Three genetic systems are operative in plants, the nuclear, the mitochondrial and the chloroplastic. The later two are always inherited from the maternal parent in cotton and in most (but not all) other plants. The organelles are intimately involved in the energy relations of the plant in their functional roles of photosynthesis and respiration. Because of this we can reasonably expert that the cytoplasm of a plant will have a strong influence on the performance of that plant. Several of the protein complexes involved in these activities contain subunits that are synthesized in the organelle from genetic information carried in that organelle. other subunits of the same complex are inherited through the nucleus via normal recombination of male and female parent. The three systems must be tightly regulated and function in concert for the plan to perform at an optimum level.

To generate diversity in the genetics of this interaction, isogeneic, alloplasmic lines of cotton have been developed. The alloplasms include the cytoplasmic or maternal inheritance of Gossypium hirsutum, G. barbadense, g. sturtianum, G. harknessii, G. davidsonii, G. trilobum, and G. longicalyx. Each of the cytoplasns were introgressed into a G. barbadense nuclear background containing the semigamy trait. Doubled haploid lines of G. barbadense and G. hirsutum were then used as pollen donors to extract isogeneic haploids via expression of the semigamy.

In these lines, the nuclear component is held constant (isogeneic) while the cytoplasmic component is varied. The lines have potential use in research on maternal inheritance and the interaction between the nucleus and cytoplasm in control of genetic expression in the mitochondria and chloroplast. They should be useful tools to examine the regulation of photosynthesis and respiration. in addition to the interactions one expects to find in the energy complexes of the alloplasms, one interesting feature that shows up frequently is cytoplasmic male sterility. This occurs in several of the lines.