| The wheat x rye hybrids using mutant ph exhibited relatively high
homoeologous pairing with mean chromosome associations of 5.7 bivalents,
13.2 univalents and 0.94 multivalents (0.58 trivalents, 0.37 quadrivalents
and 0.004 pentavalents) per PMC in ph x Kc-517/8, and 4. 99 bivalents,
16.3 univalents and 0.54 multivalents (0.41 trivalents. 0.11 quadrivalents
and 0.01 hexavalents) in ph x Pamirskaya (Table
1). The amount of homoeologous pairing in hybrid derived from crossing
between mutant ph and self-fertile line Kc-517/8 was significantly
higher than in hybrid ph x Pamirskaya. Percent of PMCs with multivalents
in ph x Kc-517/8 was equal 58.5 (from 1 to 4 multivalents per cell).
In hybrid ph x Pamirskaya 37.9 per cent of PMCs With multivalents
was observed (Table 2). It seems quite probable that the high amount of bivalent and multivalent associations at MI of meiosis in hybrid ph x Kc-517/8, compared to the combination ph x Pamirskaya, are conditioned by cytogenetical peculiarities of self-fertile line of rye Kc-517/8. Cytological analysis of meiosis in this line of rye has revealed considerable disturbances of meiotic processes, which apparently were the results of mutations which occurred in the course of premeiotic division of mitosis and were determined genotypically (SHlNAIDER & FADEJEVA 1983 ; SHNAIDER et al. 1983). This line of rye is characterized by unstability of meiosis and may produce gametes with unbalanced chromosome numbers. In the present experiment the combining of genotypes of mutant ph and self-fertile line of rye resulted in increasing of induced homoeologous pairing with the high average numbers of multivalent configurations at MI of meiosis. Undoubtedly the rye genotype plays an important role in the forming of intergeneric hybrids and has an effect on the behaviour of meiosis. The mutant ph was found effective in inducing homoeologous pairing of chromosomes in wheat x rye hybrids. References OKAMOTO, M. 1957. Wheat Inf. Serv. 5 : 6. RILEY, R. 1960. Heredity 15 : 407-429. RILEY, R. & CHAPMAN, V. 1958. Nature 182 : 713-715. SEARS, E.R. & OKAMOTO, M. 1958. Proc. 10th Intern. Congr. Genet. Montreal, 2 : 258-259. SEARS, E.R. 1973. Wheat Genet. Symp., Columbia, USA : 28-38. SEARS, E.R. 1977. Canad. J. Genet. Cytol. 19 : 585-593. SEARS, E R 1980. In "Wheat Science-today and tomorrow" Cambridge Univ Press : 75-89. SHNAIDER, T. & FADEJEVA, T. 1983. Proc. Acad. Sci. of the Estonian S.S.R, Biology, 32 : 33-39. SHNAIDER, T. & PRIILINN, O. & FADEJEVA, T. 1983. Proc. 15th Intern. Congr. Genet., New Delhi, 2 : 684. WALL, A.M., RILEY, R. & GALE, M.D. 1971. Genet. Res. 18 : 329-339. |
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