02315naa a2200301 a 450000100080000000500110000800800410001910000250006024500780008526000090016350000190017252014750019165000220166665000120168865000220170065000180172265000250174065000110176565000350177665000130181165000160182465300220184065300160186270000230187870000220190170000200192377300700194313270232023-07-20       2006    bl uuuu     u00u1 u    #d1 aMENDES-BONATO, A. B.  aChromosome number and meiotic behaviour in Brachiaria jubata (Gramineae).  c2006  aResearch note.  aThe production of new genetic variability through hybridization has been undertaken in Brachiaria, an important forage grass genus of African origin widely used in pastures in the Brazilian tropics. Although the genus comprises about 100 species, only a few of them present favourable agronomic attributes and are explored. In the genus Brachiaria, the majority of species and accessions are polyploid and apomictic, which makes breeding through hybridization more complex. Sexuality has been found in diploids and eventually among tetraploids with normal meiosis. Brachiaria jubata presents good forage value and adaptation to riverbanks and lake margins, and is therefore relevant to pasture systems in the tropics. Furthermore, the most interesting form of resistance to spittlebugs?antibiosis?was identified in one accession of B. jubata. Thus its interest in the Brazilian breeding programme lies in the possibility of using hybridization to transfer high resistance to this insect to susceptible accessions. This paper reports chromosome numbers and meiotic behaviour in 21 accessions of this species as a tool in selecting promising ones for crossing. Only one accession was found to be diploid; the others were tetraploid. Microsporogenesis was normal in the diploid accession, while among the tetraploid ones, irregular chromosome segregation leading to unbalanced gamete formation was common but variable. Pollen fertility among tetraploid accessions was high.  aChromosome number  aMeiosis  aMicrosporogenesis  aCitogenética  aGramínea Forrageira  aMeiose  aMelhoramento Genético Vegetal  aPastagem  aPoliploidia  aBrachiaria jubata  aBraquiária1 aRISSO-PASCOTTO, C.1 aPAGLIARINI, M. S.1 aVALLE, C. B. do  tJournal of Genetics, Bangaloregv. 85, n. 1, p. 83-87, Apr. 2006.