Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.
Mycorrhiza. 2021 Jan;31(1):69-83. doi: 10.1007/s00572-020-01001-6. Epub 2020 Nov 16.
Many plant species form symbioses with ectomycorrhizal fungi, which help them forage for limiting nutrients in the soil such as inorganic phosphate (Pi). The transcriptional responses to symbiosis and nutrient-limiting conditions in ectomycorrhizal fungal hyphae, however, are largely unknown. An artificial system was developed to study ectomycorrhizal basidiomycete Paxillus involutus growth in symbiosis with its host tree Pinus sylvestris at different Pi concentrations. RNA-seq analysis was performed on P. involutus hyphae growing under Pi-limiting conditions, either in symbiosis or alone. We show that Pi starvation and ectomycorrhizal symbiosis have an independent effect on the P. involutus transcriptome. Notably, low Pi availability induces expression of newly identified putative high-affinity Pi transporter genes, while reducing the expression of putative organic acid transporters. Additionally, low Pi availability induces a close transcriptional interplay between P and N metabolism. GTP-related signalling was found to have a positive effect in the maintenance of ectomycorrhizal symbiosis, whereas multiple putative cytochrome P450 genes were found to be downregulated, unlike arbuscular mycorrhizal fungi. We provide the first evidence of global transcriptional changes induced by low Pi availability and ectomycorrhizal symbiosis in the hyphae of P. involutus, revealing both similarities and differences with better-characterized arbuscular mycorrhizal fungi.
许多植物物种与外生菌根真菌形成共生关系，外生菌根真菌帮助它们在土壤中寻找限制营养物质，如无机磷（Pi）。然而，外生菌根真菌菌丝体共生和营养限制条件下的转录反应在很大程度上尚不清楚。开发了一种人工系统来研究外生菌根担子菌 Paxillus involutus 与宿主树 Pinus sylvestris 在不同 Pi 浓度下的共生生长。在 Pi 限制条件下，无论是在共生状态还是单独生长，对 P. involutus 菌丝体进行了 RNA-seq 分析。我们表明，Pi 饥饿和外生菌根共生对 P. involutus 转录组有独立的影响。值得注意的是，低 Pi 可用性诱导新鉴定的假定高亲和力 Pi 转运体基因的表达，同时减少假定有机酸转运体的表达。此外，低 Pi 可用性诱导 P 和 N 代谢之间的紧密转录相互作用。发现 GTP 相关信号转导对维持外生菌根共生具有积极影响，而与丛枝菌根真菌不同的是，多个假定的细胞色素 P450 基因被下调。我们提供了低 Pi 可用性和外生菌根共生在外生菌根真菌菌丝体中诱导的全球转录变化的第一个证据，揭示了与更好表征的丛枝菌根真菌的相似性和差异。
