Endophytic fungi can profoundly affect host productivity, but the underlying mechanisms of these effects are only partly understood. As the most important regulators of plant-soil feedback, root exudates can easily cause soil sickness in continuous monoculture systems by reducing certain microbes in the rhizosphere. In this study, exudates from roots colonized by the endophytic fungus Phomopsis liquidambaris significantly increased rhizosphere bacterial abundance, soil respiration, microbial biomass and enzyme activities in a long-term continuously cropped peanut soil. Further analysis revealed that P. liquidambaris-colonized root exudates clearly altered the carbon metabolism and rhizosphere bacterial diversity, which were closely correlated with changes in soil chemical properties caused by the exudates from the colonized roots. Finally, a synthetic root exudate experiment further confirmed that the root exudates derived from P. liquidambaris colonization can indeed play an important role in promoting peanut growth. Therefore, these results show that this endophytic fungus could improve the carbon metabolism and rhizosphere bacterial community in long-term monoculture soils via exudates from colonized roots, which contribute to the alleviation of soil sickness.

内生真菌可以深刻地影响宿主生产力，但这些影响的潜在机制只是部分了解。作为植物-土壤反馈的最重要调节剂，根系分泌物通过减少根际中的某些微生物，很容易在连续单一栽培系统中引起土壤病。在这项研究中，内生真菌Phomopsisliquidambaris定植的根系分泌物显着增加了长期连作花生土壤中的根际细菌丰度、土壤呼吸、微生物生物量和酶活性。进一步分析表明，P.liquidambaris-定植根系分泌物明显改变了碳代谢和根际细菌多样性，这与由定植根系分泌物引起的土壤化学性质变化密切相关。最后，合成根系分泌物实验进一步证实，来自P.liquidambaris定植的根系分泌物确实可以在促进花生生长方面发挥重要作用。因此，这些结果表明，这种内生真菌可以通过定植根系的分泌物改善长期单一栽培土壤中的碳代谢和根际细菌群落，有助于缓解土壤病。