Genetic Mapping of a Locus (hyp) Affecting Seed Hypodermis Color in Sunflower

Sunflower (Helianthus annuus L.) seed color is determined by pigmentation of three layers of the pericarp (hull): epidermis, hypodermis, and phytomelanin layer. A gene with major effects on hypodermis color was reported previously. However, genetic factors that determine the presence or absence of pigment in the hypodermis have not been reported. We identified RFLP markers linked to factor(s) affecting hypodermis pigmentation and assessed the relationship between this trait and oil percentage in sunflower seed. An F 2 single-cross population was produced from homozygous and homogeneous inbred parents ZENB8 and HA89, with pigmented and unpigmented hypodermis, respectively. Two hundred sixty-seven F 2 plants and their F3 families were evaluated. A dominant factor (Hyp) determining the presence of white pigments in the hypodermis was located to linkage group 'G'. Seeds with white hypodermis had lower oil percentage than those with unpigmented hypodermis. The Hyp factor was located in the same map interval as one QTL with major effects on seed oil percentage in this population. Knowledge of genetic linkage among DNA markers, hypodermis pigmentation, and oil percentage should enhance breeding programs.