02446naa a2200397 a 450000100080000000500110000800800410001902400570006010000250011724501500014226000090029252012410030165000160154265000170155865000180157565000120159365000220160565000190162765000120164665000160165865000130167465000250168765000270171265000260173965000170176565000160178265000250179865000170182365000120184065000350185265000220188765000110190970000220192070000200194277300860196213264082023-06-19       2007    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1590/S1516-891320070005000112DOI1 aMENDES-BONATO, A. B.  aMeiotic arrest compromises pollen fertility in an interspecific hybrid between Brachiaria ruziziensis x Brachiaria decumbens (PoaceaebPaniceae).  c2007  aMicrosporogenesis was analyzed in an interspecific hybrid between an artificially tetraploidized sexual accession of Brachiaria ruziziensis (2n=4x=36) and a natural apomictic tetraploid accession of B. decumbens. Syncytes involving a large number of cells were recorded in 15.4% of meiocytes. Meiosis progressed normally in syncytes during prophase I; in metaphase I, however, several nuclei were found fusioned, showing chromosome stickiness and several chromosome fragments. Meiosis was arrested in metaphase I and pycnotic nuclei and micronuclei were formed. Abnormal cytokinesis fractionated the syncyte into abnormal meiotic products that were covered by the pollen wall. Meiocytes in leptotene were recorded in all the slides prepared for both meiotic divisions, and abnormal ?pollen grains? with well-developed pollen wall but containing leptotene nuclei were recorded in 9.18% of grains analyzed. These findings suggested that the meiocytes received the signal to enter meiosis but lacked the signal to proceed beyond leptotene. Despite the absence of the meiotic process, such cells were covered by pollen grain wall. Total pollen sterility resulted from these abnormalities combined with still others observed among meiocytes.  aCell fusion  aCytogenetics  aHybridization  aHybrids  aMicrosporogenesis  aPlant breeding  aPoaceae  aPollination  aApomixia  aBrachiaria Decumbens  aBrachiaria Ruziziensis  aCitogenética Vegetal  aEsterilidade  aFertilidade  aGramínea Forrageira  aHibridação  aHibrido  aMelhoramento Genético Vegetal  aPlanta Forrageira  aPólen1 aPAGLIARINI, M. S.1 aVALLE, C. B. do  tBrazilian Archives of Biology and Technologygv. 50, n. 5, p. 831-837, Sep. 2007.