Inheritance in Nicotiana tabacum. XI. The Fluted Assemblage

Abstract

The fluted assemblage comprises a series of derivatives obtained directly or indirectly from fluted, a type monosomic for the F-chromosome. Two of these, the recessive types coral and mammoth, are shown to be due to secondary modification of the F-chromosome. Coral and mammoth crossed with normal or with each other, exhibit frequent non-conjunction of the F-chromosomes, as a consequence of which the F2 populations contain haplo-F and trip-lo-F types in addition to the expected classes of offspring. No crossing-over was observed between coral and mammoth. A type called pale sterile also appeared in some lines and was found to owe its sterility to extensive non-conjunction of the chromosomes in meiosis. From pale sterile X normal, variable offspring were produced consisting of monosomic, trisomic and other more complex chromosomal variants. Four instances of origin of carmine-coral variegation are reported; one of which was shown to be due to fragmentation of the F-chromosome and to be subject to reversion to a self-carmine condition. The evidence indicates that coral, and probably also mammoth, is not due to factor mutation; but to some special form of modification to which the F-chromosome is subject when in the univalent condition.