植物生态学报

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典型草原优势植物根际细菌群落多样性和功能群组成对长期放牧的响应机制

崔冬晴1,田晨2,宋慧敏3,鲁小名3,杨培志1,白永飞4,田建卿3   

  1. 1. 西北农林科技大学
    2. 西北农林科技大学草业与草原学院
    3. 中国科学院植物研究所
    4. 中国科学院植物研究所植被与环境变化国家重点实验室
  • 收稿日期:2024-12-02 修回日期:2025-01-10 发布日期:2025-01-20
  • 通讯作者: 田建卿

The Response Mechanisms of Rhizosphere Bacterial Community Diversity and Functional Groups Composition of Dominant Plants in Typical Grasslands to Long-term Grazing

Dong-Qing CUI1,Chen TIAN2,Huiming Song3,Xiaoming Lu4,Pei-Zhi YANG5,Yong-Fei BAI6,Jian-Qing TIAN7   

  1. 1. Northwest A&F University
    2. College of Grassland Agriculture, Northwest A&F University
    3. Institude of Botany,The Chinese Academy of Science
    4. Institude of Botany,The Chinese Academy of Sciences
    5. Northwest A & F University
    6.
    7. Institute of botany, CAS
  • Received:2024-12-02 Revised:2025-01-10
  • Contact: Jian-Qing TIAN

摘要: 【目的】长期放牧深刻影响草地生态系统中植物生长发育的外部环境,植物通过与根际微生物的相互作用来适应环境变化。然而,目前关于放牧如何影响草地不同生存策略植物根际微生物多样性的研究十分有限。【方法】本研究依托内蒙古典型草原长期放牧实验平台,选取优势植物大针茅(Stipa grandis)和糙隐子草(Cleistogenes squarrosa)作为研究对象,利用高通量测序技术探讨不同放牧强度(对照,轻度:1.5 sheep·hm–2,中度:4.5 sheep·hm–2,重度:7.5 sheep·hm–2)下植物根际细菌多样性变化趋势,解析两种优势植物根际细菌的响应差异,及其与植物功能性状的内在联系。【主要结果】结果表明:(1)重度放牧显著降低大针茅根际细菌丰富度(8.97%)和Chao1指数(9.48%),但对糙隐子草根际细菌α多样性无显著影响,且大针茅根际细菌α多样性显著低于糙隐子草;此外,重度放牧显著改变了两种植物根际细菌的群落组成,其中大针茅的变化幅度显著大于糙隐子草。(2)随着放牧强度增加,大针茅富集了较多的根际促生菌和生物防治菌,而糙隐子草则主要富集了根际促生菌。(3)大针茅根际细菌群落多样性和功能菌群相对丰度的变化与其较高的根系直径、较低的比叶面积和比根长等代表避牧和资源保守策略的功能性状显著相关;而糙隐子草的根际细菌群落变化则与其较高的地上生物量碳氮比和较高的比叶面积等代表耐牧和资源消耗策略的功能性状显著相关。综上,本研究表明,不同优势植物根际细菌群落对放牧压力的响应与其生存策略密切相关,丰富了我们对长期放牧背景下植物与根际微生物群落协同适应机制的理解。

关键词: 放牧强度, 优势植物, 根际细菌, 植物功能性状, 微生物功能群

Abstract: Aims Long-term grazing profoundly affects the external environment for plant growth and development in grassland ecosystems, and plants adapt to environmental changes through interactions with rhizosphere microbes. However, there is limited research on how grazing affects the rhizosphere microbial diversity of plants with different survival strategies in grasslands. Methods In this study, based on the long-term grazing experimental platform of typical grasslands in Inner Mongolia, we selected the dominant plant species Stipa grandis and Cleistogenes squarrosa as research subjects. Using high-throughput sequencing technology, we explored the trends in rhizosphere bacterial diversity under different grazing intensities (control, light: 1.5 sheep·hm–2, moderate: 4.5 sheep·hm–2, and heavy: 7.5 sheep·hm–2), and analyzed the differences in the responses of two dominant plant rhizospheric bacteria and their intrinsic connection with plant functional traits. Important findings The results showed that: (1) Heavy grazing significantly reduced the rhizosphere bacterial richness (8.97%) and Chao1 index (9.48%) in Stipa grandis, but had no significant effect on the rhizosphere bacterial α-diversity of Cleistogenes squarrosa. Additionally, the α-diversity of Stipa grandis was significantly lower than that of Cleistogenes squarrosa. Moreover, heavy grazing significantly altered the bacterial community composition of both plant species, with the change being more pronounced in Stipa grandis than in Cleistogenes squarrosa. (2) As grazing intensity increased, Stipa grandis was enriched with both plant growth promoting rhizobacteria and biocontrol agents, Cleistogenes squarrosa whereas was primarily enriched with plant growth promoting rhizobacteria. (3) Changes in the diversity and relative abundance of rhizosphere bacterial communities in Stipa grandis were significantly correlated with its larger root diameter, lower specific leaf area, and lower specific root length, which reflect grazing avoidance and resource-conserving strategies. In contrast, changes in the bacterial communities of Cleistogenes squarrosa were significantly correlated with its higher C/N ratio in aboveground biomass and larger specific leaf area, which reflect grazing tolerance and resource-consuming strategies. In conclusion, this study demonstrated that the responses of rhizosphere bacterial communities in different dominant plant species to grazing pressure are closely related to their survival strategies, enriching our understanding of the synergistic adaptations between plants and rhizosphere microbial communities in the context of long-term grazing.

Key words: Grazing Intensity, Dominant Plants, Rhizosphere Bacteria, Plant Functional Traits, Microbial Functional Groups