Revillini Daniel, Wilson Gail W T, Miller R Michael, Lancione Ryan, Johnson Nancy Collins
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States.
Department of Biology, University of Miami, Coral Gables, FL, United States.
Front Plant Sci. 2019 Aug 14;10:1018. doi: 10.3389/fpls.2019.01018. eCollection 2019.
Plants may actively cultivate microorganisms in their roots and rhizosphere that enhance their nutrition. To develop cropping strategies that substitute mineral fertilizers for beneficial root symbioses, we must first understand how microbial communities associated with plant roots differ among plant taxa and how they respond to fertilization. Arbuscular mycorrhizal (AM) fungi and rhizobacteria are of particular interest because they enhance nutrient availability to plants and perform a suite of nutrient cycling functions. The purpose of this experiment is to examine the root and soil microbiome in a long-term switchgrass () biofuel feedstock experiment and determine how AM fungi and rhizobacteria respond to plant diversity and soil fertility. We hypothesize that intra- and interspecific plant diversity, nitrogen fertilization (+N), and their interaction will influence the biomass and community composition of AM fungi and rhizobacteria. We further hypothesize that +N will reduce the abundance of nitrogenase-encoding nifH genes on the rhizoplane. Roots and soils were sampled from three switchgrass cultivars (Cave-in-Rock, Kanlow, Southlow) grown in monoculture, intraspecific mixture, and interspecific planting mixtures with either or diverse native tallgrass prairie species. Molecular sequencing was performed on root and soil samples, fatty acid extractions were assessed to determine microbial biomass, and quantitative polymerase chain reaction (qPCR) was performed on nifH genes from the rhizoplane. Sequence data determined core AM fungal and bacterial microbiomes and indicator taxa for plant diversity and +N treatments. We found that plant diversity and +N influenced AM fungal biomass and community structure. Across all plant diversity treatments, +N reduced the biomass of AM fungi and nifH gene abundance by more than 40%. The AM fungal genus was an indicator for +N, with relative abundance significantly greater under +N and in monoculture treatments. Community composition of rhizobacteria was influenced by plant diversity but not by +N. and were the dominant bacterial phyla in both roots and soils. Our findings provide evidence that soil fertility and plant diversity structure the root and soil microbiome. Optimization of soil communities for switchgrass production must take into account differences among cultivars and their unique responses to shifts in soil fertility.
植物可能会积极培育其根系和根际中的微生物，这些微生物能增强它们的营养。为了制定用有益的根系共生关系替代矿物肥料的种植策略，我们必须首先了解与植物根系相关的微生物群落在不同植物类群之间是如何不同的，以及它们对施肥的反应。丛枝菌根（AM）真菌和根际细菌特别受关注，因为它们能提高植物对养分的可利用性，并执行一系列养分循环功能。本实验的目的是在一个长期的柳枝稷（）生物燃料原料实验中研究根系和土壤微生物组，并确定AM真菌和根际细菌对植物多样性和土壤肥力的反应。我们假设种内和种间植物多样性、施氮（+N）及其相互作用将影响AM真菌和根际细菌的生物量和群落组成。我们进一步假设+N会降低根表上编码固氮酶的nifH基因的丰度。从三种柳枝稷品种（Cave-in-Rock、Kanlow、Southlow）的根系和土壤中取样，这些品种分别以单一栽培、种内混合和种间种植混合物的形式种植，种间种植混合物中要么是 要么是多种本地高草草原物种。对根系和土壤样本进行分子测序，评估脂肪酸提取物以确定微生物生物量，并对根表的nifH基因进行定量聚合酶链反应（qPCR）。序列数据确定了核心AM真菌和细菌微生物组以及植物多样性和+N处理的指示类群。我们发现植物多样性和+N影响了AM真菌的生物量和群落结构。在所有植物多样性处理中，+N使AM真菌的生物量和nifH基因丰度降低了40%以上。AM真菌属 是+N的一个指示属，在+N处理和单一栽培处理下相对丰度显著更高。根际细菌的群落组成受植物多样性影响，但不受+N影响。 和 是根和土壤中的主要细菌门。我们的研究结果提供了证据，表明土壤肥力和植物多样性构成了根系和土壤微生物组。为柳枝稷生产优化土壤群落必须考虑品种之间的差异及其对土壤肥力变化的独特反应。
