28. Chromosome pairing in a haploid rice

A triploid plant isolated from a population of diploid Indica variety T 1242, on selfing, yielded a halploid plant which was used in this study. Young spikelets at proper stages were fixed in 1 : 3 acetic alcohol with a trace of ferric chloride and stored in 70% alcohol at low temperature. Slides were prepared by the simple acetocarmine smear technique and were made permanent by n-butyl alcohol method.

Out of 106 pollen mother cells examined at diakinesis, 96 (90.6%) exhibited chromosome association of 8 II + 2 II, followed by 10 I + II (10, 9.4%). None of the PMCs showed 12 I. The consistent synapsis indicates partial homology between the chromosomes. This is in conformity with the earlier observation of haploid rice by Hu (1957, 1960) and also with the report on chromosome association in a triploid rice by Rao and Reddi (1971).

The disjunction at anaphase I was highly irregular. The plant was completely pollen and seed sterile.

Hu, C. H., 1957, Karyological studies of haploid rice plant, 1. The chromosome associations in meiosis. Jpn. J. Genet. 32: 28-36.

-----, 1960. Ditto, IV. Chromosome morphology and intra-genome pairing in haploid plants of Oryza glaberrima, Steud. as compared with those of O. sativa L. Cytologia 25: 437-449.

Rao, G. M. and M. V. Reddi, 1971. Chromosome associations and meiotic behavior of a triploid rice (Oryza sativa L.). Cytologia 36: 509-514.