II. 23. Induced asynapsis in barley.
G. Prasad*, S.N. Mathur**, and D.K. Tripathi*. *Department of Agricultural Botany, S.D.J. Post Graduate College Chandesar, Azamgarh (U.P.) 276128; and ** Gorakhpur University, Gorakhpur, India. "R"
An asynapsis mutant was isolated from the M2 generation of seeds of barley cultivar DL 36 treated with 0.3 per cent diethylsulphate (DES). No pairing of homologous chromosomes was observed at Pachytene, indicating complete asynapsis. There was the presence of 14 univalents at diakinesis (Fig. 1) and metaphase I. In 18.5 per cent of the metaphse I cells, the univalents were scattered while in rest of the cells they were polar with unequal distribution ranging from 0 to 14 towards each pole. In most of the cases, there were unequal segregations at anaphase I, leading to the formation of spores of unequal size (Fig. 2). Multipolar separations were also observed with considerable frequencies.
Fig. 1. Diakinesis showing 14 univalents.
Fig. 2. Tetrad showing unequal size of microspores.
In barley, induced desynapsis of varying degrees has been reported by Enns and Larter (1960), Sharma and Reinbergs (1974), Srivastava (1974) and others. However, to the authors' knowledge, this may be the first report of complete asynapsis in barley induced through chemical mutagen.
Enns, H. and E.N. Larter. 1960. Note on inheritance of Ds; A gene governing meiotic chromosome behavior in barley. Can. J. Plant Sci.
Sharma, R.K. and E. Reinbergs. 1974. Cytogenetic analysis of a desynaptic mutant in barley (Hordeum vulgare L.). Cytologia 39:77-81.
Srivastava, H.M. 1974. Radiation induced desynaptic mutants in barley. Cytologia 39:63-68.
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