Inheritance of a Fertility Enhancer Factor from Pima Cotton when Transferred into Upland Cotton with Gossypium Harknessii Brandegee Cytoplasm1
- R. H. Sheetz and
- J. B. Weaver2
Present efforts towards the development of hybrid cotton in the United States are concentrated almost exclusively on the use of Gossypium harknessii Brandegee derived cytoplasmic male sterility. Fertility restoration is controlled by an incompletely dominant gene, leading to variable fertility in heterozygous F1 upland ✕ upland hybrid populations. However, G. barbadense L. apparently possesses a modifying gene(s) which enhances fertility expression when present in upland cytoplasmic malesterile ✕ upland restorer F1 hybrids.
Self-pollinated seed, derived from a cross of male-fertile plants of G. hirsutum L. in G. harknessii cytoplasm ✕ ‘Pima S-4’ (G. barbademe), followed by three backcrosses to non-restoring upland strains was planted in progeny rows in 1977. Individual fertile plants were selfed and testcrossed to six G. harknessii-derived cytoplasmic male-sterile strains to determine inheritance of the Pima enhancer factor. Testcrossed and selfed seed were planted in individual progeny rows in 1978 and segregation ratios analyzed.
Analysis of progenies showed that male fertility restoration in F1 G. hirsutum hybrids in G. harknessii cytoplasm is enhanced by adding a genetic factor from the G. barbadense genome. Fertility in hybrid populations heterozygous for the restorer gene which possess the enhancer factor is comparable, if not superior, to that of the homozygous restorer lines which do not have the enhancer factor.
Data strongly indicate that the enhancer factor derived from G. barbadense is controlled by a single gene expressing dominance. However, there is some indication that the enhancer may, in some instances at least, express incomplete dominance. The symbol E is proposed to denote the G. barbadense gene for fertility enhancement.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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