Plant Cell 27, 3175–3189 (2015)

Allelopathy involves the production by plants such as grasses of secondary metabolites that disturb the growth or germination of their neighbours. This interaction often happens through root excretions that diffuse around the rhizosphere, and has ecological importance, as plants using it obtain a fitness advantage by reducing competition. It is crucial for structuring plant communities, including in agricultural ecosystems. Venturelli and colleagues have now discovered one molecular mechanism behind allelopathy that involves chromatin configuration.

Cyclic hydroxamic acids are one of the many substances released by roots. They are quickly degraded in the soil to stable chemical forms, which are potent inhibitors of the highly conserved chromatin-modifying histone deacetylases. In fact, these chemicals are as phytotoxic as a commercial herbicide. In Arabidopsis, they induce hyper-acetylation for hundreds of genes, which then become over-activated, presumably perturbing plant growth and development.

Epigenetic modifications represent a wide-range layer of endogenous gene expression control. This makes dynamic chromatin remodelling an efficient target of choice for co-evolutionary adaptations by foreign organisms: pathogenic or symbiotic microbes, fungi, or in this case, other plants. Understanding this natural warfare can have practical applications, by increasing the repertoire of natural toxins used in agriculture and even in cancer research.