On the basis of recombination frequencies in relation to the centromere the placement of these genes is shown below -
All these genes are located in a gene order of Red grain colour (3.30) - Spherical grain (very closed to red grain) - Short spike (5.44) - and Short peduncle (10.58) within a map unit of 21.17 from the centromere.
Another significant finding observed in the present study was the occurrence of plants with white seeds in the F2 population of these two red seeded varieties. Plants with white seeds are not expected if the gene (R1) which controls the red seed colour in these varieties is at the same locus. Occurrence of plants with white seeds but with low frequency (3.3%) clearly shows that the genes which control red colour of seeds in vars. Chinese Spring and T. sphaerococcum are not situated at the same locus.
Acknowledgment
The author is grateful to Dr. B. C. JOSHI of Biotechnology Centre, Indian Agricultural Research Institute, New Delhi, India, for critical reading of the manuscript.
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