SummaryThe 3 forms of Colocasia fallax Schott. complex, namely green petiole form, light purple petiole form and deep purple petiole form, available in Bangladesh were studied cytogenetically to confirm their taxonomic status after staining with orcein and CMA. The green petiole form and the deep purple petiole form were found to possess 2nϭ28 chromosomes whereas 2nϭ30 chromosomes were observed in the light purple petiole form. The centromeric formula was determined as 20 mϩ8 sm in the green petiole form, 26 mϩ2 smϩ2 ac in the light purple petiole form and 24 mϩ4 sm in the deep purple petiole form. Acrocentric chromosomes were found only in the light purple petiole form. 4 satellites were found in the green petiole form after orcein staining while only 1 satellite observed in CMA staining of the same form. These satellites showed stain specific nature in this form. 8 and 11 CMA positive bands were found in the green petiole form and the deep purple petiole form, respectively. Only 2 centromeric CMA positive bands were found in the light purple petiole form. Different CMA banding pattern and percentage of GC-rich repeats were found in these 3 forms. CMA banding was able to identify some chromosomes in the green petiole form and the deep purple petiole form. The diploid chromosome numbers and overall karyotypic features indicated that the light purple petiole form possessed quite different genomes than the other 2 forms and thus may be placed in a different taxonomic rank. Except a minute difference in the karyotypic features, the green petiole form and the deep purple petiole form possessed almost entirely similar genomes and therefore could be considered as different varieties of Colocasia fallax.

Three Asparagus species viz. A. racemosus Willd., A. officinalis L., and A. setaceus (Kunth) Jessop were investigated by cytogenetical and molecular analysis for authentic characterization. The diploid chromosome number 2n=20 was found in A. racemosus and A. setaceus, while, A. officinalis possesses 2n=22 chromosomes. Diploid chromosome number 2n= 22 is the first report for A. officinalis. These three species differed in respect of other karyotypic features such as total length of 2n chromosome complements, number of satellites, range of relative lengths, centromeric indices, etc. Some unique CMA-and DAPI-banded chromosomes were found in three species which could be used as marker chromosomes for the respective species. A pair of satellites was observed in A. racemosus after CMA-and DAPI-staining but absent in orcein staining indicating the stain-specific nature of satellites. The chromosomes of three Asparagus species possessed different structural abnormalities such as deletions, tandem duplications, and dispersed distribution of GC-and AT-rich repetitive sequences. This organizational variation of chromosomes was one of the major reasons for karyotype diversification. Four primer combinations were applied for RAPD analysis in three species of Asparagus to find out their genomic relationship. The three species showed several unique bands useful as markers for each species. Therefore, the three Asparagus species could authentically be characterized by conventional and fluorescent karyotype together with RAPD fingerprinting.

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In the present study, micromorphology and comparative anatomy of young root, stem and leaf of three economically important taxa of Brassica L. viz., B. rapa L. subsp. campestris (L.) Clapham, B. juncea (L.) Czern. and B. napus L. are investigated in detail for the first time in Bangladesh by using light microscopy (LM). In anatomical studies, cross sections of young root, stem and leaf have been examined and biometric measurement of cell and tissues are presented. The micromorphological studies are related to the epidermal surface. In addition, the stomatal index and stomatal index ratio of these taxa have been calculated and presence of simple, non-glandular, unicellular trichome on stems and leaves also been observed except on the stem of B. rapa L. subsp. campestris (L.) Clapham. The anatomical study reveals that the investigated taxa have primary growth in roots and stems as well as amphistomatic and bifacial leaves with anisocytic stomata have been noticed. Finally, presence of tetrarch or single strand exarch xylem in vascular bundle of root, the size, shape and presence or absence of trichome over stem, shape of midrib of leaf have been considered to provide reliable features for identification of the Brassica species. Bangladesh J. Plant Taxon. 27(1): 15-26, 2020 (June)

Summary Nine varieties of Cicer arietinum L. (chickpea) released by Bangladesh Agriculture Research Institute (BARI), viz. BC-1 (BARI Chola-1), BC-2, BC-3, BC-4, BC-5, BC-6, BC-7, BC-8 and BC-9, represented a broad spectrum of variation for several phenotypic and agronomic traits. For authentic characterization, these varieties were investigated cytogenetically by differential fluorescent banding. The nine chickpea varieties were found to possess 2n=16 metacentric chromosomes. A wide range of CMA-positive bands (5-20) was found in the metaphase chromosomes of the nine varieties. Two satellites were found in the first pair of only BC-2, BC-3, BC-4, BC-6, BC-8 and BC-9 after DAPI-staining. No satellite was found after CMA-staining. The differential staining property of satellites revealed the stain specific nature of these satellites. Entirely DAPI-fluoresced chromosomes were frequent in these varieties. The number, location and distributions of GC-and AT-rich repeats are specific for each variety. Some CMA-and DAPI-bands were so unique that these chromosomes could easily be used as marker chromosomes for the respective varieties. Fluorescent banding revealed the occurrence of genomic alteration within these varieties. Therefore, each variety could be characterized authentically by fluorescent banding analysis.

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Costus spicatus (Jacq.) Sw. is a species of Costaceae (Zingiberaceae) family, which is most familiar as a medicinal plant because of its therapeutic values. A detailed karyological analysis has been accomplished through aceto-orcein staining, chromosome number was reported 2n=18 along with the presence of one Bchromosome, which exhibited with a karyotype formula as 16m+2sm. It would be a new report for C. spicatus. The esteems of various karyomorphological indices regarding the aspect of asymmetry, demonstrated its symmetry in the karyotype. Therefore, the basic chromosomal information of the current investigation will contribute to deposit chromosomal knowledge and conservation of plant genetic resources of C. spicatus as an invaluable medicinal plant.

Four specimens of Gynura nepalensis DC. were investigated for authentic characterization by differential cytogenetical and PCR based molecular analysis. Three specimens out of four were collected from different localities of Bangladesh viz. i) from Netrokona district (specimen A), ii) from Dhaka district (specimen B) and iii) from Bogra district (specimen D). On the other hand, specimen C was collected from Canada. The diploid chromosome number of four specimens were 2n=20 with different centromeric formulae such as 14m+6sm in specimens A, B and D while 20m in specimen C. Total length of 2n chromosome complement was 211.61 µm in specimen A, 217.58 µm in specimen B, 168.82 µm in specimen C and 197.80 µm in specimen D. The maximum range of chromosome length was found in specimen B (6.67-14.30 µm) and minimum in specimen C (6.44-10.12 µm). The four specimens have distinct CMA-and DAPI-banding pattern which confined to the terminal regions of respective chromosomes. Karyotype analysis revealed that the number, location and distributions of GC-and AT-rich repeats are different in these four specimens. Heteromorphicity in respect of occurrence of CMA-and DAPI-banding pattern in the homologue members were observed in specimen A, C and D. The heteromorphicity might be a result of deletion of banded region from the respective homologue members. One interstitial CMA band was found on the short arm in a member of pair V in specimen A and in pair IV of specimen C. Two terminal DAPI bands were found in two chromosomes of specimens A and B. These CMA-and DAPI-banded chromosomes were unique and thus could be used as marker chromosomes for the respective specimens. Only specimen C showed RAPD bands with three primers. However, the four specimens had distinguishable ISSR-banding patterns with seven primer combinations. Specimen C showed maximum ISSR bands. The combined RAPD and ISSR analysis placed specimen C in a separate cluster with the highest genetic distance. In spite of very distant location specimens A and D were placed in a sub-cluster with narrow genetic distance.