K.R. Boldrini, M.S. Pagliarini, C.B. Valle
Published: December 01, 2009
Genet. Mol. Res. 8 (4) : 1444-1450
DOI: https://doi.org/10.4238/vol8-4gmr679

Cite this Article:
K.R. Boldrini, M.S. Pagliarini, C.B. Valle (2009). Meiotic behavior of a nonaploid accession endorses x = 6 for Brachiaria humidicola (Poaceae). Genet. Mol. Res. 8(4): 1444-1450. https://doi.org/10.4238/vol8-4gmr679

About the Authors
K.R. Boldrini, M.S. Pagliarini, C.B. Valle

Corresponding author
M.S. Pagliarini
E-mail: mspagliarini@uem.br

ABSTRACT

Brachiaria humidicola (Poaceae), originally from Africa, is an economically important pasture plant in tropical South America. An accession of B. humidicola (H038) collected from the wild African savanna (Mbeya, Tanzania) showed irregular microsporogenesis. This meiotic behavior was consistent with an allopolyploid origin. Multivalent chromosome association at diakinesis gave tri- to octavalents, associated with two nucleoli in some cells. Six non-congregated univalents in metaphase I and anaphase I, along with previous lines of evidence for x = 6 in B. humidicola, confirm H038 as a nonaploid accession, 2n = 9x = 54. Asynchrony in the genome during microsporogenesis also corroborated this assumption. Its putative origin could be a cross between two related species with different rhythms in meiosis. The meiotic behavior of this accession reinforces the hypothesis of the existence of a new basic chromosome number (x = 6) for Brachiaria. The use of this accession in the breeding of this important forage grass for the tropics is discussed.

Key words: Brachiaria humidicola, Basic chromosome number, Forage grass, Genome affinity, Meiosis.