Hybrids face a battle for dominance of the genome

When two different genomes come together in a hybrid or polyploid, it can trigger conflict in the new genome. A review in New Phytologist investigates how one subgenome can become dominant.
An attempt to illustrate the genetic potential in polyploidy
Can studying subgenomes make the potential of crops less murky? Image: Canva.

Typically students are taught how plants take on board DNA from their parent ovule and pollen to create a new diploid (two chromosome) plant. They generate new haploid (one chromosome) ovules and pollen and these travel to form new plants. So the cycle continues, alternating between generations of one or two chromosomed organisms.

Reality can be a lot messier. For example, what happens if the wrong pollen fertilizes an ovule?

Usually nothing, but sometimes the genetic code is close enough to produce a hybrid, a cross between the two parent plants. On other occasions instead of getting one chromosome from each parent, the plant gets more becoming an allopolyploid, with genes to spare.

In ordinary practice, a plant can inherit a mix of dominant and recessive versions of genes, known as alleles. In an article in New Phytologist, Kevin Bird and colleagues look into how a whole genome, or rather sub-genome, can become dominant when a plant hybridizes.

Getting to grips with the genetic mechanics of hybridization could be of great value. The authors write: “Knowing if a subgenome will become dominant or recessive may allow breeders to better predict which crosses will yield desired traits. Alleles associated with favorable agronomic traits may be masked if they are introgressed into a more dominant genome background, or undesirable alleles may be unmasked from a newly dominant subgenome.”

Further reading

Bird, K. A., VanBuren, R., Puzey, J. R., & Edger, P. P. (2018). The causes and consequences of subgenome dominance in hybrids and recent polyploids. New Phytologist. https://doi.org/10.1111/nph.15256