Comparative microbial community analysis of Oreocharis mileensis

Plants dynamically interact with their microbiomes through phytohormonal signaling and defense responses, shaping microbial diversity and ecosystem function. While resurrection plants host growth-promoting microbes, prior studies on different resurrection plants have been limited to localized sampling, potentially underestimating microbial diversity. We analyzed bacterial and fungal communities across five Oreocharis mileensis populations, a potential ornamental resurrection plant, to determine: population-level microbiome differences or affinity, potential microorganisms that help during desiccation of the plant and their conservation across populations. We found that microbial composition was strongly influenced by compartment (bulk soil, rhizosphere, endosphere) but exhibited only moderate drought-induced changes, suggesting O. mileensis maintains a stable microbiome under stress. Core phyla (e.g., Proteobacteria, Actinobacteriota, Ascomycota) were conserved across populations, but genus-level core taxa relatively varied, reflecting niche specialization. Drought increased alpha diversity while reducing beta diversity in bacteria, indicating homogenization driven by stress-tolerant taxa like Actinobacteriota. Fungal responses differed, with increased beta diversity suggesting drought-enhanced compositional turnover. Key bacterial genera (e.g., Burkholderia-Caballeronia-Paraburkholderia, Bacillus, Rhizobium) dominated hydrated states, while drought enriched Actinobacteria (Microlunatus, Rubrobacter) or other drought resistant taxa. Fungal communities shifted from saprotroph-dominated hydrated states to symbiotic taxa (e.g., Paraboeremia, Helotiales) under drought. Functional profiling revealed compartment-specific metabolic specialization, with drought enriching stress-response pathways (e.g., secondary metabolite biosynthesis, signal transduction). These findings demonstrate that O. mileensis microbiomes are structured by compartmental filtering and exhibit drought-driven functional plasticity, with conserved stress-adapted taxa potentially supporting host resilience. This study expands our understanding of microbiome assembly in resurrection plants and highlights candidates for microbiome engineering to enhance crop stress tolerance.

植物通过植物激素信号转导（phytohormonal signaling）与防御响应（defense responses），动态地与其微生物组（microbiome）发生相互作用，进而塑造微生物多样性与生态系统功能。尽管复苏植物（resurrection plant）可定殖促生长微生物，但此前针对不同复苏植物的研究多局限于局域采样，这可能会低估微生物多样性。本研究以一种极具观赏潜力的云南马铃苣苔（Oreocharis mileensis）的5个种群为研究对象，对其细菌与真菌群落展开分析，旨在明确种群水平的微生物组差异或类群亲和性、可帮助植物抵御脱水胁迫的潜在微生物类群，以及这些类群在不同种群间的保守性。研究发现，微生物群落组成显著受生境分区（非根际土（bulk soil）、根际（rhizosphere）、内生境（endosphere））的影响，但仅表现出中等程度的干旱诱导变化，这表明云南马铃苣苔在胁迫环境下能够维持稳定的微生物组。核心菌门（如变形菌门（Proteobacteria）、放线菌门（Actinobacteriota）、子囊菌门（Ascomycota））在各种群间均保持保守，但属水平的核心类群相对多变，这反映了生态位特化现象。干旱胁迫可提升细菌的α多样性（alpha diversity），同时降低其β多样性（beta diversity），这表明由耐胁迫类群（如放线菌门（Actinobacteriota））所驱动的群落均质化过程。真菌群落的响应则有所不同：其β多样性有所提升，暗示干旱胁迫促进了群落组成的周转。在水分充足状态下，关键细菌属（如伯克霍尔德氏菌-卡瓦隆氏菌-副伯克霍尔德氏菌属（Burkholderia-Caballeronia-Paraburkholderia）、芽孢杆菌属（Bacillus）、根瘤菌属（Rhizobium））占据群落主导地位；而干旱胁迫则富集了放线菌门（Microlunatus、Rubrobacter）及其他耐旱类群。干旱胁迫下，真菌群落从以腐生营养型（saprotroph）为主的水分充足状态，转变为以共生类群（symbiotic taxa）（如副圆孔霉属（Paraboeremia）、柔膜菌目（Helotiales））为主的状态。功能预测分析显示，微生物组存在生境分区特异性的代谢特化，且干旱胁迫会富集胁迫响应通路（如次生代谢产物生物合成（secondary metabolite biosynthesis）、信号转导（signal transduction））。上述研究结果表明，云南马铃苣苔的微生物组由生境分区过滤作用所塑造，并表现出干旱驱动的功能可塑性；保守存在的耐旱适配类群或可助力宿主提升抗逆能力。本研究拓展了学界对复苏植物微生物组组装机制的认知，并为通过微生物组工程（microbiome engineering）提升作物抗逆性（crop stress tolerance）提供了候选靶点。