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GrainGenes Reference Report: GNM-45-165

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Reference	GNM-45-165
Title	A microsatellite sequence from the rice blast fungus (Magnaporthe grisea) distinguishes between the centromeres of Hordeum vulgare and H. bulbosum in hybrid plants
Journal	Genome
Year	2000
Pages	165-174
Author	Kim NS Armstrong KC Fedak G Ho K Park NI
Abstract	Summary: A TC/AG-repeat microsatellite sequence derived from the rice blast fungus (Magnaporthe grisea) hybridized to all of the centromeres of Hordeum vulgare chromosomes, but hybridized faintly or not at all to the chromosomes of Hordeum bulbosum. Using this H. vulgare centromere-specific probe, the chromosomes of four F1 hybrids between H. vulgare and H. bulbosum were analyzed. The chromosome constitution in the root tips of the hybrids was mosaic, i.e., 7 (7v, H. vulgare) and 14 (7v + 7b H. bulbosum), or 14 (7v + 7b) and 27 (14v + 13b), or 7 (7v), 14 (7v + 7b), and 27 (14v + 13b). The 27-chromosome tetraploid hybrid cells were revealed to have the NOR (nucleolus organizer region) bearing chromosome of H. bulbosum in a hemizygous state, which might indicate some role for this chromosome in the chromosome instability of the hybrid condition. The chromosomal distribution showed that the chromosomes of H. vulgare were concentric and chromosomes of H. bulbosum were peripheral in the mitotic squash. This non-random chromosome distribution and the centromere-specific repeated DNA differences in the two species were discussed in relation to H. bulbosum chromosome elimination. Meiotic chromosome analyses revealed a high frequency of homoeologous chromosome pairing in early prophase. However, this chromosome pairing did not persist until later meiotic stages and many univalents and chromosome fragments resulted. These were revealed to be H. bulbosum by fluorescence in situ hybridization (FISH) analysis with the H. vulgare centromere-specific probe. Because the chromosome segregation of H. vulgare and H. bulbosum chromosomes at anaphase I of meiosis was random, the possibility for obtaining chromosome substitution lines in diploid barley from the diploid hybrid was discussed
Keyword	[ Hide all but 1 of 54 ] barley blast blast fungus cell centromere chromosome chromosome elimination chromosome pairing chromosome segregation chromosome substitution constitution difference diploid dna dna hybridization elimination fish fluorescence fluorescence in situ hybridization fragments frequencies fungus grisea hemizygous high frequency high-frequency hordeum hordeum bulbosum hordeum vulgare hybrid hybridization in situ in situ hybridization instability magnaporthe magnaporthe grisea meiosis mosaicism nucleolus nucleolus organizer nucleotide sequence pairing probe prophase rice rice blast rice blast fungus root segregation sequence species differences state substitution tetraploid

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