| Failure of cytokinesis in Secale cereale
D. SINGH, R. P. SHARMA and B. C. JOSHI Division of Genetics, Indian Agricultural Research Institute, New Delhi, India This communication reports the observed failure of cytokinesis in control population of Secale cereale (2n=14). While studying meiosis in cut spikes of Secale cereale, maintained in Hoagland solution for 8 hours at 25C, it was observed that in some of the spikes meiosis proceeded normally up to first metaphase by forming seven bivalents, followed by proper disjunction of homologous chromosomes. However, in other anthers, analysed at first anaphase, the 14 chromosomes were found scattered in the cytoplasm, indicating the failure of cell wall formation between the products of first meiotic division. At the second metaphase the chromosomes had an 'X' shaped morphology. At second anaphase two types of cells were observed, 1) which had 28 chromatids distributed randomly in the cytoplasm and 2) cells in which there were two groups of 14 chromatids each at the two poles. Since diploid rye has 2n=14 chromosomes, the normal execution of different steps of meiosis is expected to give rise to gametes with seven chromosomes each. Realization of microsporocytes with 28 and 14 chromosomes at second anaphase in the present study suggests the failure of cytokinesis at either first or second or both the anaphases of meiotic division. The failure of cytokinesis reported in the present study was observed in spikes from 6 plants out of 10 picked at random from the field and therefore, it is unlikely that mutants for abnormal cytokinesis have been picked up. The failure of cytokinesis therefore, is to be attributed to disturbed metabolic processes incident on excision of the spikes from the plants and subsequent culture conditions to which it had been exposed. The process of meiosis is a very delicately balanced one and a large number of seemingly trivial conditions can upset it. Our observations, therefore, stress the need for a study of adequate controls in experiments done with excised spikes. (Received June 7, 1971) |