2022-11-03 ローレンスリバモア国立研究所(LLNL)
今回の研究で研究チームは、干ばつなどの気候変動にさらされた場合、ウイルスは宿主である微生物よりも迅速に適応することを発見した。土壌の水分が減少すると、ウイルス群集の構成が変化し、干ばつに適応した放線菌に感染すると予測される種類のウイルスがより優勢になった。
土壌における宿主とウイルスの相互作用を制約するものを解明するためには、空間と時間にわたるウイルス群集の構成と回転を知ることが必要である。研究者たちは、土壌の “ウイルス圏 “が非常に多様で、動的、活発で、空間的に構造化されていることを発見した。また、環境条件の変化、特に降雨量に迅速に反応することができるようである。
<関連情報>
- https://www.llnl.gov/news/come-rain-or-shine-viruses-live-soil
- https://www.pnas.org/doi/10.1073/pnas.2209132119
草地における土壌ウイルス集団と遺伝子型の空間的な入れ替わりと水分に対する凝集性の重なり Spatial turnover of soil viral populations and genotypes overlain by cohesive responses to moisture in grasslands
Christian Santos-Medellín, Katerina Estera-Molina, Mengting Yuan, Jennifer Pett-Ridge, Mary K. Firestone, and Joanne B. Emerson
Proceedings of the National Academy of Sciences Published:November 2, 2022
DOI:https://doi.org/10.1073/pnas.2209132119
Significance
Through infection and mortality of microbiota, viruses have myriad impacts on host metabolism, evolution, and Earth’s biogeochemical cycles. The sheer abundance of soil viruses hints at their likely importance in terrestrial ecosystems, yet the factors shaping soil viral diversity are poorly understood. Here, we show that grassland viral communities exhibited robust spatial structuring across one field, suggesting strong dispersal limitations at the local scale. Further, a shift in viral community composition accompanied a decrease in soil moisture, whereby phages predicted to infect abundant actinobacteria were enriched. Thus, despite spatial turnover, viruses responded cohesively to changing environmental conditions, suggesting the potential for a predictive understanding of soil virosphere dynamics and impacts on terrestrial processes.
Abstract
Viruses shape microbial communities, food web dynamics, and carbon and nutrient cycling in diverse ecosystems. However, little is known about the patterns and drivers of viral community composition, particularly in soil, precluding a predictive understanding of viral impacts on terrestrial habitats. To investigate soil viral community assembly processes, here we analyzed 43 soil viromes from a rainfall manipulation experiment in a Mediterranean grassland in California. We identified 5,315 viral populations (viral operational taxonomic units [vOTUs] with a representative sequence ≥10 kbp) and found that viral community composition exhibited a highly significant distance–decay relationship within the 200-m2 field site. This pattern was recapitulated by the intrapopulation microheterogeneity trends of prevalent vOTUs (detected in ≥90% of the viromes), which tended to exhibit negative correlations between spatial distance and the genomic similarity of their predominant allelic variants. Although significant spatial structuring was also observed in the bacterial and archaeal communities, the signal was dampened relative to the viromes, suggesting differences in local assembly drivers for viruses and prokaryotes and/or differences in the temporal scales captured by viromes and total DNA. Despite the overwhelming spatial signal, evidence for environmental filtering was revealed in a protein-sharing network analysis, wherein a group of related vOTUs predicted to infect actinobacteria was shown to be significantly enriched in low-moisture samples distributed throughout the field. Overall, our results indicate a highly diverse, dynamic, active, and spatially structured soil virosphere capable of rapid responses to changing environmental conditions.