Gene mutations in rye causing embryo lethality in hybrids with wheat: allelism and chromosomal localisation

Abstract

In crosses between hexaploid wheat and inbred lines of rye, a small number of rye genotypes produce seeds carrying undifferentiated, non-viable embryos. Hybrids between such lines and those not showing this phenotype were used as pollen donors in crosses with bread wheat in order to determine the genetic basis of disturbed embryo development. A single gene, designated Eml-R1b, is causing this character. Molecular markers associated with F 2 genotypes derived from a contrasting rye inbred progeny were used for a linkage study. Recombinant inbred lines of an F 5 population served as testers. Eml-R1b maps to chromosome arm 6RL, along with two co-segregating microsatellite loci, Xgwm1103 and Xgwm732. Complementary interactions of deleterious genes in wheat and rye are discussed.

Embryo lethality in wheat × rye hybrids—mode of inheritance and the identification of a complementary gene in wheat

“…Certain combinations of bread wheat and rye generate hybrid caryopses carrying undifferentiated nonviable embryos, and the major gene Eml-R1 has been shown to be responsible for inducing embryo lethality (Tikhenko et al 2005(Tikhenko et al , 2010. Its mode of inheritance had not previously been determined, but here we have been able to show that at least two allelic forms are present in rye germplasm, with the b allele (as described by Tikhenko et al 2010) being dominant over the a allele.…”

“…The correctness of the WRAs was proved by testing them with the two SSR markers GWM732-6R and GWM1103-6R (Khlestkina et al 2004) having rye (Imperial, L2, L6) specific alleles in contrast to CS. Both co-segregating markers were detected to be linked to Eml-R1 by Tikhenko et al (2010).…”

“…Considering the syntenic blocks existing for wheat and rye (Devos et al 1993) and the fact that Eml-R1 was located on chromosome 6RL (Tikhenko et al 2010) it may be suggested that Eml-A1 bis located on chromosome 6AL. To confirm the correct nullisomic conditions of the Nulli-6A lines and the hybrid nature of the viable offsprings produced from crosses between the Nulli-6A lines with L2 again SSR analysis was performed.…”

“…When hybrids between these lines and others which produced fully viable hybrid progeny were used to pollinate CS wheat, it was possible to show that the single gene Eml-R1 is responsible for the embryo lethality character. Eml-R1 was located by genetic mapping to chromosome 6RL (Tikhenko et al 2010). As the dominance relationships of the alternative Eml-R1 alleles were not determined, they had to be designated Eml-R1a (wild type, normal embryos) and Eml-R1b (mutant, lethal embryos) (Tikhenko et al 2010) following standard gene nomenclature rules (McIntosh et al 2008).…”

“…Eml-R1 was located by genetic mapping to chromosome 6RL (Tikhenko et al 2010). As the dominance relationships of the alternative Eml-R1 alleles were not determined, they had to be designated Eml-R1a (wild type, normal embryos) and Eml-R1b (mutant, lethal embryos) (Tikhenko et al 2010) following standard gene nomenclature rules (McIntosh et al 2008).…”