Abstract

Gametocidal (Gc) chromosomes or elements in species such as Eig are preferentially transmitted to the next generation through both the male and female gametes when introduced into wheat ( L.). Furthermore, any genes, such as genes that control agronomically important traits, showing complete linkage with Gc elements, are also transmitted preferentially to the next generation without the need for selection. The mechanism for the preferential transmission of the Gc elements appears to occur by the induction of extensive chromosome damage in any gametes that lack the Gc chromosome in question. Previous studies on the mechanism of the Gc action in indicates that at least two linked elements are involved. The first, the element, induces chromosome breakage in gametes, which have lost the Gc elements while the second, the element, prevents the chromosome breakage action of the breaker element in gametes which carry the Gc elements. In this study, we have used comparative genomic studies to map 54 single nucleotide polymorphism (SNP) markers in an 4S introgression segment in wheat and have also identified 18 candidate genes in for the breaker element through targeted sequencing of this 4S introgression segment. This valuable genomic resource will aide in further mapping the Gc locus that could be exploited in wheat breeding to produce new, superior varieties of wheat.

Highlights

  • Certain Aegilops species have an evolutionary unique mechanism that ensures the transmission of specific regions of their genomes to the generation when introduced to wheat

  • The presence of the Ae. sharonensis introgression in IL T4B-4Ssh and its EMS-mutant counterpart was detected by a genomic DNA probe of Ae. sharonensis followed by multi-colour Genomic in situ hybridisation (GISH) to indicate the wheat chromosome containing the translocation

  • GISH with a genomic DNA probe of Ae. sharonensis was performed on Ae. sharonensis, the CS(4B)4Ssh substitution line and ILs T4B-4Ssh and T4B-4Ssh#1 followed by multi-colour GISH on these lines

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Summary

Introduction

Certain Aegilops species have an evolutionary unique mechanism that ensures the transmission of specific regions of their genomes to the generation when introduced to wheat This phenomenon was first recognized when specific chromosomes, “Gametocidal” chromosomes (‘Gc’, (Endo, 1978)) or “Cuckoo” chromosomes (Finch et al, 1984), were observed to be preferentially transmitted through both the male and female gametes in a wheat background. Only gametes carrying the Gc element are transmitted to the generation Those traits linked with gametocidal elements, are found in all offspring without the requirement for selection, a genetic phenomenon that may have significant practical application in plant breeding (Endo and Gill, 1996; King et al, 1991). The role of the second element, the ‘inhibitor’ element, is to prevent the chromosomal breakage action of the ‘breaker’ element in gametes that have retained the Gc elements (Endo, 1990; Friebe et al, 2003; Tsujimoto, 2005)

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