Native root-associated bacteria rescue a plant from a sudden-wilt disease that emerged during continuous cropping
Native root-associated bacteria rescue a plant from a sudden-wilt disease that emerged during continuous cropping
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DOI：
10.1073/pnas.1505765112
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发表时间：
2015-09-08
影响因子：
11.1
通讯作者：
Baldwin, Ian T.
中科院分区：
文献类型：
--
作者：
Santhanam, Rakesh;Van Thi Luu;Baldwin, Ian T.
植物维持微生物的联系，其功能在很大程度上仍是未知的。在过去的15年中，我们在植物原生栖息地的试验田中种植了一年生的火灾后烟草Nicotiana attenuata，在过去的8年中，死于突然枯萎病的植物数量增加，导致作物歉收。无意中，我们概括了与这种本地植物连作有关的病原体积累的常见农业困境。植物遭受突然的组织塌陷和黑根，症状类似于镰刀菌-互花菌病复合体，最近在附近的本地种群中表现出特征，并发展成为N. attenuata的离体病理系统。利用这种体外疾病系统，在田间进一步测试了不同的保护策略（杀菌剂和用本地根相关细菌和真菌分离物接种）以及生物炭土壤改良剂。在两个大田试验中，对900多株植物进行了田间试验，结果表明，接种本地细菌分离物的混合物可显著降低感染地块的疾病发病率和死亡率，而不会影响生长、对食草动物的抗性，也不会影响已知介导对本地食草动物抗性的32种防御和信号代谢产物。随后一年的试验表明，一个由五种细菌组成的核心联合体对减少疾病至关重要。这个联合体，而不是这种植物通常在发芽时从本地种子库中招募的根相关细菌群落的单个成员，提供了对真菌疾病的持久抵抗力，表明本地植物与原核生物发展了机会性互惠关系，解决了环境依赖的生态问题。
Plants maintain microbial associations whose functions remain largely unknown. For the past 15 y, we have planted the annual postfire tobacco Nicotiana attenuata into an experimental field plot in the plant's native habitat, and for the last 8 y the number of plants dying from a sudden wilt disease has increased, leading to crop failure. Inadvertently we had recapitulated the common agricultural dilemma of pathogen buildup associated with continuous cropping for this native plant. Plants suffered sudden tissue collapse and black roots, symptoms similar to a Fusarium-Alternaria disease complex, recently characterized in a nearby native population and developed into an in vitro pathosystem for N. attenuata. With this in vitro disease system, different protection strategies (fungicide and inoculations with native root-associated bacterial and fungal isolates), together with a biochar soil amendment, were tested further in the field. A field trial with more than 900 plants in two field plots revealed that inoculation with a mixture of native bacterial isolates significantly reduced disease incidence and mortality in the infected field plot without influencing growth, herbivore resistance, or 32 defense and signaling metabolites known to mediate resistance against native herbivores. Tests in a subsequent year revealed that a core consortium of five bacteria was essential for disease reduction. This consortium, but not individual members of the root-associated bacteria community which this plant normally recruits during germination from native seed banks, provides enduring resistance against fungal diseases, demonstrating that native plants develop opportunistic mutualisms with prokaryotes that solve context-dependent ecological problems.