Genetics of Kidney Seed in Gossypium barbadense L.

The Gossypium barbadense L. germplasm collection contains over 600 accessions listed in The National Collection of Gossypium Germplasm catalog. Kidney cotton, a distinctive type in which the seeds of each locule are conjoined into a single kidney-shaped mass (kidney seed), represent more than 20\\% of the photoperiodic, shortday stocks in the barbadense collection. Several of these kidney cottons are characterized by a complex of traits and are known collectively as G. barbadense var. braziliense (Rafinesque) Fryxell. The objectives of the present study were to determine the inheritance of the kidney seed and its linkage relationships with other Gossypium mutants, and to reexamine the complex of traits associated with var. braziliense. A day-neutral stock with the kidney seed trait was derived from accession K0004 of var. braziliense from Guatemala, and was crossed in appropriate combinations with day neutral, free seed 'Pima S-5' for inheritance studies and with several genetic marker stocks for linkage studies. A survey was made of records of currently available descriptors of accessions of kidney cotton to determine what characteristics were associated with them. Experiments indicated that the kidney seed trait was under genetic control, that it is inherited as a monogenic recessive, and that it is not linked with 21 Gossypium mutant genes. The gene symbol k is assigned to the kidney seed trait. An expanded complex of characters was found to be associated with G. barbadense var. braziliense.