Department of Biology, Case Western Reserve University, Cleveland, OH, 44106-7080, USA.
The Holden Arboretum, 9500 Sperry Road, Kirtland, OH, 44094, USA.
Oecologia. 2021 Jan;195(1):1-12. doi: 10.1007/s00442-020-04762-1. Epub 2020 Oct 6.
The effects of whole soil biotic communities on plants is a result of positive and negative interactions from a complex suite of mutualists and pathogens. However, few experiments have evaluated the composite effects of whole soil biotic communities on plant growth and disease resistance. We conducted a factorial greenhouse experiment with 14 Rhododendron species grown with and without live conspecific soil biota and with and without the disease, Phytophthora cinnamomi. We tested the prediction that the presence of whole soil biotic communities influences survival in the presence of disease. We also explored functional trait correlations with disease susceptibility across the phylogeny. The presence of live soil biota led to higher survival in the presence of disease compared with sterilized soils, and the direction of this effect was consistent for seven species across four clades. The presence of live soil biota also significantly reduced plant growth rate and decreased shoot biomass, relative to plants grown in sterilized soil, indicating that live soil biota might influence plant allocation strategies. We found that Rhododendron species with higher Root Shoot Ratios were less susceptible to Phytophthora, suggesting that water relations influence disease susceptibility. Our findings that disease resistance and susceptibility occur independently across multiple clades and that whole soil biotic communities consistently enhance disease resistance across clades, suggest that soil biota may play an important role in disease resistance and can moderate disease-induced mortality.
土壤生物群落对植物的影响是由一系列互惠共生体和病原体的正、负相互作用所导致的。然而，很少有实验评估过土壤生物群落整体对植物生长和抗病性的综合影响。我们进行了一项在温室中进行的析因实验，有 14 种杜鹃属植物种植在有和没有活体同种土壤生物群和有和没有疾病（肉桂疫霉）的土壤中。我们验证了这样一个预测，即土壤生物群落的存在会影响植物在有疾病存在的情况下的存活。我们还探索了跨系统发育的功能性状与疾病易感性之间的相关性。与灭菌土壤相比，活体土壤生物群的存在导致了在有疾病存在的情况下更高的存活率，并且这种效应在四个分支中的七个物种中是一致的。活体土壤生物群的存在还显著降低了植物的生长速度和地上生物量，与在灭菌土壤中生长的植物相比，这表明活体土壤生物群可能影响植物的分配策略。我们发现，杜鹃属植物的根冠比越高，对肉桂疫霉的抵抗力越强，这表明水分关系会影响疾病的易感性。我们的研究结果表明，抗病性和易感性在多个分支中独立发生，而土壤生物群落则一致地增强了跨分支的抗病性，这表明土壤生物可能在抗病性中发挥重要作用，并能减轻疾病引起的死亡率。
