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A gibberellic acid-insensitive dwarfing gene in rye (ct1) was mapped in an F2 population on chromosome 7R close to the centromere. Two RFLP markers were found, which flank the gene at distances of 1 and 3 cM, respectively. A total of 11 markers were mapped on 7R of which six cluster around the centromere and show segregation distortion in the case of the codominant markers. The ct1 gene is closely linked to copies of both α-amy1ase and EmBP, as is the ct2 gene on chromosome SR. Because of the different chromosomal locations of the GA2-insensitive dwarfing genes in rye and wheat it is concluded that these genes are not homoeologous. This is supported by further differences in their phenotypic and genotypic expressions. [ABSTRACT FROM AUTHOR]

Under field conditions in Germany over three growing seasons the pleiotropic effects on yield and its components of four sets of near isogenic lines carrying the GA insensitive dwarfing alleles Rhtl, Rht2, Rht3, Rht1+2, Rht2+3 or rht (tall) in four different genetical backgrounds were examined together with 24 single chromosome recombinant lines segregating for the GA sensitive dwarfing gene Rht8 and the gene for day-length insensitivity Ppd1 in a 'CappelleDesprez' background. For the GA insensitive semidwarfs it was shown that in all three years a higher number of grains per ear was accompanied by a lower grain weight. Depending on the climatic conditions in a particular year, the increase in grain number was sufficient to compensate for the reduction in grain size and resulted in higher yields. For the Ppdl allele yield advantages were found for wheats grown under environmental conditions of middle Europe. [ABSTRACT FROM AUTHOR]

The article presents information on differences in recombination frequency during male and female gametogenesis in rye, Secale cereale L. With the advent of genetic mapping, differences in recombination frequencies during male and female meiosis have become apparent. A number of considerations lead to the conclusion that there is little reason why the recombination frequencies should be same in both sexes. An analysis of the timing of micro- and macrosporogenesis in rye has shown that, within a floret, both the onset of meiosis and gametophyte maturity are synchronous. The critical phases of meiosis where recombination occurs are not synchronous, with the succession being noticeably slower in the female.