Formenti Ludovico, Iwanycki Ahlstrand Natalie, Hassemer Gustavo, Glauser Gaëtan, van den Hoogen Johan, Rønsted Nina, van der Heijden Marcel, Crowther Thomas W, Rasmann Sergio
Laboratory of Functional Ecology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland.
Institute of Ecology and Evolution, Terrestrial ecology, University of Bern, Bern, Switzerland.
iScience. 2023 Apr 10;26(5):106632. doi: 10.1016/j.isci.2023.106632. eCollection 2023 May 19.
Arbuscular mycorrhizal fungi (AMF) have evolved associations with roots of 60% plant species, but the net benefit for plants vary broadly from mutualism to parasitism. Yet, we lack a general understanding of the evolutionary and ecological forces driving such variation. To this end, we conducted a comparative phylogenetic experiment with 24 species of encompassing worldwide distribution, to address the effect of evolutionary history and environment on plant growth and chemical defenses in response to AMF colonization. We demonstrate that different species within one plant genus vary greatly in their ability to associate with AMF, and that AMF arbuscule colonization intensity decreases monotonically with increasing phylogenetic branch length, but not with concomitant changes in pedological and climatic conditions across species. Moreover, we demonstrate that species with the highest colonization levels are also those that change their defensive chemistry the least. We propose that the costs imposed by high AMF colonization in terms of reduced changes in secondary chemistry might drive the observed macroevolutionary decline in mycorrhization.
丛枝菌根真菌（AMF）已与60%的植物物种根系形成共生关系，但这种共生对植物的净效益在从互利共生到寄生的范围内广泛变化。然而，我们对驱动这种变化的进化和生态力量缺乏全面的了解。为此，我们对涵盖全球分布的24个物种进行了比较系统发育实验，以研究进化历史和环境对植物生长以及植物在丛枝菌根真菌定殖时的化学防御反应的影响。我们证明，同一植物属内的不同物种与丛枝菌根真菌形成共生关系的能力差异很大，并且丛枝菌根真菌的丛枝定殖强度随着系统发育分支长度的增加而单调下降，但不随物种间土壤学和气候条件的相应变化而变化。此外，我们证明定殖水平最高的物种也是防御化学变化最小的物种。我们提出，丛枝菌根真菌高定殖率在次生化学变化减少方面所带来的成本可能推动了观察到的菌根共生在宏观进化上的衰退。
