Polyploidy or whole genome duplication is an important mechanism for acquiring new genes and creating genetic novelty in plants. In the present study, successful induction of autotetraploidy has been achieved through seedling treatment of colchicine in Cosmos sulphureus. Young seedlings were treated with different concentrations of aqueous colchicine (0.15, 0.2%, each for different durations) using the cotton-swab method. Polyploidy was confirmed during meiotic behavior of pollen mother cells. Induced tetraploid was cytogenetically distinguished from diploid by the occurrence of 48 chromosomes at diakinesis/metaphase-I with different combinations of univalent, bivalents, trivalents, and multivalent. In addition, different types of chromosomal anomalies such as laggards, micronuclei etc. were also observed at anaphase/telophase-I. Various cytological features like chromosomal associations (quadrivalents, bivalents and univalents) and chiasmata frequency were recorded at diakinesis/metaphase-I. It is expected that the induced colchiploid, if established, could be used in further cytological and breeding programs.

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Economically, food industry is one of the fastest growing industries throughout the world generating a high level of competitiveness among producers. Colour of food creates a psychological anticipation for a certain flavour To fulfill the demands of the consumers, the producers add more and more colours to the food to modify its appearance without being concerned about its adverse health effects. The objective of the present study is to evaluate the toxicity of food dyes tartrazine and sunset yellow on the mitotic cells of Trachyspermum ammi (ajwain). Both the dyes were implemented at the four doses viz. 0.5%, 1.0%, 1.5% and 2.0% in the root tip cells of T. ammi. Mitotic indices and chromosomal anomalies were calculated. Frequently observed chromosomal anomalies were stickiness, precocious movement, c-metaphase, bridges, laggards, unorientation and forward movement, etc. The result suggests the genotoxic consequences of two food dyes in the root tip cells of the test system used.

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The genus Mucuna Adans. is represented by 100 species distributed in the world tropics (Lackey 1981; Mabberley 2005). India is one of the natural center of origin of Mucuna. Up to now there are 11 species and three varities of Mucuna reported in India. Mucuna pruriens is useful for medicinally where as Mucuna pruriens var. utilis used for food and fodder purpose (Janardhanan and Lakshmanan 1985; Pugalenthi et al. 2005). Mucuna sanjappae is one of the important medicinal plants since it contains high amount of L-dopamine, which significantly proved as antiparkinson’s drug (Patil et al. 2015). Mucuna macrocarpa is also medicinally important because of its antileukemic effects on human leukemic cells (Kaun-Hung et al. 2012). For the characterization and identification of the proper species the chromosome studies are utmost important. The present work is the first report on karyomorphological analysis of two species of Indian Mucuna viz. M. sanjappae which is endemic to northern Western Ghats, Maharashtra and Mucuna macrocarpa from North-East India. Both the species represented by the chromosome number of 2n = 22. The karyotype formula for M. sanjappae is 11m, while that for M. macrocarpa is 10m + 1M. Total chromosome length in M. sanjappae is 25.15µm while that in M. macrocarpa it is 25.58 µm. Both the species show highly symmetrical karyotype i.e. (1a).

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Effects of heavy metals are very extreme on biological organisms. Pollution causes accumulation of metals in soil which adversely affects the yield attributes of the crop plants. Cuminum cyminum L., (Cumin) is a major spice growing crop of India. The present study has been focused to scrutinize the cytogenetic effects of Chromium (Cr), Cadmium (Cd) and Lead (Pb) on root meristems of Cuminum cyminum L. During experiment, germinated seeds of cumin were exposed to four different concentrations viz., 50ppm, 100ppm, 150ppm and 200ppm of metallic salts of Chromium (Cr₂O₃), Cadmium(CdCl₂) and Lead [Pb(NO₃)₂], respectively. The AMI% (Active Mitotic Index) was observed to show a sharp decline whereas TAB% (Total abnormality percentage) was elevated with increasing metal concentrations. Various Chromosomal aberrations were recorded viz., scattering, stickiness, precocious movement, laggards, bridges, c-metaphase, etc. Among the various types of chromosomal aberrations encountered, stickiness was dominant among all. On comparison Pb was found to be more genotoxic followed by Cd and Cr, respectively.

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The present study aims to determine the impact of gamma radiation on the germination % and mitotic indices in three varieties of Dolichos lablab L. viz. Arkajay, Swarna uthkrishit and RP-08-31, at different doses of gamma rays i.e. 100, 200, 300, 400 and 500 Gy. Through the acquisition of the following experiment, an attempt to screen out the superior variety among the three selected varieties was done for Dolichos lablab. Among the three varieties studied, Arkajay showed the highest germination % and active mitotic index (AMI). A significant decline in AMI and increment in total abnormality percentage (TAB%) was observed with the increase in gamma rays from lower to higher doses. TAB% was induced due to the ionizing radiation. Stickiness, precocious movement, laggard and unorientation were found as preponderant chromosomal abnormalies. However, stickiness was the major abnormality at both metaphase and anaphase stages of cell division. In the present study, variety Arkajay emerged as the best variety based on the fact that it showed highest germination percentage and AMI among all of the three varieties selected.

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