Somatic Reduction and Chromosome Elimination,Reductional Mitosis,Swaminathan,Singh,South Dakota State University,Sorghum Vulgare,para fluorophenylalanine(PFPA)

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	Somatic Reduction and Chromosome Elimination - Cases are known where either spontaneously or due to specific treatments, the chromosome number was reduced to half in the somatic tissues, a phenomenon described as somatic reduction or reductional mitosis. Swaminathan and Singh (1958) induced a haploid branch on a watermelon by irradiation of the seed used. This must have resulted by the reduction of chromosome number in the somatic tissue through an unknown mechanism (perhaps due to spindle organizer abnormalities).
Similarly, colchicine treatment has also been found to lead to the reduction in chromosome number. Franzke and his associates at South Dakota State University conducted a series of interesting studies in Sorghum vulgare. They found that in Sorghum vulgare, somatic tetraploid (2n = 4x) cells responded to colchicine treatment and gave rise to diploid cells, which took over the growing point completely thus giving rise to diploid individuals. In general, attempts to induce somatic reduction in other species by treating seeds or seedlings with colchicine have failed or met with only partial success as in flax (Dirks et al., 1956). There are also a number of other chemicals like chloramphenicol and para fluorophenylalanine (PFPA, an amino acid analogue) which have sometimes been successfully used for production of haploids in a number of materials.