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.

整个土壤生物群落对植物的影响是复杂的互惠生和病原体之间正向和负向相互作用的结果。但是，很少有实验评估整个土壤生物群落对植物生长和抗病性的综合影响。我们对14种杜鹃花种进行了析因温室实验，该种杜鹃花在有或没有活的同种土壤生物区系的情况下生长，有无疾病疫霉菌（Phytophthora cinnamomi）。我们测试了预测，即整个土壤生物群落的存在会影响疾病存在下的生存。我们还探讨了整个系统发育中与疾病易感性相关的功能性状相关性。与无菌土壤相比，存在土壤生物区系可以在存在疾病的情况下提高存活率，并且这种影响的方向与四个进化枝中的七个物种一致。相对于在无菌土壤中生长的植物，活性土壤生物区系的存在还显着降低了植物的生长速度并降低了茎生物量，这表明活性土壤生物区系可能会影响植物的分配策略。我们发现根茎比率较高的杜鹃花物种对疫霉菌的敏感性较低，表明水的关系影响疾病的易感性。我们的发现表明抗病性和易感性在多个进化枝中独立发生，并且整个土壤生物群落持续增强跨进化枝的抗病性，这表明土壤生物区系可能在抗病性中发挥重要作用，并可以缓解疾病引起的死亡率。