Inheritance of spininess and flower color in safflower (Carthamus tinctorius L.)

Abstract

In safflower, spininess and flower color are key heritable traits widely used as reliable morphological and phenotypic markers in breeding programs. This study aimed to elucidate the mode of inheritance and the number of genes controlling spininess and flower color by analyzing segregation patterns in the F₁ and F₂ generations derived from a cross between two contrasting parental varieties, ‘Dinçer 5-18-1’ (spineless with red flowers) and ‘Olas’ (spiny with yellow flowers). Flower color and the presence or absence of spines on leaves and bracts were recorded at the end of the flowering stage for F₁ hybrids and individual F₂ plants. Phenotypic segregation ratios in the F₂ population were evaluated using the chi-square (χ²) test. Segregation analysis in the F₂ population showed with spininess fitting a 3:1 segregation model, indicating that the spiny phenotype is controlled by a single dominant gene over spinelessness. Flower color segregation conformed to a 9:3:4 ratio, where yellow was dominant in the F₁ generation, and the F₂ population segregated into yellow, orange, and red phenotypes due to recessive epistasis between two loci, with the homozygous recessive condition masking the expression of the second gene. This study shows that spininess in safflower is inherited as a simple monogenic trait with complete dominance, flower color is controlled by the interaction of multiple genes showing both dominant and recessive epistatic effects between extra-allelic loci.