Supplementary Tables of the manuscript: <b>Nitrogen starvation response in hornworts and liverworts provides little evidence for complex priming to the </b><b>cyanobiont</b>

Mutualistic plant-microbe symbiotic interactions are thought to have evolved from a loose association between host plants and microbes when nutrients are limited. Therefore, the molecular network enabling intimate mutualistic plant-microbe symbioses may have evolved from a nutrient starvation response shared by all land plants. While the molecular link between nutrient status and symbiotic interaction is well-established, it remains poorly understood in some systems. This is especially true for the symbiotic associations between plants and cyanobacteria.     To test the conservation of the starvation network across land plants as well as to investigate the link between nutrient starvation and symbiosis initiation in the plant-cyanobacteria symbiosis, here we explore the transcriptional responses to nutrient starvation in two non-vascular plant species, a hornwort Anthoceros agrestis and a liverwort Blasia pusilla, forming plant-cyanobacteria endophytic symbioses. We observe a deep conservation of the systemic starvation response across land plants. However, very few if any components of the starvation network appear to be specific to cyanobacteria hosting plants, providing little evidence for extensive and specific priming to the cyanobiont. Moreover, we found that some bioactive molecules known to be important in initiating the plant-mycorrhiza and nodule-forming bacteria symbioses, may also have a similar role in plant-cyanobacteria symbioses.

植物-微生物互利共生相互作用通常被认为是在营养受限条件下，由宿主植物与微生物间的松散结合演化而来。因此，介导紧密型植物-微生物互利共生的分子网络，或许源自所有陆生植物共有的营养饥饿响应。尽管营养状态与共生相互作用之间的分子关联已得到充分阐明，但在部分共生体系中其机制仍有待解析，这在植物与蓝细菌（Cyanobacteria）的共生关联中尤为突出。
为验证饥饿响应网络在陆生植物中的保守性，并探究植物-蓝细菌共生体系中营养饥饿与共生启动之间的关联，本研究对两种可形成植物-蓝细菌内生共生（endophytic symbiosis）的无维管植物（non-vascular plant）物种的营养饥饿转录响应展开分析，这两种植物分别为角苔（hornwort）*Anthoceros agrestis* 与地钱（liverwort）*Blasia pusilla*。研究发现，系统性饥饿响应在陆生植物中具有高度保守性。然而，饥饿响应网络中几乎不存在（即便存在也极少）专属于共生蓝细菌宿主植物的组分，几乎无法为蓝细菌共生体（cyanobiont）存在广泛且特异性预激活的现象提供证据。此外，本研究发现，一些已知在启动植物-菌根（mycorrhiza）以及结瘤细菌共生过程中发挥关键作用的生物活性分子，或许在植物-蓝细菌共生体系中也具备类似功能。