B chromosomes in popcorn (Zea mays L.).

Cytological analysis of microsporogenesis in 72 popcorn plants, comprising nine from the original population (CMS-43, S(0)) and 63 from seven cycles of self-fertilization (S(1) to S(7)), one plant of S(0) generation (plant 2) was identified with B chromosomes. The number of B chromosomes varied from two to three in the same anther. The pattern of chromosome pairing and meiotic behavior of Bs were similar to those found in other plant species. The presence of B chromosomes did not affect chiasma frequency and chiasma distribution in A chromosomes. This is the first report of B chromosomes in popcorn.