Mazzoleni Stefano, Bonanomi Giuliano, Incerti Guido, Chiusano Maria Luisa, Termolino Pasquale, Mingo Antonio, Senatore Mauro, Giannino Francesco, Cartenì Fabrizio, Rietkerk Max, Lanzotti Virginia
Dipartimento di Agraria, University of Naples Federico II, via Università 100, 80055, Portici (NA), Italy.
CNR-IGV, Istituto di Genetica Vegetale, via Università 133, 80055, Portici (NA), Italy.
New Phytol. 2015 Feb;205(3):1195-1210. doi: 10.1111/nph.13121. Epub 2014 Oct 29.
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.
植物-土壤负反馈（NF）被认为是影响植物群落的一个重要因素。这项工作的目的是评估凋落物的植物毒性和自毒作用对根系增殖的影响，并检验DNA是凋落物自毒作用和植物-土壤负反馈驱动因素的假设。在不同的生物测定中研究了分解凋落物的抑制作用。用核磁共振（NMR）光谱评估凋落物的生化变化。在实验室实验中测量了凋落物和土壤中DNA的积累，并评估了DNA毒性。未分解的凋落物对根系生长产生非特异性抑制，而老化的凋落物产生自毒作用。添加活性炭（AC）可消除植物毒性，但对自毒作用无效。植物毒性与已知的不稳定化感化合物有关。与核酸相关的受限碳-13 NMR信号是唯一与同种底物上根系生长呈负相关的信号。在凋落物分解和土壤历史实验中均观察到DNA积累。提取的总DNA显示出明显的物种特异性毒性。结果表明，与暴露于碎片化自身DNA相关的凋落物自毒作用普遍存在。证据还表明，积累的细胞外DNA参与了植物-土壤负反馈。需要进一步研究，以在生态系统水平上进一步探究细胞外DNA这一意外功能及其相关的细胞和分子机制。
