Microsporogenesis in Brachiaria bovonei (Chiov.) Robyns and B. subulifolia (Mez) Clayton (Poaceae)

Scientia Agricola

Claudicéia Risso-pascotto¹  Maria Suely Pagliarini¹  Cacilda Borges Do Valle² 

[1] ,Embrapa Gado de CorteCampo Grande MS ,Brasil

关键词: Brachiaria;    meiosis;    chromosome number;    polyploidy;    breeding program;    Brachiaria;    meiose;    número de cromossomos;    poliploidia;    melhoramento;   

DOI  :  10.1590/S0103-90162009000500015

来源: SciELO

【 摘 要 】

Some African species of Brachiaria have been introduced into the Americas and became the most important forage for pastures in the tropics. New cultivars can be obtained either from direct selections from the natural existing variability in the germplasm collections or from interspecific hybridizations. Polyploidy is predominant in the genus Brachiaria and correlated with apomixis which complicates hybridization. The objective of cytological studies underway on the Brachiaria germplasm collection at Embrapa Beef Cattle is to determine the chromosome number and meiotic behavior of accessions. For the breeding of Brachiaria species, compatible sexual and apomictic accessions need to be identified. Microsporogenesis was evaluated in two accessions of Brachiaria bovonei (BO01 and BO05) and one accession of B. subulifolia (SU01). BO01 is pentaploid (2n = 5x = 45), BO05 is tetraploid (2n = 4x = 36), and SU01 is hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities typical of polyploids, characterized by precocious chromosome migration to the poles in metaphases, laggard chromosomes in anaphases, and micronuclei in telophases and tetrads, were recorded in high frequency in all the accessions generating unbalanced gametes. Both accessions of B. bovonei presented chromosome stickiness. The results are discussed in the view of the Brachiaria breeding program objectives.

【 授权许可】

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