The present study was conducted to genetically characterize a pigment-deficient mutant of sunflower induced by h uitro tissue culture. There's a mutant designed as chlorina-apicarûs. shows pale yellow cotyledons: the first true leaves are initially green, then they become yellow starting from the apex. This phenomenon of photobleaching causes the plantlets to die rn the first stage of development. segregation data from heteràzygous progenies indicate that the trait is controlled by one recessive gene. The symbol ch-ap is proposed for the gene that controls this trait.