Easterday Casey A, Kendig Amy E, Lacroix Christelle, Seabloom Eric W, Borer Elizabeth T
Department of Ecology, Evolution, and Behavior University of Minnesota St. Paul Minnesota USA.
Present address: Carlson School of Management University of Minnesota Minneapolis Minnesota USA.
Ecol Evol. 2022 Jan 15;12(1):e8450. doi: 10.1002/ece3.8450. eCollection 2022 Jan.
Host nutrient supply can mediate host-pathogen and pathogen-pathogen interactions. In terrestrial systems, plant nutrient supply is mediated by soil microbes, suggesting a potential role of soil microbes in plant diseases beyond soil-borne pathogens and induced plant defenses. Long-term nitrogen (N) enrichment can shift pathogenic and nonpathogenic soil microbial community composition and function, but it is unclear if these shifts affect plant-pathogen and pathogen-pathogen interactions. In a growth chamber experiment, we tested the effect of long-term N enrichment on infection by Barley Yellow Dwarf Virus (BYDV-PAV) and Cereal Yellow Dwarf Virus (CYDV-RPV), aphid-vectored RNA viruses, in a grass host. We inoculated sterilized growing medium with soil collected from a long-term N enrichment experiment (ambient, low, and high N soil treatments) to isolate effects mediated by the soil microbial community. We crossed soil treatments with a N supply treatment (low, high) and virus inoculation treatment (mock-, singly-, and co-inoculated) to evaluate the effects of long-term N enrichment on plant-pathogen and pathogen-pathogen interactions, as mediated by N availability. We measured the proportion of plants infected (i.e., incidence), plant biomass, and leaf chlorophyll content. BYDV-PAV incidence (0.96) declined with low N soil (to 0.46), high N supply (to 0.61), and co-inoculation (to 0.32). Low N soil mediated the effect of N supply on BYDV-PAV: instead of N supply reducing BYDV-PAV incidence, the incidence increased. Additionally, ambient and low N soil ameliorated the negative effect of co-inoculation on BYDV-PAV incidence. BYDV-PAV infection only reduced chlorophyll when plants were grown with low N supply and ambient N soil. There were no significant effects of long-term N soil on CYDV-RPV incidence. Soil inoculant with different levels of long-term N enrichment had different effects on host-pathogen and pathogen-pathogen interactions, suggesting that shifts in soil microbial communities with long-term N enrichment may mediate disease dynamics.
宿主的养分供应能够介导宿主与病原体以及病原体与病原体之间的相互作用。在陆地生态系统中，植物的养分供应由土壤微生物介导，这表明土壤微生物在植物病害中可能发挥着潜在作用，其作用范围超出了土传病原体和诱导植物防御的范畴。长期的氮（N）富集能够改变致病和非致病土壤微生物群落的组成与功能，但目前尚不清楚这些变化是否会影响植物与病原体以及病原体与病原体之间的相互作用。在一项生长室实验中，我们测试了长期氮富集对禾本科宿主感染大麦黄矮病毒（BYDV - PAV）和谷类黄矮病毒（CYDV - RPV）的影响，这两种病毒均由蚜虫传播，属于RNA病毒。我们用从长期氮富集实验（对照、低氮和高氮土壤处理）中收集的土壤接种灭菌的生长培养基，以分离由土壤微生物群落介导的影响。我们将土壤处理与氮供应处理（低、高）以及病毒接种处理（模拟接种、单接种和共接种）进行交叉实验，以评估长期氮富集对植物与病原体以及病原体与病原体之间相互作用的影响，这种影响由氮的有效性介导。我们测量了受感染植物的比例（即发病率）、植物生物量和叶片叶绿素含量。BYDV - PAV的发病率（0.96）在低氮土壤（降至0.46）、高氮供应（降至0.61）和共接种（降至0.32）的情况下下降。低氮土壤介导了氮供应对BYDV - PAV的影响：不是氮供应降低了BYDV - PAV的发病率，而是发病率增加了。此外，对照和低氮土壤减轻了共接种对BYDV - PAV发病率的负面影响。只有当植物在低氮供应和对照氮土壤中生长时，BYDV - PAV感染才会降低叶绿素含量。长期氮土壤对CYDV - RPV发病率没有显著影响。不同长期氮富集水平的土壤接种剂对宿主与病原体以及病原体与病原体之间的相互作用有不同影响，这表明长期氮富集导致的土壤微生物群落变化可能介导病害动态。
