蚯蚓介导的土壤过程对植物生长和抗（虫）性的影响

Intensive land-use reduces soil biodiversity and restricts the functional roles of soil biota in terms of nutrient transformation and plant growth. With increasing pressures on energy consumption and environment pollution, the reduction of chemical fertilizer and pesticide becomes national target for sustainability of land-use . But the loss of soil biodiversity leads to a paradox between the promoting agricultural production and the decreasing agricultural chemicals input. The knowledge about functionality of key organism in soil ecosystem is critical for efficiently managing soil biological resources. Although the potentials of earthworm as a kind of beneficial soil ecosystem engineer in providing agricultural ecosystem services have been well-known, the effects of earthworm on plant growth and resistance against herbivores have been neglected and not mechanically understood yet so far. For example, there is knowledge gap about the interactive effects of soil environment conditions and biological factors such as soil nitrogen status and earthworm species or ecotypes. Besides, there is lack of a holistic approach to integrating plant aboveground and belowground as well as the trade-off relationships between plant growth and resistance. In particular, neither are there studies simultaneously analyzing biochemical properties and genomics of soils and plants in mechanically elucidating the earthworm effects on plant growth and resistance. Combining long-term in situ field experiment and a batch of manipulative microcosm experiments, the current project would comprehensively evaluate the response of plant growth and defenses against aboveground herbivores (Frankliniella occidentalis) affected by the indigenous endogeic earthworm species Metaphire guillelmi and epigeic earthworm species Amynthw cortices across a gradient of nitrogen input. Moreover, the mechanisms of plant growth and resistance responses to earthworm were explored through disentangling the biotic and abiotic properties worked by earthworm activity in the field experiment and through the analysis of resource allocation and defense compounds of aboveground and belowground. Taken together, our results will not only help clarify the functionality of soil fauna and inherent mechanisms, and it also guide the soil-plant holistic management practice to effectively utilize the valuable biological resources such as earthworm for sustainable agriculture with less and less reliance on agricultural chemicals.

高强度土地利用降低了土壤生物多样性，制约了土壤生物在养分转化和植物生长中的作用，阻碍了“减肥减药”生态农业进程。了解调控土壤过程的关键生物的功能，对于利用土壤生物资源具有重要意义。蚯蚓作为有益生物提高养分有效性的潜力已得到公认，但有关它对植物生长尤其是抗（虫）性的影响及机制的认识仍刚起步，如缺乏考虑土壤环境和生物因素的影响，缺少整合植物地上-地下部及生长-抗性权衡关系的系统研究。本项目基于蚯蚓接种菜地定位实验及室内调控实验等，系统评估了蚯蚓对番茄生长和对地上部害虫防御能力的影响，阐明了氮素和蚯蚓种类等调控因素对于蚯蚓作用的交互影响。在此基础上，从蚯蚓介导的土壤生物和非生物性质的变化入手，针对植物地上和地下部资源和防御物质的变化，揭示蚯蚓的影响机制。预期结果有助于全面了解土壤动物的功能和调控机制，为提升“减肥减药”潜力及将土壤生物资源纳入土壤-作物管理技术系统提供依据。

蚯蚓作为有益生物在恢复土壤功能上的潜力已得到公认，但迄今仍缺乏有关它对植物生长尤其是抗（虫）性的影响及机制的认识，特别是缺少整合植物地上-地下部及生长-抗性权衡关系的系统研究。本项目结合蚯蚓野外原位、室内调控和交叉置换实验设计，结合植物代谢物和分子转录组技术，针对植物在植食害虫影响下地上和地下部的响应及生长和防御的权衡关系，揭示蚯蚓对植物表现的影响机制。结果表明：（1）蚯蚓诱导植物通过资源-成本权衡生长和防御来抑制蓟马数量。蚯蚓促进植物茎叶水杨酸的相关基因表达和合成，通过激素拮抗抑制茉莉酸及下游防御通路的应答，使蚜虫受到蚯蚓的促进作用。（2）蚯蚓作用下的土壤生物改变了后续植物根际微生物的多样性及群落结构。其中，蚯蚓作用的土壤都增加了细菌α多样性，使细菌群落的功能向初生代谢过程富集，加强了真细菌间的联系；并进一步促进了植物地上干生物量和可溶性糖的积累，却降低了茉莉酸的含量，说明蚯蚓介导的土壤生物群落变化使植物生长-防御的权衡向生长倾斜，但有更强抵抗后续植食性胁迫的潜力。（3）高干旱胁迫时，蚯蚓通过增加抗氧化能力提高了植物抗旱性，番茄茎叶脱落酸和茉莉酸含量分别增加了43.2%和33.6%。低干旱胁迫时，蚯蚓对植物抗旱性无明显影响。干旱导致的土壤水分和养分条件变化影响着蚯蚓介导的植物抗旱性响应。在未来气候变化下土壤动物对植物生长的作用值得深入研究。（4）多功能性能够同时评估蚯蚓活动对多个生态系统过程的影响，为蚯蚓的功能提供更为客观和全面的评价。通过分析20多个生态系统多功能指标，发现蚯蚓能够维持生态系统多功能性在一个更高的水平，且主要是通过改变土壤群落功能组成，使其朝着细菌能流通道的群落发展，并且加强土壤微生物与微动物营养级之间的协同作用。本项目结果有助于全面了解土壤动物的功能调控机制，为提升“减肥减药”潜力和利用土壤生物资源的农业管理技术系统提供依据。