Calabrese Silvia, Cusant Loic, Sarazin Alexis, Niehl Annette, Erban Alexander, Brulé Daphnée, Recorbet Ghislaine, Wipf Daniel, Roux Christophe, Kopka Joachim, Boller Thomas, Courty Pierre-Emmanuel
Department of Environmental Sciences, Botany, Zurich-Basel Plant Science Center, University of Basel, Basel, Switzerland.
Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UPS, CNRS, Castanet-Tolosan, France.
Front Plant Sci. 2019 Dec 12;10:1617. doi: 10.3389/fpls.2019.01617. eCollection 2019.
In arbuscular mycorrhizal (AM) symbiosis, key components of nutrient uptake and exchange are specialized transporters that facilitate nutrient transport across membranes. As phosphate is a nutrient and a regulator of nutrient exchanges, we investigated the effect of P availability to extraradical mycelium (ERM) on both plant and fungus transcriptomes and metabolomes in a symbiocosm system. By perturbing nutrient exchanges under the control of P, our objectives were to identify new fungal genes involved in nutrient transports, and to characterize in which extent the fungus differentially modulates its metabolism when interacting with two different plant species. We performed transportome analysis on the ERM and intraradical mycelium of the AM fungus associated to and under high and low P availability in ERM, using quantitative RT-PCR and Illumina mRNA-sequencing. We observed that mycorrhizal symbiosis induces expression of specific phosphate and ammonium transporters in both plants. Furthermore, we identified new AM-inducible transporters and showed that a subset of phosphate transporters is regulated independently of symbiotic nutrient exchange. mRNA-Sequencing revealed that the fungal transportome was not similarly regulated in the two host plant species according to P availability. Mirroring this effect, many plant carbohydrate transporters were down-regulated in mycorrhizal root tissue. Metabolome analysis revealed further that AM root colonization led to a modification of root primary metabolism under low and high P availability and to a decrease of primary metabolite pools in general. Moreover, the down regulation of the sucrose transporters suggests that the plant limits carbohydrate long distance transport (i.e. from shoot to the mycorrhizal roots). By simultaneous uptake/reuptake of nutrients from the apoplast at the biotrophic interface, plant and fungus are both able to control reciprocal nutrient fluxes.
在丛枝菌根（AM）共生中，养分吸收和交换的关键成分是促进养分跨膜运输的特殊转运蛋白。由于磷既是一种养分，也是养分交换的调节因子，我们在共生系统中研究了根外菌丝体（ERM）的磷有效性对植物和真菌转录组及代谢组的影响。通过在磷的控制下干扰养分交换，我们的目标是鉴定参与养分运输的新真菌基因，并表征真菌在与两种不同植物物种相互作用时对其代谢的差异调节程度。我们使用定量RT-PCR和Illumina mRNA测序，对ERM中磷有效性高和低时与 和 相关的AM真菌的ERM和根内菌丝体进行了转运组分析。我们观察到菌根共生诱导了两种植物中特定磷和铵转运蛋白的表达。此外，我们鉴定了新的AM诱导型转运蛋白，并表明一部分磷转运蛋白的调节独立于共生养分交换。mRNA测序显示，根据磷的有效性，真菌转运组在两种宿主植物物种中的调节方式不同。反映这种效应的是，许多植物碳水化合物转运蛋白在 菌根根组织中下调。代谢组分析进一步表明，AM根定殖在磷有效性高和低时都会导致根初级代谢的改变，总体上导致初级代谢产物库的减少。此外，蔗糖转运蛋白的下调表明植物限制了碳水化合物的长距离运输（即从地上部分到菌根根）。通过在生物营养界面同时从质外体吸收/再吸收养分，植物和真菌都能够控制相互的养分通量。
