The Role and Functional Structure of 5R Rye Chromosome in Regulation of Meiosis in Wheat - Rye Amphitetraploids
The genetic determination of the control of chromosome pairing in rye (Secale cereale L.) which tolerates with difficulty inbreeding and chromosome abnormalities is much more difficult to analyse than in common wheat. Some approaches in the study of rye genetic factors controlling chromosome pairing focused on analysis of wheat - rye poliploid structures of various chromosome composition. In these study the course of meiosis in diploid wheat/rye AmAmRR amphiploids lacked of wheat Ph1 pairing suppressing gene and carrying the different dose of 5Rs chromosome arm were studied. The identification of kariotypes in respect of 5R-chromosome telocentrics was done with Giemsa C-banding.
In relation to the euploid plants, monotelo-5RL genotypes showed about 23% higher frequency of uniwalents. The number of univalents increased by next 19% in result of elimination of the second 5RS arm in ditelo-5RL genotypes. Similarly, the number of rod bivalents was influenced and their average number per cell in euploid, monotelo-5RL and ditelo-5RL genotypes was 3.83, 5.17 and 6.14 respectively, showing 35% increase in result of one 5Rs arm elimination and next 19% by second 5RS arm elimination. As a result, the general frequency of bounded arms showed to go down from 84.2 to 70.6% and 64.9% paralelly to the diminishing of the number of 5Rs arm present.
Comparisons of three genotypes different in number of 5Rs arm showed x2 values significant both for univalents distribution and number of bounded arms. All these results made it clear that 5Rs arm is carrying highly active locus responsive for the general level of chromosome pairing in AmAmRR amphitetraploid plants. The relation of this locus to the loci known on wheat 5B chromosome in the respect of wheat-rye chromosome synteny is discussed.
Institute of Plant Genetics,