A Comparative Anatomical Study on the Effects of Mutant Genes on the Pericarp and Seed Coat of Safflower (Carthamus tinctorius L.)

Achenes of safflower (Carthamus tinctorius L.) exhibiting the normal or wild type hull and the mutations for thin-hull (th), brown striped-hull (stp), gray striped-hull (gs), pigmentless (p), and light seed coat (lt) were separately and in various combinations studied anatomically to correlate the external appearance of the hull with its internal anatomy. The hull of the mature normal safflower achene was found to be composed of a pericarp, seed coat, and a one cell layer of endosperm. In studying transverse sections of the hull, the pericarp was found to be made up of two highly sclerified layers separated by a countinuous phytomelanin layer, and the seed coat was composed of a dark brown multiple outer epidermis, a layer of parenchyma cells, and an inner epidermis of crushed cells. The one cell layer of endosperm was centripetal and adnate to the seed coat. Mutations were found to differ from the normal-hull in the degree of thickness, localization of thickness, lignification, and compression of the sclerenchyma layers of the pericarp. They also differed in the absence and localization of the phytomelanin layer, the color of the outer epidermis of the integument, and the degree of thickness of the parenchymous layer of the integument.