Seed coat rupture and endosperm protrusion in developing seeds of Catharanthus roseus (L.) G. Don.

Abstract

SummaryProtrusion of the endosperm due to rupture of the seed coat that occurs during seed formation in Catharanthus roseus (L.) G. Don was investigated. Rupture was not limited to a specific part of the seed coat. It occurred most frequently at the chalazal end of the seed. Seeds with protruding endosperm were formed in fruit 17 d after pollination, or later, when the endosperm filled the space enclosed by the seed coat. The frequency of seeds with protruding endosperm increased with the stage of physiological maturity. Seeds with protruding endosperm comprised up to 12% of seeds harvested at full maturity. The protruding endosperm was composed of an abnormal proliferation of endosperm cells. In seeds with protruding endosperm, the seed coat was poorly developed and the embryo protruded from a rupture in the seed coat after imbibition. The percentages of seeds that germinated normally were 61% and 15%, for normal seeds and seeds with a protruding endosperm, respectively. Protrusion of the endosperm in C. roseus seeds may have been caused by a thin seed coat and by pressure caused by the developing embryo and endosperm.