Complications in Breeding for Incompatibility

C. Rhyne and J. Carter


 
ABSTRACT

Were genes for compatibility and tufting seed-coverage associated when stocks were developed from the tufted, naked-seeded Gossypium barbadense L. donor ? The amount of seed covering is more abundant than in the original compatible. Incompatibles have Le(2)( dav) from donor G. davidsoni introduced into a compatible stock and some what greater amounts of seed fuzz. Cultivars are lethal when crossed with incompatibles; those of G. hirsutum L. have seed covered completely by fuzz and tufted G.barbadense must have seed with a minimum of fuzz. Penetrance and expressivity of genes from donor G.barbadense varied in studies of Stoneville 907 Cv and compatible stocks. Despite altered penetrance and changeable expressivity, these studies showed a gene different from N(1) naked seed and recessive n(1) fuzzy. Tufting and nectary expression were associated. Seed covering conformed to the ratio 9 tufted to 7 fuzzy. One gene of tufting was associated with Ne(1) nectary, showing 20.5 cM + 4.2 cM recombination. Replacement of n(1) of 907 Cv for N(1) as le(1) n(1) recombination of 2.6 cM resulted in a change from tufted to fuzzy seed in the testcross with the incompatible testor. This gene for tufting in compatible and incompatibles appears to be ordered Gl(2) le(1) n(tf) Ne(1) Ms(8). Compatible 907 Cv would have genes of hirsutum except for le(1) of G.barbadense replacing Le(1) and ne(1) of G.tomentosum for the nectariless version.



Reprinted from 1995 Proceedings Beltwide Cotton Conference pp. 536 - 538
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998