THE ANTHER TAPETUM IN CYTOPLASMIC‐GENETIC MALE STERILE SORGHUM

Abstract

Measurements of anthers of five fertile lines of Sorghum vulgare Pers. indicate that the tapetum decreases in radial extent following the two‐celled dyad stage of meiosis. At a mature pollen stage 78% of the anthers of fertile lines and 88% of those of a fertility restorer line have a narrow tapetum measuring between 4 and 16 μ radially, with the remainder having a degenerate tapetum less than 4 μ wide. In isogenic sterile lines, approximately 68% of the anthers have a narrow tapetum less than 16 μ wide at a “prepollen” stage, which represents the terminal stage in the sterile lines, whereas the remaining 32% have a well‐developed or enlarged tapetum measuring over 28 μ in radial width. Tapeta in the sterile lines have a variation in width and in morphology not encountered in fertile lines and presumably display the variable manifestations of nuclear‐cytoplasmic interaction characteristic of cytoplasmic‐genetic male sterility.