Plant Ecology Group, University of Tübingen, Auf der Morgenstelle 5, D-72076, Tübingen, Germany.
New Phytol. 2019 Mar;221(4):2203-2212. doi: 10.1111/nph.15528. Epub 2018 Nov 9.
Plant-plant interactions are reciprocal and include effects on and response to neighbours. Distinct traits confer competitive effect and response ability, but how specific traits determine effect and response in facilitative interactions has not been studied experimentally. We utilized the model species Arabidopsis thaliana to test for trait dependence of facilitative interactions. Salt-sensitive (sos) mutants or salt-tolerant wild-types were exposed to an experimental salinity gradient with and without intraspecific neighbours and the intensity of plant-plant interactions was measured for three performance variables. We tested whether salt tolerance can predict facilitative effect and response and whether a tradeoff exists between competitive ability and tolerance to stress. Interactions shifted very clearly from negative to positive with increasing stress. Salt-sensitive genotypes were less negatively affected by competition but more dependent on facilitation than were wild-types, indicating a tradeoff between competitive ability and stress tolerance. Surprisingly, sensitive genotypes imposed stronger facilitative effects, despite being much smaller under stress, probably because they retrieved more salt from the soil. Stress tolerance defined facilitative effect and response via distinct mechanisms. We advocate more controlled experiments with model species to advance our understanding of the trait dependence of biotic interactions and their consequences for community organization.
植物-植物相互作用是相互的，包括对和对邻居的影响和响应。不同的特征赋予竞争效应和响应能力，但特定特征如何决定促进相互作用中的效应和响应尚未在实验中进行研究。我们利用模式物种拟南芥来测试促进相互作用的特征依赖性。盐敏感（sos）突变体或耐盐野生型暴露于具有和不具有种内邻居的实验盐度梯度中，并测量三个性能变量的植物-植物相互作用强度。我们测试了盐耐受性是否可以预测促进作用和响应，以及竞争能力和耐受应激之间是否存在权衡。随着胁迫的增加，相互作用从负向正向转变非常明显。盐敏感基因型受竞争的负面影响较小，但对促进的依赖性大于野生型，表明竞争能力和应激耐受性之间存在权衡。令人惊讶的是，敏感基因型尽管在压力下较小，但仍施加更强的促进作用，可能是因为它们从土壤中回收了更多的盐分。应激耐受性通过不同的机制定义了促进作用和响应。我们提倡使用模式物种进行更多的对照实验，以推进我们对生物相互作用的特征依赖性及其对群落组织的影响的理解。
