Genetic Mechanisms of Hybrid Incompatibility in Plants

Hybrid incompatibility in plants arises when divergent genomes fail to cooperate in F₁ or later generations, leading to inviability, developmental arrest or sterility. These phenomena are most often postzygotic, manifesting as hybrid lethality, hybrid necrosis or hybrid weakness. Underlying causes conform to the Dobzhansky–Muller model, in which independent mutations in separate lineages interact negatively when combined in a hybrid. Immune‐related genes, particularly nucleotide‐binding leucine‐rich repeat receptors (NLRs), frequently underlie autoimmune‐like responses that trigger cell death or growth arrest. In other cases, imbalance of parental genome contributions in the endosperm (effective ploidy) impedes seed development. Environmental factors such as temperature and light can modulate the severity of incompatibility. Genetic mapping and molecular analyses across diverse taxa—from Arabidopsis and rice to wheat and tobacco—have identified specific loci and allelic combinations responsible for these barriers. Understanding these mechanisms is vital for overcoming reproductive obstacles in wide crosses, enabling introgression of beneficial traits from wild relatives and enhancing crop resilience.

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Genetic Mechanisms of Hybrid Incompatibility in Plants publication trend

The graph below shows the total number of articles in genetic mechanisms of hybrid incompatibility in plants across all publications each year (not limited to Nature Index journals).

Technical terms

Postzygotic reproductive isolation: A barrier to gene flow occurring after fertilisation, leading to hybrid inviability or sterility.

Dobzhansky–Muller interaction: Epistatic incompatibility arising when alleles that evolved separately in distinct lineages interact deleteriously in hybrids.

Hybrid lethality: A form of incompatibility causing death of the embryo or young seedling.

Hybrid necrosis: Autoimmune‐like cell death in hybrid plants, often involving the upregulation of defence‐related genes.

Epistasis: Non‐additive interaction between alleles at different loci affecting phenotype.

Nucleotide‐binding leucine‐rich repeat receptor (NLR): A class of intracellular immune receptors that detect pathogen effectors and can trigger defence responses, including hybrid necrosis.

Amphiploid: A polyploid organism containing complete chromosome sets from two distinct species, often used in wide hybridization studies.

References

1. Genetic Cause of Hybrid Lethality Observed in Reciprocal Interspecific Crosses between Nicotiana simulans and N. tabacum. International Journal of Molecular Sciences (2024).
2. Phenotypic characterization and gene mapping of hybrid necrosis in Triticum durum–Haynaldia villosa amphiploids. Theoretical and Applied Genetics (2024).
3. Understanding and overcoming hybrid lethality in seed and seedling stages as barriers to hybridization and gene flow. Frontiers in Plant Science (2023).