Multiple spindles and cellularization during microsporogenesis in an artificially induced tetraploid accession of Brachiaria ruziziensis (Gramineae)

The genus Brachiaria is characterized by a majority of polyploid accessions--mainly tetraploid--and apomictic reproduction. Sexuality is found among diploids. To overcome incompatibility barriers, accessions with the same ploidy level are necessarily used in hybridization. Thus, sexual diploid acces...

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Bibliographic Details
Published in:Plant cell reports 2005-01, Vol.23 (8), p.522-527
Main Authors: Risso-Pascotto, C, Pagliarini, M.S, Valle, C.B. do
Format: Article
Language:English
Subjects:
Biological and medical sciences
Biotechnology
Brachiaria - cytology
Brachiaria - drug effects
Brachiaria - genetics
Brachiaria - physiology
Brachiaria ruziziensis
Chromosomes
Colchicine - pharmacology
Eukaryotic cell cultures
Fundamental and applied biological sciences. Psychology
Meiosis - genetics
Methods. Procedures. Technologies
microsporogenesis
Miscellaneous
Plant cells and fungal cells
Pollen
Polyploidy
Spindle Apparatus - physiology
tetraploidy
Urochloa ruziziensis
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Summary:The genus Brachiaria is characterized by a majority of polyploid accessions--mainly tetraploid--and apomictic reproduction. Sexuality is found among diploids. To overcome incompatibility barriers, accessions with the same ploidy level are necessarily used in hybridization. Thus, sexual diploid accessions were tetraploidized to be used as female genitors. This paper reports microsporogenesis in an artificially induced tetraploid accession of Brachiaria ruziziensis. Chromosome pairing at diakinesis ranged from univalents to tetravalents, with predominance of bivalents. Irregular chromosome segregation was frequent in both meiotic divisions. During the first division, multiple spindles showing different arrangements were recorded. The spindle position determined the plane of first cytokinesis and the number of chromosomes determined the size of the cell. Meiotic products were characterized by polyads with spores of different sizes. Pollen sterility was estimated at 61.38%. The limitations of using this accession in the breeding program are discussed.
ISSN:0721-7714
1432-203X
DOI:10.1007/s00299-004-0867-y