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GrainGenes Reference Report: PBR-122-136

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Reference	PBR-122-136
Title	Chromosome number and microsporogenesis in a pentaploid accession of Brachiaria brizantha (Gramineae)
Journal	Plant Breeding
Year	2003
Volume	122
Pages	136-140
Author	Risso-Pascotto C Pagliarini MS do Valle CB Mendes-Bonato AB
Abstract	Summary: Chromosome number, microsporogenesis and mode of reproduction are described for an accession of Brachiaria brizantha, a grass of African origin. Cytological analysis revealed that the accession BRA005886 is pentaploid (2n = 5x = 45), with a base number of x = 9. Multivalent chromosome associations, from tri- to pentavalents, were recorded in diakinesis, and the further meiotic behaviour was highly irregular as well. Most abnormalities were related to irregular chromosome segregation commonly found in polyploids. Micronuclei were observed following telophases I and II. Some micronuclei near the cell wall were released as microcytes, whereas others remained in the tetrad. Other meiotic abnormalities, such as cell fusion and the absence of cytokinesis causing the formation of dyads and triads were also recorded. Binucleate microspores and 2n microspores resulting from nucleus restitution were observed among the normal ones. Limitations of this accession for use in hybridization programmes are discussed
Keyword	[ Hide all but 1 of 25 ] 2n gametes absence absence of cytokinesis apomixis associations base brachiaria brizantha cell cell fusion cell wall chromosome chromosome number chromosome-number cytokinesis decumbens fusion gramineae hybridization limitations microsporogenesis nucleus origin polyploid reproduction segregation

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