The Association of a Single B‐chromosome With Male Sterility in Plantago Coronopus

Paliwal, Ripsudan L. (B. R. College, Agra, India.), and Beal B. Hyde. The association of a single B‐chromosome with male sterility in Plantago coronopus. Amer. Jour. Bot. 46(6): 460–466. Illus. 1959.—Two species of Plantago showing male sterility have been studied cytogenetically. In P. ovata (n=4) the sterility appears to be cytoplasmic. In P. coronopus (n=5) all male‐sterile plants contain a single extra chromosome which is largely heterochromatic, shorter, and not homologous with any of the other chromosomes. No male‐fertile plants contain this B‐chromosome. Meiosis is regular in the male‐sterile lines. The accessory chromosome usually does not divide and moves to one pole at the first division of meiosis and divides regularly in the second division. Degeneration of all microspores occurs before pollen mitosis. Male‐sterile plants are apomictic, but whether or not male‐fertile plants are also apomictic has not yet been determined.