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SummaryPlant-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.

Artichoke, Cynaracardunculus, is a dietary and medicinal plant species with a long tradition of use dating back to the ancient Egyptians, Greeks, and Romans. It comprises the globe artichoke, C. cardunculus subsp. scolymus, the cultivated cardoon, C. cardunculus subsp. altilis, and the wild cardoon, C. cardunculus subsp. sylvestris. The edible part of the plant is limited to the fleshy leaves (bracts) and receptacle of a large immature inflorescence, named capitulum or head, that has been shown to be a rich source of bioactive compds. On the other hand, leaves, external bracts and stems discarded by the artichoke processing industry corresponding to about 80-85 % of the total biomass of the plant, represent a suitable potential source of food additives and nutraceuticals. Nutritional and pharmacol. properties of artichoke heads and leaves are attributed mainly to polyphenolic compds. and inulin present at high concn. Other classes of chem. compds., including flavonoids, anthocyanins, sesquiterpenes, and triterpenes have been also found in the plant at lower amts. This review, after a general historical, phytogeog., and ethnobotanical overview, summarizes the current knowledge on the phytochem. and pharmacol. properties of this plant, with special emphasis on the agronomical and nutritional importance of the plant and to the methods of anal., including the recently developed metabolomic studies. [on SciFinder(R)

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