensouk S. 2021. Diversity and cytological studies on the genus Amomum Roxb. former Elettariopsis Baker (Zingiberaceae) in Thailand. Biodiversitas 22: 3209-3218. A comprehensive diversity and cytological studies of the genus Amomum Roxb. in Thailand have not been reported. This work aims to study the diversity and cytological including chromosome numbers and karyotypes of the genus Amomum Roxb. former Elettariopsis Bakerin Thailand. Ten species of Amomum were recognized from Thailand. Nomenclatures, vernacular names, distribution, ecology, and traditional utilization are provided. Only Amomum wandokthong is widely cultivated in all parts in Thailand. Four living species, i.e. Amomum curtisii, A. monophyllum, A. trilobum, and A. wandokthong have been collected from field trips. Therefore, the somatic chromosome numbers from four species of this genus were studied from root tips. The somatic chromosome numbers of each species in this study were counted from 20 cells. The karyotype formulas were derived from measurements of the metaphase chromosomes in photomicrographs. The chromosome numbers of four species were found to be 2n = 48. Karyotypes of four species were reported to be Amomum curtisii (32m + 8sm + 8st), A. monophyllum (26m + 12sm + 10st), A. trilobum (18m + 24sm + 6st), and A. wandokthong (28m + 16sm + 4st with five visible satellites chromosomes). The chromosome numbers of A. monophyllum and A. wandokthong were reported for the first time. The karyotypes of four species were studied for the first time.

Karyomorphology, Meiotic Behaviours and Pollen Fertility of Calendula officinalis L. (Calenduleae- Asteraceae)

The present study includes chromosome number, karyomorphology, meiotic behaviors and pollen fertility of the species Calendula officinalis L.collected from central Nepal was cytologically carried out using two percent aceto-orcein for somatic chromosome determination and one percent aceto-carmine for meiotic study. Pollen fertility was based on stainability test using Muntzing solution. Somatic chromosome number determined for this taxon were 2n=28, haploid chromosome number n=14 and pollen fertility found to be 84.4 percent in the present study. In karyotype analysis chromosome length ranged from 0.4 to 2.6 µm and mean length was 1.5 µm. Likewise, absolute length found to be 21.9 µm and karyotype formula obtained was M16+m4+ sm8. Three types of chromosomes centromere at middle point, at median region and at sub –median region were observed. Meiosis with regular and irregular behaviors was observed in this study. The variations in chromosome numbers, irregularities in meiotic behaviors, variations in karyomorphological structure and high fertility rate shows evolve nature of this species which play a great role in evolution. Pollen fertility was also affected by meiotic abnormalities. Int. J. Appl. Sci. Biotechnol. Vol 9(1): 75-79

Cytogenetic studies of three cultivated hill cotton (Gossypium arboreum L.) varieties from Bangladesh

Three hill cotton (Gossypium arboreum L.) varieties viz., HC-1, HC-2 and HC-3, released by Bangladesh Cotton Development Board were investigated through orcein, CMAand DAPI-banding for cytogenetical characterization and to elucidate the karyotypic diversity among these varieties. All these three varieties were found to possess 2n = 26 metacentric chromosomes with ‘1A’ karyotype. Based on TF%, AsK% and Syi index, HC-3 was little advanced over HC-1 and HC-2. These three varieties showed differential Chromomycin A3 (CMA)- and 4Ê-6 Diamidino-2-Phenyl Indole (DAPI)-banding patterns and a tendency of acumulation of repetitive sequences at the terminal regions was observed. Despite possessing same somatic chromosome number these three hill cotton varieties could be characterized by diversified karyotypic parameters through differential staining.

Karyomorphology of Two Species of the Genus Spilanthes (Heliantheae-Asteraceae)

In present investigation karyotype of mitotic chromosomes were determined, two species of the genus Spilanthes, namely Spilanthes acmella (L.) Murray and Spilanthes calva DC. from plants transplanted in earthen pots collected from different localities from Central Nepal in my home garden. The somatic chromosome number determined in present study were 2n=36 for both species, Spilanthes acmella (L.) Murray and Spilanthes calva DC. The chromosomes total length ranged from 0.6 to 1.6 µm in Spilanthes acmella (L.) Murray and 0.4 to 2.1µm in Spilanthes calva DC. The relative length ranged from 2.3 to 12.1 µm in the species Spilanthes calva and 2.0 to 8.5 µm in the species Spilanthes acmella. The Karyotype formula were M16+m2+sm16+st2 in Spilanthes calva DC. and M22 +sm14 in Spilanthes acmella (L.) Murray cytologically obtained by using 2% aceto-orcein. The karyotype of the two species shows considerable variation exists in morphology of chromosome and structure. The variation in karyomorphology shows evolved nature of this species which play a great role in evolution. Int. J. Appl. Sci. Biotechnol. Vol 8(4): 422-426

Polyploidy in the Ginger Family from Thailand

Polyploidy is common in the ginger family Zingiberaceae. The aims of the present paper are (1) to provide a general introduction on species diversity with emphasis on conservation; (2) to highlight the human-use significance of this family, focusing on the two major genera, Zingiber (ginger) and Curcuma (turmeric); (3) to present chromosome number data from 45 natural and cultivated Curcuma taxa from Thailand, of which polyploids are predominant; and (4) to describe our own work on cytotaxonomy of selected Thai Curcuma species. We obtained somatic chromosome numbers from root tips and analysed meiotic chromosome behaviour from flowers. We also used the molecular cytogenetic method of ribosomal gene mapping on chromosomes to infer mechanism of polyploidization and reveal genomic relationships among closely related species. The main results of our cytogenetic studies include the following. The most sought-after medicinal Curcuma cultivars growing on a large-scale basis are secondary triploids, so as taxa in natural habitats that are harvested for local utilisation. These triploids are sexually deficient, due to meiotic pairing abnormalities, but they are propagated asexually via rhizomes. The ribosomal mapping results indicate natural triploidization process via hybridisation, either within populations or across the species boundaries.

Interphase nuclear phenotype and chromosomal variation in Cynodon dactylon (L.) pers

Interphase nuclear phenotype in different accessions (Acc.) of Cynodon dactylon studied in the present experiment showed chromocentric nuclear organization and the chromocenters were found to be visible clearly. The chromocenter numbers were not same and sometimes it was found to be significantly less and never more than total number of chromosomes. Percentages of heterochromatin values were expressed per nuclear area and the values range from 19.759% (Acc. 16) to 66.022% (Acc.18). Nuclear volume as well as interphase chromosome volume was found to vary 0.674 μm3 (Acc.6) to 41.921 μm3 (Acc.10) and from 0.028 μm3 (Acc. 6) to 1.905 μm3 (Acc. 10), respectively. The somatic chromosome number found to vary from 12 to 40. 2n = 18 chromosomes were found in eight accessions of C. dactylon. Only one accession was found to be tetraploid and rest of them aneuploid whose chromosome numbers were 12, 14, 16, 22, 24, 26, 32, 40 etc. The availability of aneuploid shows great aspects of forage breeding programme. J. bio-sci. 27: 133-141, 2019

Chromosome numbers, RAPD and ISSR profiles of six Zingiber species found in Manipur, India

Bidyaleima L, Kishor R, Sharma GJ. 2019. Chromosome numbers, RAPD and ISSR profiles of six Zingiber species found in Manipur, India. Biodiversitas 20: 1389-1397. The present investigation was done to assess the cytological information and genetic relationships among six species of Zingiber, viz., Zingiber capitatum, Z. kangleipakense, Z. kerrii, Z. montanum, Z. officinale and Z. zerumbet found in Manipur, North-East India. The somatic chromosome numbers observed were 2n = 22 for Zingiber capitatum, Z. kerrii, Z. montanum, Z. officinale and Z. zerumbet, whereas Z. kangleipakense showed tetraploidy with 2n = 44. The somatic chromosome numbers of Zingiber kangleipakense and Z. kerrii are reported for the first time. Randomly amplified polymorphic DNA (RAPD) and inter-specific sequence repeat (ISSR) molecular markers were employed to reveal the genetic relationships among the six species. The pair-wise Jaccard genetic similarity varied from 0.518 to 0.658 for RAPD and from 0.436 to 0.682 for ISSR data. Dendrogram derived from the combined data of RAPD and ISSR clustered the six members into two groups. The detected polymorphism level represents high genetic distance at the inter-species level, and introduces RAPD and ISSR as efficient markers for the assessment of genetic relatedness in Zingiber. Our results may provide useful information for application in breeding, conservation and utilization.

A report on new chromosome number of three Dioscorea species

Chromosomal study conducted in nine species of Dioscorea from different forest belts of Tripura revealed that their somatic chromosome number ranged from 2n=40 to 2n=60. The record of 2n=40 chromosome in the sexual phenotypes of Dioscorea hamiltonii, Dioscorea glabra and Dioscorea pubera are the first time report from Tripura, North East India. Moreover the somatic chromosome counts of 2n=60 in Dioscorea pentaphylla would be attributed as a new cytotype. However at the respective ploidy level no difference in somatic chromosome count was observed between their sexes.

Morphological, cytological, palynological and molecular evidence on two new hybrids from Turkey: an example of homoploid hybridization in Origanum (Lamiaceae)

Two new hybrids of Origanum, O. ×malyeri and O. ×sevcaniae, are described and illustrated in detail. The general morphology, pollen and chromosome features, and nuclear (ITS) and chloroplast (rpl32) genomes of collected specimens were studied. Origanum ×malyeri is a hybrid between O. boissieri and O. vulgare subsp. hirtum and O. ×sevcaniae is another hybrid between O. vulgare subsp. hirtum and O. vogelii. These two new hybrids have some morphological intermediate characters between their parents. The pollen morphology of O. ×sevcaniae and its parents were studied and documented in detail using light microscopy (LM) and scanning electron microscopy (SEM). O. ×sevcaniae pollen is small to medium (P=18.49–21.03 µm, E=22.20–26.63 µm), suboblate (73%) to oblate (22%), the range of P/E ratio is from 0.73 to 0.85. Pollen grains are hexacolpate with granular membranes. Pollen grains were identified as bireticulate exine ornamentation with scanning electron microscopy examinations. The somatic chromosome number of O. boissieri, O. vulgare subsp. hirtum, O. vogelii, and O. ×sevcaniae were counted as 2n = 30. Pollen characters and somatic chromosome numbers of O. ×malyeri could not be examined because it has only female flowers and has not any nutlets. Also, according to molecular results, O. ×malyeri and O. ×sevcaniae have some polymorphic nucleotide regions in their nuclear ITS genomes and which means they have two different DNA dataset belonging to their parents. Also, some individuals of O. ×sevcaniae parents have single nucleotide polymorphism, too. These individuals live together with their hybrids and hybridization is probably a continuing process in that hybrid swarms. These present results support previous reports for the speciation of Origanum members via hybridization.