Genetic characterisation of the petal spot phenotype for Gossypium arboreum accession PI 408798

The occurrence of floral petal spots is common among flowering plants and plays a major role in attracting pollinators. Cotton genotypes having large red petal spots are frequent in the United States Department of Agriculture, National Plant Germplasm System Gossypium arboreum (L.) collection. One accession, PI 408798, showed a unique faint red petal spot phenotype. To genetically characterise this trait, a F₂ population of 226 plants was developed by crossing PI 408798 with G. arboreum accession PI 529714 that lacked pigmented petal spots. From the population, 161 plants showed the presence of faint red petal spots; whereas, 65 plants lacked pigmented petal spots. These data supported the single dominant gene model for the presence of floral petal spots. Accession PI 408798 will provide an important genetic resource to characterise the genes involved in the pathway controlling floral pigmentation.