Plants harm themselves with their own DNA

What is it about?

Sometimes plants can be their own worst enemies. Negative plant-soil feedback refers to the process by which plants create a hostile environment for themselves in the very soil they inhabit. The mechanisms underlying this phenomenon are very much up for debate. One idea involves the decomposition of plant litter releasing chemicals into the soil that are toxic to the very plants that they have originated from – something referred to as autotoxicity. DAMAGING DNA To comprehensively test the idea of autotoxicity, authors of this paper undertook experiments involving 20 different plant species. The tests involved examining the effects of their own litter against litter produced by other plants, as well as the hypothesis that it is in fact extracellular DNA within the litter that is responsible for autotoxic effects. INCREASING SPECIFICITY Intriguingly, the team found that while undecomposed litter caused general inhibition of root growth for all plants, as the litter aged and continued to decompose its inhibitory effects became more specific to the plant it originated from – it became autotoxic. This strongly suggests that this mechanism lies at the heart of the mysterious process of negative plant-soil feedback. Moreover, the follow-up of the research by the same team has shown how this toxicity effect is not limited to plants and can be found in other biological systems. This unexpected finding raises a number of questions, notably concerning the way in which accumulated extracellular DNA may act as a significant selection pressure driving evolutionary processes. The researchers recommend further investigation into the molecular mechanisms of extracellular self-DNA toxicity.

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