Harnessing biological complexity to improve food security: How do mycorrhizal networks control resource transfer and plant productivity in inter- and mono-crop model systems?

长期以来的研究传统表明，植物及其真菌共生体在土壤中相互联系的网络之间的资源交换可以增加生态系统对环境变化的适应能力。人们对利用这些植物和真菌网络的弹性建设能力来提高粮食生产管理生态系统的可持续性越来越感兴趣，但由于难以理解不同植物和真菌群落产生的复杂网络行为，特别是在压力下，这一领域的进展受到阻碍。该项目将通过结合现场实验、实验室研究和数学模型来定量表征太平洋西北地区草原和牧场系统网络中碳和氮的交换，从而应对这一挑战。在该地区，冬季较湿，夏季较干，季节性日益严重，预计将导致草原和牧场生产力下降。这是一个需要解决的重大问题，因为西北草原和牧场系统目前维持着100多万头肉牛，而小牛的生产成本预计将增加，以抵消干旱的影响。该项目将检验这样一种假设，即植物物种特征的变化，由本地物种覆盖减少而有利于外来草类引起，将反映在植物-真菌网络的功能中。调节干旱反应的网络行为将被测量，以量化植物和土壤微生物群落之间复杂但可预测的相互作用。该项目将评估植物和土壤群落对520公里纬度梯度上实验施加的干旱的敏感性。关于根真菌网络在维持多样化草原和低多样性牧场生产力方面的作用的一般假设将得到检验，以解决该地区和其他地方类似系统的可持续性面临的主要挑战。具体来说，拟议的任务将确定植物和真菌物种，最好地保持初级生产力，植物水分利用效率，促进碳和氮交换在逆境下的社区。这些知识将用于确定物种组成和土壤资源可用性的阈值，超过这些阈值就需要进行干预，以防止生物多样性丧失和对干旱的适应能力。利用稳定同位素标记实验监测菌根网络介导的碳和氮的转移或保留的变化，以确定种间连通性是否以及如何增加群落在压力下的恢复力和生产力。跨纬度梯度的复制嵌套设计将用于表征可以简化的网络行为，以改善本地和管理系统中的特定间连接和资源转移。不同植物物种和真菌之间的被动和主动资源运输将通过DNA序列的稳定同位素探测来区分，并用于开发影响共同菌根网络组成和功能的互惠和竞争相互作用的空间明确模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A long tradition of research suggests that exchange of resources between plants and their fungal symbionts in linked networks in the soil can increase the resilience of ecosystems to environmental change. There is growing interest in harnessing the resilience building power of these networks of plant and fungi to enhance the sustainability of ecosystems that are managed for food production, but progress in this field has been hindered by difficulties in understanding complex network behaviors that arise from different plant and fungal communities, especially when under stress. This project will address this challenge by combining field experiments, laboratory studies, and mathematical models to quantitatively characterize the exchange of carbon and nitrogen in networks of prairie and pasture systems across the Pacific Northwest. In this region, increasingly severe seasonality, characterized by wetter winters and drier summers, are expected to cause declines in prairie and pasture productivity. This is a significant problem to address because Northwest prairie and pasture systems currently sustain more than 1 million beef cows and cow-calf production costs are expected to increase to offset the effects of drought. The project will test the hypothesis that variation in plant species traits, caused by a decline in native species cover in favor of exotic grasses, will be reflected in the plant-fungi network's function. Network behaviors that regulate responses to drought will be measured to quantify interactions between plants and soil microbial communities that are complex, yet predictable. The project will assess plant and soil community sensitivity to experimentally imposed drought across a 520 kilometer latitudinal gradient. General hypotheses pertaining to the role of root-fungal networks in maintaining diverse prairie and low-diversity pasture productivity will be tested to address a major challenge for sustainability in the region and in similar systems elsewhere. Specifically, the proposed tasks will identify plant and fungal species that best maintain primary productivity, plant water-use efficiency, and foster carbon and nitrogen exchange in communities under stress. This knowledge will be used to determine thresholds of species composition and soil resource availability beyond which intervention is needed to prevent loss of biodiversity and resilience to drought. Alterations of mycorrhizal networks-mediated transfer or retention of carbon and nitrogen will be monitored using stable isotope labeling experiments to determine whether and how inter-specific connectivity increases community resilience and productivity under stress. A replicated nested design across a latitudinal gradient will be used to characterize network behaviors that can be simplified to improve inter-specific connectivity and resource transfer in native and managed systems. Passive and active resource transport among different plant species and fungi will be distinguished through stable isotope probing of DNA sequences and used to develop a spatially-explicit model for the scaling of mutualistic and competitive interactions affecting composition and function of common mycorrhizal networks.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.