Essarioui Adil, LeBlanc Nicholas, Kistler Harold C, Kinkel Linda L
Department of Plant Pathology, University of Minnesota, Minneapolis, MN, USA.
National Institute of Agronomic Research, Regional Center of Errachidia, Errachidia, Morocco.
Microb Ecol. 2017 Jul;74(1):157-167. doi: 10.1007/s00248-016-0907-5. Epub 2017 Jan 5.
Plant community characteristics impact rhizosphere Streptomyces nutrient competition and antagonistic capacities. However, the effects of Streptomyces on, and their responses to, coexisting microorganisms as a function of plant host or plant species richness have received little attention. In this work, we characterized antagonistic activities and nutrient use among Streptomyces and Fusarium from the rhizosphere of Andropogon gerardii (Ag) and Lespedeza capitata (Lc) plants growing in communities of 1 (monoculture) or 16 (polyculture) plant species. Streptomyces from monoculture were more antagonistic against Fusarium than those from polyculture. In contrast, Fusarium isolates from polyculture had greater inhibitory capacities against Streptomyces than isolates from monoculture. Although Fusarium isolates had on average greater niche widths, the collection of Streptomyces isolates in total used a greater diversity of nutrients for growth. Plant richness, but not plant host, influenced the potential for resource competition between the two taxa. Fusarium isolates had greater niche overlap with Streptomyces in monoculture than polyculture, suggesting greater potential for Fusarium to competitively challenge Streptomyces in monoculture plant communities. In contrast, Streptomyces had greater niche overlap with Fusarium in polyculture than monoculture, suggesting that Fusarium experiences greater resource competition with Streptomyces in polyculture than monoculture. These patterns of competitive and inhibitory phenotypes among Streptomyces and Fusarium populations are consistent with selection for Fusarium-antagonistic Streptomyces populations in the presence of strong Fusarium resource competition in plant monocultures. Similarly, these results suggest selection for Streptomyces-inhibitory Fusarium populations in the presence of strong Streptomyces resource competition in more diverse plant communities. Thus, landscape-scale variation in plant species richness may be critical to mediating the coevolutionary dynamics and selective trajectories for inhibitory and nutrient use phenotypes among Streptomyces and Fusarium populations in soil, with significant implications for microbial community functional characteristics.
植物群落特征影响根际链霉菌的养分竞争和拮抗能力。然而，作为植物宿主或植物物种丰富度的函数，链霉菌对共存微生物的影响及其对共存微生物的反应很少受到关注。在这项研究中，我们表征了生长在1种（单作）或16种（混作）植物群落中的糙毛须芒草（Ag）和头状胡枝子（Lc）植物根际链霉菌和镰刀菌之间的拮抗活性和养分利用情况。单作中的链霉菌比混作中的链霉菌对镰刀菌的拮抗作用更强。相比之下，混作中的镰刀菌分离株比单作中的分离株对链霉菌的抑制能力更强。虽然镰刀菌分离株的生态位宽度平均更大，但链霉菌分离株总体上利用了更多样化的养分来生长。植物丰富度而非植物宿主影响了这两个分类群之间资源竞争的潜力。镰刀菌分离株在单作中与链霉菌的生态位重叠比混作中更大，这表明镰刀菌在单作植物群落中竞争性挑战链霉菌的潜力更大。相比之下，链霉菌在混作中与镰刀菌的生态位重叠比单作中更大，这表明镰刀菌在混作中比单作中与链霉菌经历更大的资源竞争。链霉菌和镰刀菌种群之间这些竞争和抑制表型的模式与在植物单作中存在强烈的镰刀菌资源竞争时选择抗镰刀菌的链霉菌种群一致。同样，这些结果表明在更多样化的植物群落中存在强烈的链霉菌资源竞争时选择抑制链霉菌的镰刀菌种群。因此，植物物种丰富度在景观尺度上的变化可能对于介导土壤中链霉菌和镰刀菌种群之间抑制和养分利用表型的协同进化动态和选择轨迹至关重要，这对微生物群落功能特征具有重要意义。
