02324naa a2200325 a 450000100080000000500110000800800410001910000250006024501330008526000090021852013650022765000150159265000190160765000220162665000190164865000250166765000150169265000250170765000350173265000130176765000160178065300220179670000210181870000240183970000150186370000160187870000220189470000200191677300620193613270502023-08-22       2009    bl uuuu     u00u1 u    #d1 aMENDES-BONATO, A. B.  aAbnormal meiosis in tetraploid genotypes of Brachiaria brizantha (Poaceae) induced by colchicinebits implications for breeding.  c2009  aMeiotic behavior was analyzed in 6 progenies from 3 artificially induced tetraploid (2n = 4x = 36) sexual genotypes (C31, C41, and C48) of the normally apomictic Brachiaria brizantha (Hochst. ex A. Rich.) Stapf., syn. Urochloa brizantha (Hochst. ex A. Rich.) R. Webster. These are key plants to allow intraspecific hybridization of this important forage species, widely used for pastures in the tropics. The percentage of abnormal cells among the plants ranged from 39.8% to 63.2%. In the single plant derived from C48, only the common meiotic abnormalities typical of polyploids were observed, while in plants derived from C31 and C41, a distinct behavior was found. In the majority of cells of those plants, the chromosomes remained scattered in the cytoplasm in the first division, without forming a metaphase plate. This abnormality blocked chromosome movements at anaphase I. Several micronuclei of various sizes were formed and, after the occurrence of an irregular first cytokinesis, the meiocytes progressed normally to the second division, generating polyads with unbalanced microspores. Pollen viability was not correlated with meiotic abnormalities. The importance of these findings to the Brachiaria breeding program is discussed. The sexual progeny of C48 seems most suitable as female parents to be used in intra- and interspecific hybridization.  aColchicine  aForage grasses  aMicrosporogenesis  aPlant breeding  aBrachiaria Brizantha  aColchicina  aGramínea Forrageira  aMelhoramento Genético Vegetal  aPastagem  aPoliploidia  aMicrosporogênese1 aFELISMINO, M. F.1 aKANESHIMA, A. M. S.1 aPESSIM, C.1 aCALISTO, V.1 aPAGLIARINI, M. S.1 aVALLE, C. B. do  tJournal of Applied Geneticsgv. 50, n. 2, p. 83-87, 2009.