ELIMINATING THE LINKAGE DRAG: A NOVEL METHOD FOR TARGETED ALIEN GENE TRANSFER Abstract uri icon

abstract

  • Regulation of meiotic recombination between wild and cultivated species limits the transfer of wealth of desirable genes/alleles from wild species. The currently available methods of alien gene transfer are time-consuming, cumbersome and result in the transfer of complete chromosome/arm creating undesirable linkage drag. We are reporting that manipulation of homoeologous recombination via transient silencing of C-Ph1 gene results in 26% recombinant gametes between wheat and rye chromosome compared to no recombination in controls. With an average of "3 crossovers between 1BS and 1RS, the size of transferred alien fragments ranged from 40kb to 214Mb. A 100kb long recombination hotspot highlights the uneven distribution of homoeologous recombination. The number of alien segments transferred in the distal 1/3rd region of the chromosome arm ranged from 1-5 with an average of "2.4 segments per recombinant plant. Multiple introgression segments present on the arm were segregated out for targeted gene transfers via recombination in the following generation involving interspersing wheat segments. Apart from its known effect on homoeologous recombination, increase in Ph1 dosage have shown to reduce chromosome pairing and chiasmata formation. The average number of homologous crossovers for chromosome 5B for control and treatment population was "1.6 and "2.2 respectively (p-value<0.0001). Further, both the number of single crossovers ("0.6) and double crossovers ("0.87) were significantly higher in treatment compared to the control population ("0.4 & 0.6). Thus, suggesting that C-Ph1 regulates both homologous and homoeologous recombination in polyploid wheat.

publication date

  • July 2019