Summary
In theF 2 of a cross between two American Upland (G. hirsutum) types, Uganda B31 and the Sudan variety 514, a number of markedly dwarfed, ‘bunched-up’ plants appeared. Investigation showed that normality as opposed to ‘Dwarf-bunched’ depends on the presence of either of two duplicate genes, one dominant and the other giving an intermediate heterozygote. These genes have been calledD a andD b , the former deriving from 514 and the latter from Uganda B31. 514 is ofD a D a d b d b genotype, Uganda B31 isd a d a D b D b , Dwarf-bunched isd a d a d b d b , and the heterozygoted a d a D b d b shows considerable variability with a range from dwarf to normal.
The gened b occurs in Gambia Native (G. hirsutum var.punctatum) and in the American Upland varieties Uganda SP84, XA129 and Deltapine, but it was not present in all Upland varieties examined.
The gened a is closely linked with (or possibly identical with) the blackarm-resistance geneB 1. SinceG. barbadense types are ofD a D a D b D b composition,B 1 can be utilized in conferring blackarm resistance on this group. Its use within, theG. hirsutum group is fraught with the danger of producing, Dwarf-bunched types as the end-product.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Fisher, R. A. (1930).The Genetical Theory of Natural Selection. Oxford University Press.
Knight, R. L. &Clouston, T. W. (1939). The genetics of blackarm resistance. I.J. Genet. 38, 133–59.
Knight, R. L. &Clouston, T. W. (1941). The genetics of blackarm resistance. II and III.J. Genet. 41, 391–409.
Tothill, J. D. (Editor) (1940).Agriculture in Uganda. Oxford University Press.
Author information
Authors and Affiliations
Additional information
(With Plate 5)
Rights and permissions
About this article
Cite this article
Knight, R.L. The genetics of blackarm resistance. Journ. of Genetics 48, 43–50 (1947). https://doi.org/10.1007/BF02986096
Issue Date:
DOI: https://doi.org/10.1007/BF02986096