Desynapsis and precocious cytokinesis in Brachiaria humidicola (Poaceae) compromise meiotic division.
The forage grass species Brachiaria humidicola is native to African savannas. Owing to its good adaptation to poorly drained and infertile acid soils, it has achieved wide utilization for pastures in Brazilian farms. Among the 55 accessions of B. humidicola analysed from the Embrapa Beef Cattle collection, one (H022), presented desynapsis and an abnormal pattern of cytokinesis in the first meiotic division. Among 28 inflorescences analysed in this accession, 12 were affected by the anomaly. In affected meiocytes, the first cytokinesis occurred in metaphase I and was generally perpendicular to a wide-metaphase plate, dividing the genome into two parts with an equal or unequal number of chromosomes. The normal cytokinesis after telophase I did not occur, and the meiocytes entered metaphase II, progressing to the end of meiosis with the occurrence of the second cytokinesis. As the first cytokinesis occurred precociously, whereas the second was normal, tetrads were formed but with unbalanced chromosome numbers in microspores. Abnormal cytokinesis occurred only in those meiocytes that underwent desynapsis after diakinesis. The implications of this abnormality in the Brachiaria breeding programme are discussed.
Calisto
Vergílio
V
Department of Cell Biology and Genetics, State University of Maringá, 87020-900 Maringá, Paraná, Brazil.
Fuzinatto
Veridiana Aparecida
VA
Message
Hugo José
HJ
Mendes-Bonato
Andréa Beatriz
AB
Boldrini
Kellen Regina
KR
Pagliarini
Maria Suely
MS
do Valle
Cacilda Borges
CB
D000821:Animal Feed; D035201:Brachiaria / Q000166:cytology* / Q000235:genetics*; D001938:Brazil; D001947:Breeding; D048749:Cytokinesis / Q000235:genetics; D008540:Meiosis / Q000235:genetics