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Natural expression variation for the Arabidopsis MED20a mediator complex subunit influences quantitative resistance to Sclerotinia sclerotiorum

Summary

Scientists studied how different varieties of a common plant (Arabidopsis) naturally resist a destructive fungal disease caused by Sclerotinia sclerotiorum. By examining genetic differences among plant varieties and testing a fungus from different sources, they found that a gene called MED20a plays an important role in disease resistance. Plants with specific genetic variations in the MED20a gene’s control region were more resistant to infection.

Background

Sclerotinia sclerotiorum is a destructive necrotrophic fungal pathogen affecting many crop species. Resistance to this pathogen is partial and quantitative, controlled by multiple genes. Previous studies have identified specific defense pathways and mediator complex subunits involved in resistance mechanisms.

Objective

To perform genome-wide association studies of Arabidopsis thaliana response to two S. sclerotiorum isolates differing in aggressiveness and identify causal genes at mapped loci contributing to quantitative resistance. The study aimed to understand natural genetic variation underlying resistance differences among plant ecotypes.

Results

GWAS mapped 30 loci associated with resistance to S. sclerotiorum with surprisingly weak correlations between responses to the two isolates and no overlapping loci. Med20a mutants showed significantly increased susceptibility to both isolates. A C/A polymorphism 1,214 bp upstream of MED20a correlated with resistance, with differential MED20a expression patterns observed between resistant and susceptible ecotypes.

Conclusion

Natural variation in MED20a expression influences quantitative resistance to S. sclerotiorum, with a promoter variant associated with enhanced resistance. The study demonstrates that S. sclerotiorum isolate diversity significantly impacts resistance mapping and that the transcriptional mediator complex plays an important role in defense against this pathogen.
  • Published in:Frontiers in Plant Science,
  • Study Type:Genome-wide Association Study,
  • Source: PMC12667439, PMID: 41334202
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