A peculiar methylation pattern for fine tuning of R gene expression

An unusual epigenetic regulation of NB-LRR resistance genes

Genes conferring resistance to diseases in plants, also named R genes, are essential players of sustainable agriculture. NB-LRR (nucleotide biding site – leucine rich repeat) R genes constitute one of the larger and most diversified gene families in plants. Nevertheless, R genes can represent a cost for plants. Their expression has therefore to be finely tuned. Despite their agronomic importance, this question has been poorly addressed.

Recent results from the IPS2 research team “Genome dynamics and pathogen resistance” (GDYNPATH, directed by V. Geffroy) suggest that NB-LRR genes are controlled at the epigenetic level. More than half of NB-LRR genes in the common bean genome (~200 genes) exhibit methylation in the three methylation context (CG, CHH, CHG). Such a methylation pattern is unusual for protein-encoding genes and is usually characteristic of repeated sequences.

In the near future, the dynamics of NB-LRR methylation after pathogen infection will be investigated. Similar studies will be performed in other crops of agronomic interest.

Richard, M. M. S., A. Gratias, V. Thareau, K. D. Kim, S. Balzergue, J. Joets, S. A. Jackson and V. Geffroy. (2018a). “Genomic and epigenomic immunity in common bean: the unusual features of NB-LRR gene family.” DNA Research, 25 : 161-172. https://doi.org/10.1093/dnares/dsx046