THE ROLE OF GENES FOR THE EQUATIONAL DIVISION OF UNIVALENTS IN INTERGENOMIC CHROMOSOME SUBSTITUTION

The progeny of wheat-rye di-monosomics 5R-5A and 5A-5D of Triticum aes tivum L. (cv. Saratovskaya 29) and Secale cereale L. (cv. Onokhoiskaya ) differing in the dosage of the gene P(Edu), the promoter of the equa tional division of univalents, located on rye chromosome 5R was studie d. In the progeny of each di-monosomic, the variation In intergenomic chromosome substitutions was observed. In di-monosomics 5R-5A with one dosage of the gene P(Edu), the frequency of plants with 5R(5A) substi tution was 9.64%, while the frequency of plants with SA(SR) substituti on was 28.91%; in di-monosomics 5A-5D with two dosages of this gene, 4 2.73% of plants carried the substitution 5D(5A), and 0.91% of plants h ad the substitution 5A(5D). The differences in. the pattern of interge nomic chromosome substitutions in the progeny of self-pollinated wheat -rye di-monosomics 5R-5A and 5A-5D was shown to be due to the variant transmission rate of their univalent chromosomes. It was demonstrated that two. nonhomologous univalent chromosomes of these di-monosomics w ere transmitted with different frequencies both through maternal and p aternal gametes. In di-monosomics 5R-5A, the univalent chromosome 5R w as transmitted via 20.2% of maternal gametes and, in 30.1% of cases, i t was transmitted via paternal gametes. The second univalent chromosom e 5A of this di-monosomic was much more often transmitted through mega spores and pollen with frequencies of 46.7 and 58.9%, respectively. In di-monosomics 5A-5D, the variation is much more pronounced. Chromosom e 5A was transmitted via 11% of-maternal gametes and 17% of paternal g ametes, while chromosome 5D was transmitted by maternal gametes in 62% of cases and by paternal gametes in 69% of cases. No variation in the transmission of aneuploid gametes via the pollen between di-monosomic s 5R-5A and 5A-5D was found. The gametes with n = 22 were not discover ed, while those with n = 20 were transmitted only in 11-13% of cases. Based on the results obtained, it was concluded that the genes control ling the equational division of univalents at AI of meiosis significan tly affect the pattern of intergenomic substitutions in aneuploid prog eny. Different dosages of these genes are responsible for the level of equational division of nonhomologous univalent chromosomes and the fr equency of their transmission via gametes.