低秋眠耐寒苜蓿根系微生物组装特征及其品种间差异

doi:10.11686/cyxb2025190

摘要/Abstract

摘要：

植物生长与抗逆表现依赖于植物根与共生微生物之间的有益互作。低秋眠级苜蓿在短日照和低温条件下适应性强，但其根系相关微生物组装特征及其品种间差异尚不明确。本研究依托甘肃甘南野外试验站，种植4种低秋眠级苜蓿品种：兰苜1号、公农1号、金皇后（前3种均为紫花苜蓿）和甘农1号（杂花苜蓿）。利用16S rRNA基因扩增子测序，系统分析4个苜蓿品种根际与根内细菌群落特征及组装机制。结果表明，苜蓿根际细菌群落物种多样性显著高于根内，不同品种之间根系细菌群落结构同样差异显著。与其他品种相比，新型耐寒品系兰苜1号在根际特异性富集了链嗜酸菌属，并在一定程度上提高了根系富集的细菌群落物种多样性，增强了微生物共现网络的复杂性和连通性。群落构建过程分析表明，所有品种的根际和根内细菌群落组装主要受到异质性选择（42%~55%）和匀质性选择（56%~83%）过程影响，其中兰苜1号、公农1号和甘农1号品种根系细菌群落相比于金皇后受到更大程度的确定性选择过程影响。本研究揭示了低秋眠级苜蓿根际与根内微生物群落的组装模式及品种间差异，为调控植物微生物组以提升寒区牧草适应性提供理论依据。

关键词: 多年生苜蓿, 根际, 根内, 品种差异, 共发生网络, 群落组装

Abstract:

Plant growth and stress resilience rely on beneficial interactions between roots and symbiotic microorganisms. Low fall dormancy alfalfa （Medicago sativa） varieties exhibit strong adaptability to short-day and low-temperature conditions， but the characteristics of their root-associated microbial assemblies and cultivar-specific variations remain unclear. In this study， four low fall dormancy alfalfa cultivars-‘Lanmu No. 1’， ‘Gongnong No. 1’， ‘Golden empress’ （all M. sativa）， and ‘Gannong No. 1’ （Medicago lupulina） -were cultivated at a field experimental station in Gannan， Gansu Province. Using 16S rRNA gene amplicon sequencing， we analyzed rhizospheric and endophytic bacterial communities and their assembly mechanisms. The results show that bacterial alpha diversity was significantly higher in the rhizosphere than in endosphere， with distinct community structures observed among cultivars. Compared with the other cultivars， the cold-tolerant cultivar ‘Lanmu No. 1’ was uniquely enriched with Streptacidiphilus in the rhizosphere， showed increased endophytic bacterial diversity， and greater complexity and connectivity of microbial co-occurrence networks. Analysis of community assembly processes revealed that both rhizospheric and root endophytic communities were primarily governed by heterogeneous selection （42%-55%） and homogeneous selection （56%-83%）. Notably， deterministic selection had a stronger influence on root-associated communities in ‘Lanmu No. 1’， ‘Gongnong No. 1’， and ‘Gannong No. 1’ than in ‘Golden empress’. This study elucidates the assembly patterns and cultivar-driven divergence of root-associated microbiomes in low fall dormancy alfalfa. These results provide a theoretical foundation for microbiome manipulation to improve forage crop adaptability in cold， high-altitude regions.

Key words: perennial alfalfa, rhizosphere, endosphere, variety differences, co-occurrence network, community assembly

王召明, 郑丽娜, 张跃华, 赵韦, 陈翔, 贾振宇. 低秋眠耐寒苜蓿根系微生物组装特征及其品种间差异[J]. 草业学报, 2026, 35(2): 195-207.

Zhao-ming WANG, Li-na ZHENG, Yue-hua ZHANG, Wei ZHAO, Xiang CHEN, Zhen-yu JIA. Bacterial community assembly in the rhizosphere and endosphere of different perennial alfalfa varieties with low fall dormancy rates[J]. Acta Prataculturae Sinica, 2026, 35(2): 195-207.

图/表 7

图1 甘肃省甘南野外试验设置（a、b）及样品采集处理流程（c、d）

Fig.1 Field experiment setup （a， b） and sample collection and processing （c， d） in Gannan， Gansu Province

图2 不同苜蓿品种的根际与根内微生物多样性差异（a、b、c）及门水平物种组成（d）不同苜蓿品种包括：甘农1号（Gan1）、公农1号（Gong1）、金皇后（GE）与兰苜1号（Lan1）。下同。Different alfalfa varieties include： Gannong No.1 （Gan1）， Gongnong No.1 （Gong1）， Golden empress （GE） and Lanmu No.1 （Lan1）. The same below.

Fig.2 Differences in rhizosphere and endosphere microbial richness （a， b， c） and phylum level species composition （d） among different alfalfa varieties

图3 不同苜蓿品种的根际与根内微生物beta多样性分析（a）：根际与根内细菌群落的整体差异 Overall differences in rhizosphere vs endosphere bacterial communities；（b）：品种间根际细菌群落的差异 Differences in rhizosphere bacterial communities among varieties；（c）：品种间根内细菌群落的差异 Differences in endophytic bacterial communities among varieties.

Fig. 3 Beta diversity of rhizosphere and endophytic microorganisms in different alfalfa varieties

图4 不同苜蓿品种的根际与根内丰度存在显著差异的微生物数量及根内富集的微生物种类（a）、（b）、（c）、（d）：不同苜蓿品种根际-根内细菌物种富集分析Enrichment analysis of rhizosphere and endosphere bacterial species in different varieties；（e）：根内富集的细菌物种的系统发育关系及其在不同苜蓿品种中的分布模式Phylogenetic relationships of bacterial species enriched in endosphere and their distribution in different varieties.

Fig.4 Number of microorganisms with significant differences in rhizosphere and endosphere abundance among alfalfa varieties and the taxonomy of microorganisms enriched in endosphere

图5 兰苜1号（Lan1）与其他品种根际微生物差异分析（a）、（b）、（c）分别是甘农1号、公农1号、金皇后与兰苜1号相比的根际细菌丰度差异分析The differences in rhizosphere bacterial abundance between Gan1 and Lan1， between Gong1 and Lan1， and between GE and Lan1， respectively；（d）：兰苜1号根际相比于其他品种富集的细菌种类数The number of bacterial species enriched in the rhizosphere of Lan1 compared to other varieties；（e）：兰苜1号根际相比于其他品种消减的细菌种类数The number of bacterial species reduced in the rhizosphere of Lan1 compared to other varieties.

Fig.5 Differential analysis of rhizosphere microorganisms between Lanmu No.1 （Lan1） and other varieties

图6 不同品种根际与根内微生物互作网络拓扑结构特征

Fig.6 The topological structures of the interaction network of rhizosphere and endophytic bacteria in different varieties

图7 不同苜蓿品种根内和根际微生物群落构建过程

Fig.7 Community assembly processes of rhizosphere and endosphere bacteria in different alfalfa varieties

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