That meiosis is conditioned by a large number of genes majority of which are present in a dominant state, is evidenced by the detection of numerous monogenic recessive mutant genes which affect the premeiotic, meiotic and post-meiotic course of events. These genes are site- and stage-specific, and a few are sex specific. Of these, the most prevalent are the mutant genes affecting male meiosis and causing male sterility (ms genes) and those inhibiting synapsis and chiasma formation (synaptic genes) and leading to gametic sterility. Majority of the mutant genes affect the entire chromosomal complement but a few influence only specific chromosomes of a complement so that the chromosomes behave differentially within a genome of the same species. Some mutant genes alter chromosome form and function, others modify integrity, degree of spiralization, movement and migration of chromosomes. Their cytogenetic behaviour, genetic significance and breeding utility are described and discussed.

This study investigated the technical feasibility of using the tobacco stems biomass (TSB), as a low‐cost novel adsorbent for removal of methylene blue (MB) from water. TSB was characterized by pH zero‐point‐charge (pHZPC) and FTIR analysis. Batch adsorption studies were performed to evaluate process variables, kinetics and equilibrium of MB adsorption. Results showed that MB removal was higher at pH values >pHZPC of adsorbent, and for particle size <0.5 mm. The adsorption kinetics followed pseudo‐second order (k2 = 0.008 to 0.001 g mg−1 min−1), with intraparticle diffusion as one of the rate limiting steps. The Langmuir isotherm with maximum capacity of 169.5 mg g−1 was statistically found a best fit model. A single stage batch adsorber was designed and quantity of TSB required for treating 1000‐10,000 L of stained water was determined. The results imply that the TSB with could be a promising alternative adsorbent for remediation of cationic dye bearing wastewater. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1005–1012, 2017

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Direct somatic embryogenesis is an efficient method of plant regeneration, allowing rapid multiplication of plants in a short period. Six experiments were conducted to study the influence of auxin level on somatic embryogenesis and to optimise the concentration of auxins. Immature embryo axis was the ideal explant and 20–40 mg L–1 of 2,4-dichlorophenoxyacetic acid was the best concentration range for obtaining the maximum number of free somatic embryos. Significant differences were observed between the genotypes for induction and the number of somatic embryos per explant. The cv. Girnar 1 produced the maximum number of somatic embryos per explant, the number of secondary somatic embryos ranging from 1.5 to 9.4. The overall germination of somatic embryos was 42.8%, and 65% of the plantlets transferred to the field survived. The development of somatic embryos was from the apical region of the embryo axes without undergoing dedifferentiation. The initial cell divided to form a tier of four cells and subsequent anticlinal and periclinal division resulted in the development of globular somatic embryos with small suspensors, followed by heart-shaped, torpedo-shaped and ‘cotyledonary’ stages.

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