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Apomixis

Apomixis, one of the challenging area of research even till today. Accationaly (0.01%), we found twin seedlings (two seedlings from a single seed) in rice nursery. We started collecting such rare/abnormal specimens and trying to find out, why is it happening?. Therefore, there was no definite route to approach the problem. This is like questioning the defence machanism or questioning the evolution of rice. We tried to investigate the problem in different directions. Some of the milestones are as below

The above work was the part of M.Sc thesis (Period: 1994– 1996).

Milestones..

Apomixis in rice could be realized morphologically by the occurrence of twin seedlings/multiple seedlings in a single seed. A study was conducted to investigate the occurrence and behaviour of twin/multiple seedlings involving four rice varieties viz., CO45, T3–Basmati, ADT36 and TNAU90627. A range of 4 - 10 seed set was observed in completely emaseculated spikelets in most of the varieties. The progenies of emasculated spikelets showed increased seed set on emasculation, which indicates the enhanced expression of asexual mode of reproduction.

Cytoembryological investigations such as paraffin method of sectioning, pistil cleating, Mayer’s haemalum clearing and fluorescent staining in the pistils’ of all four varieieties revealed the presence of twin ovules and other abnormalities. Isozyme analysis for peroxidase, esterase and polyphenol oxidase on progenies of twin seedlings and their parents was also carried out. Among three enzymes studied peroxidase remained the best index for identifying the asexual mode fo reproduction. Biochemical approach were attempted to investigate the allelic relationship between twins and their parents and among the twins.