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

Authors: Erpelding, John

Submitted to: Czech Journal of Genetics and Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2019
Publication Date: 3/17/2020
Citation: Erpelding, J.E. 2020. Genetic characterization of the petal spot phenotype for Gossypium arboreum accession PI 408798. Czech Journal of Genetics and Plant Breeding. 56:79-83. https://doi.org/10.17221/88/2019-CJGPB.
DOI: https://doi.org/10.17221/88/2019-CJGPB

Interpretive Summary: The dark red spots observed at the base of flower petals in cotton are referred to as petal spots and are important for attracting insect pollinators. Dark red petal spots are frequently observed in flowers of Asiatic cotton varieties (Gossypium arboreum) and these varieties also have red colored stems. There are a few Asiatic cotton varieties in the germplasm collection maintained by the United States Department of Agriculture that lack petal spots and these varieties typically have green stems. During an evaluation of the cotton germplasm collection, one Asiatic cotton variety (PI 408798) was identified that showed faint red petal spots on the flowers and had green stems. To determine the number of genes controlling this usual trait, variety PI 408798 was crossed with Asiatic cotton variety PI 529714 that had flowers with no petal spots and had green stems. The population developed from this cross was evaluated for the presence or absence of petal spots. The majority of the 226 plants evaluated had flowers with faint red petal spots similar to the PI 408798 variety. Analysis of data from the population indicated that the petal spot trait was controlled by a single dominant gene. Color pigment development in plants has several important functions and further research is needed to determine the chromosomal location of the petal spot gene and to evaluate the role this gene plays in pigment synthesis in cotton. Gossypium arboreum variety PI 408798 is a tool that geneticists can use to address these research objectives.

Technical Abstract: The occurrence of floral petal spots is common among flowering plants and plays a major role in attracting pollinators. Cotton genotypes having flowers with large red petal spots are frequent in the United States Department of Agriculture, National Plant Germplasm System Gossypium arboreum collection. One accession, PI 408798, from this collection showed a unique faint red petal spot phenotype. To genetically characterize 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 petal spots similar to the PI 408798 parent; 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 characterize the genes involved in the pathway controlling floral pigmentation.