Document Type

Thesis - Open Access

Award Date

1961

Degree Name

Master of Science (MS)

Department

Agronomy

Abstract

Diploid mutant shoots having the characteristics of inbreds have arisen from colchicine-tumors induced on highly inbred varieties of Sorgum vulgare Pers. To produce C-tumors, colchicine-in-lanolin was applied to the coleoptiles just emerging from the seed coat during germination. If the occurrence of somatic reduction were preceded by mutation and followed by restoration to the diploid number, a resulting homozygous, diploid mutant cell in an advantageous position, competitively and/or spatially, could assume leadership in the apex of the growing point of the shoot. According to this hypothesis, chromosomal markets heterozygous in plant embryos preliminary to colchicine treatment would be homozygous in cells in some shoots arising from the colchicine-induced tumors. Therefore, if mutations were induced within colchicine tumors on plants originally homozygous for all but a few genes, but carrying a heterozygous chromosomal marker such as a translocation or inversion, and if subsequent shoots emerging from this tumor were indentified as homozygous for genes originally heterozygous, for mutations, and for the chromosomal marker, a somatic reduction would likely have taken place. As no chromosomal markers such as reciprocal translocations or inversions were available in sorghum lines producing true-breeding diploid mutants after colchicine treatment, the problem described here is primarily that of inducing such chromosomal markers in the reactive lines. To obtain chromosomal markers such as translocations and to study the effects of gamma irradiation from a Co60 source, Experiemntal 3 plant material was irradiated at two stages, one, the somatic cells in the seed, seedling or C-tumor-seedling stage and the other, the gametes at preanthesis.

Library of Congress Subject Headings

Sorghum
Cytogenetics
Colchicine

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

157

Publisher

South Dakota State University

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