Causes of Partial Male Sterility in an Inbred Maize Line.

The causes of partial male sterility were studied in an inbred maize line. Meiotic analysis revealed a high frequency of countless irregularities. Particularly outstanding among them were univalent chromosomes, irregular segregation at meiosis I and II, micronuclei, chromosome breaks and bridges, sticky chromosomes, absent or defective cytokinesis, cell fusion, chromatin degeneration and pycnosis, abnormal spindles, giant cells, numerical chromosome variations, dyads, triads, polyads, multinucleate microspores and pollen grains of varying size. Although the frequency of irregularities was high, not all microsporocytes were affected. The present results are compared to literature data about genetic male sterility.