ABSTRACT
Endogamy places genes for several characteristics in homozygosis, which include those related to meiosis causing abnormalities that may impair gamete viability. An original population (S0) of popcorn (CMS-43) produced by Embrapa Maize and Sorghum was self-pollinated for seven years, generating inbred lines (S1 to S7). Conventional studies of microsporogenesis revealed that meiotic abnormalities did not increase with endogamy. Univalent chromosomes, irregular chromosome segregation, abnormal cell shape, partial asynapsis, cell fusion, absence of cytokinesis, abnormal spindle orientation, and chromosome stickiness were recorded in low frequency in meiocytes. Since the frequency of abnormalities was low, mainly in S7, inbred lines from CMS-43 have a high potential for hybridization.
Subject(s)
Inbreeding , Meiosis/genetics , Zea mays/genetics , Cytokinesis/genetics , Chromosomes, Plant/genetics , Gametogenesis , Zea mays/cytology , Zea mays/growth & development , Zea mays/physiologyABSTRACT
Cytological analysis of microsporogenesis in 72 popcorn plants, comprising nine from the original population (CMS-43, S0) and 63 from seven cycles of self-fertilization (S1 to S7), one plant of S0 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