Aguado-Norese Constanza, Maldonado Jonathan E, Hodar Christian, Galvez Gabriel, Palma Daniel E, Cambiazo Verónica, Gonzalez Mauricio
Bioinformatic and Gene Expression Laboratory, INTA-Universidad de Chile, Santiago, Chile.
Millennium Institute Center for Genome Regulation, Santiago, Chile.
Environ Microbiome. 2025 Mar 11;20(1):29. doi: 10.1186/s40793-024-00661-7.
In plants, root exudates selectively influence the growth of bacteria that colonize the rhizosphere. Bacterial communities associated with root systems are involved in macro and micronutrients cycling and organic matter transformation. In particular, iron is an essential micronutrient required for the proper functioning of iron-containing enzymes in processes such as photosynthesis, respiration, biomolecule synthesis, redox homeostasis, and cell growth in plants. However, the impact of changes of iron availability on the structure and set of ecological interactions taking place in the rhizosphere remains poorly understood. In this study, field experiments were conducted to compare the effects of iron supplementation (0.1 and 0.5 mM of FeSO) on the assembly of the bacterial community of rhizosphere soil and bulk soil in a perennial grass present in the Andes steppe of Atacama Desert.
The results indicated that the difference in beta diversity between bulk soil and rhizosphere soil detected before supplementation did not persist after iron supplementation, in addition, co-occurrence networks showed a significant reduction in negative interactions among soil bacteria, mainly in rare taxa (< 0.1% relative abundance).
These observations suggest that iron availability contributes to the differentiation between bulk soil and rhizosphere bacterial communities, a process that is linked to significant changes in the relative abundance of more abundant species (> 0.1% relative abundance) and with a decrease in the negative interactions in both compartments after metal exposure. The differential effect of iron on the competition/cooperation ratio between bulk soils and the rhizosphere microbiome supports the hypothesis that the host limits the degree of cooperation that can be achieved by the bacterial community associated with an organ dedicated to nutrient absorption.
在植物中，根系分泌物会选择性地影响定殖于根际的细菌生长。与根系相关的细菌群落参与大量和微量营养元素的循环以及有机质的转化。特别是，铁是一种必需的微量营养元素，在光合作用、呼吸作用、生物分子合成、氧化还原稳态以及植物细胞生长等过程中，含铁酶的正常功能需要铁元素。然而，铁有效性的变化对根际发生的生态相互作用的结构和组合的影响仍知之甚少。在本研究中，进行了田间试验，以比较在阿塔卡马沙漠安第斯草原的一种多年生草本植物中，铁补充剂（0.1和0.5 mM的硫酸亚铁）对根际土壤和非根际土壤细菌群落组装的影响。
结果表明，补充铁之前检测到的非根际土壤和根际土壤之间的β多样性差异在补充铁之后不再持续，此外，共生网络显示土壤细菌之间的负相互作用显著减少，主要是在稀有分类群（相对丰度<0.1%）中。
这些观察结果表明，铁的有效性有助于非根际土壤和根际细菌群落之间的分化，这一过程与更丰富物种（相对丰度>0.1%）相对丰度的显著变化以及金属暴露后两个区室中负相互作用的减少有关。铁对非根际土壤和根际微生物组之间竞争/合作比率的差异影响支持了这样的假设，即宿主限制了与专门用于养分吸收的器官相关的细菌群落能够实现的合作程度。
