title: Inhibitory and toxic effects of extracellular self-DNA in litter: a mechanism for negative plant-soil feedbacks?
abstract: Plant-soil negative feedback (NF) is recognized as an important factor affecting plant communities. The objectives of this work were to assess the effects of litter phytotoxicity and autotoxicity on root proliferation, and to test the hypothesis that DNA is a driver of litter autotoxicity and plant-soil NF. The inhibitory effect of decomposed litter was studied in different bioassays. Litter biochemical changes were evaluated with nuclear magnetic resonance (NMR) spectroscopy. DNA accumulation in litter and soil was measured and DNA toxicity was assessed in laboratory experiments. Undecomposed litter caused nonspecific inhibition of root growth, while autotoxicity was produced by aged litter. The addition of activated carbon (AC) removed phytotoxicity, but was ineffective against autotoxicity. Phytotoxicity was related to known labile allelopathic compounds. Restricted (13) C NMR signals related to nucleic acids were the only ones negatively correlated with root growth on conspecific substrates. DNA accumulation was observed in both litter decomposition and soil history experiments. Extracted total DNA showed evident species-specific toxicity. Results indicate a general occurrence of litter autotoxicity related to the exposure to fragmented self-DNA. The evidence also suggests the involvement of accumulated extracellular DNA in plant-soil NF. Further studies are needed to further investigate this unexpected function of extracellular DNA at the ecosystem level and related cellular and molecular mechanisms.
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mazzoleni
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Bonanomi
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Incerti
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Chiusano
authors.affiliation: CNR-IGV, Istituto di Genetica Vegetale, via Università 133, 80055, Portici (NA), Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Termolino
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Mingo
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Senatore
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Giannino
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Cartenì
authors.affiliation: Department of Environmental Sciences, Copernicus Institute, Utrecht University, PO Box 80115, 3508, TC Utrecht, the Netherlands.
authors.forename: Max
authors.initials: M
authors.lastname: Rietkerk
authors.affiliation: Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Lanzotti
mesh_terms: D066241:Carbon-13 Magnetic Resonance Spectroscopy; D018744:DNA, Plant / Q000633:toxicity*; D005110:Extracellular Space / Q000737:chemistry*; D025461:Feedback, Physiological; D006859:Hydrogen / Q000378:metabolism; D007753:Laboratories; D016014:Linear Models; D029902:Medicago / Q000378:metabolism; D008954:Models, Biological; D018515:Plant Leaves / Q000737:chemistry*; D018517:Plant Roots / Q000254:growth & development; D012987:Soil / Q000737:chemistry*; D013045:Species Specificity
chemical_list: D018744:DNA, Plant; D012987:Soil; D006859:Hydrogen
keywords: 13C nuclear magnetic resonance (NMR); activated carbon; allelopathy; autotoxicity; decomposition; litter quality