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GrainGenes Reference Report: GNM-43-232

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Reference	GNM-43-232
Title	Relationship between pachytene synapsis, metaphase I associations, and transmission of 2B and 4B chromosomes in rye
Journal	Genome
Year	2000
Volume	43
Pages	232-239
Author	Jimenez G Manzanero S Puertas M Puertas MJ
Abstract	Summary: 2B rye plants selected for high (H) or low (L) B transmission rate were studied at pachytene and metaphase I of meiosis to determine the relationship between synapsis, bivalents at metaphase I, and B transmission rate. The results show that the 2 B chromosomes (Bs) form bivalents at pachytene in both the H and L lines, whereas the frequency of bivalents at metaphase I is much higher in the H than in the L line. This demonstrates that B transmission is mainly related to the proper association of Bs at metaphase I, as well as that synapsis of the 2 Bs in the L line is normal, but the bivalent is not consolidated by a chiasma in most cases. Crosses were made between 2B plants of the H and L lines in all combinations (H x H, H x L, L x H, and L x L) to obtain 4B plants. Similarly, bivalent formation at pachytene and metaphase I was studied. The results show that 4B plants of the H x H and L x L classes differ significantly at pachytene and metaphase I since the former forms more bivalents. The heterozygous 4 Bs of the H x L and L x H classes show intermediate values. The relation H x H > H x L > L x H > L x L was consistently found for the variables transmission rate, bivalents at pachytene, bivalents at metaphase I, and B mean chiasma frequency. A maternal effect was also found. Our data suggest that there are two separate mechanisms acting upon synapsis and chiasma formation in H and L B chromosomes: (i) there is variable efficiency of the control of synapsis at early stages of meiosis: and (ii) there is variable efficiency of the control of the number of chiasmata
External Databases	Pubmed: 10791810
Keyword	b chromosomes [ Show all 28 ]

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