Mycorrhizal fungi involved in C transfer among pines and Oaks

Although gaining much attention in recent years, it is unclear whether mycorrhizal fungi distribute meaningful amounts of resources among trees in ways that increase the fitness of the receiving trees. Hence, we used shaded and sunlit pairs of inter- and intra-species Pinus halepensis and Quercus calliprinos saplings growing outdoors in forest soil. Carbon transfer was measured using pulse labeling with 13CO2 and the mycorrhizal community of each tree was identified by DNA barcoding. Although we did not observe any growth benefits, shaded recipient oaks received carbon from their sunlit pine neighbors and exhibited higher levels of root Non-Structural Carbohydrates (NSC) compared to their control counterparts, which were not connected belowground. Furthermore, sunlit pines connected to shaded oaks were depleted of their starch pools. Conjointly, our results link specific mycorrhizal species to belowground C transfer and suggest C-driven fitness costs and benefits to the trees.

尽管近年来菌根真菌（mycorrhizal fungi）受到学界广泛关注，但目前仍不清楚其是否会以提升受体树木适合度的方式，在树木间传递足量的有效资源。为此，本研究选取户外森林土壤中培育的、涵盖种间与种内配对形式的遮阴-光照组阿勒颇松（*Pinus halepensis*）和刺叶栎（*Quercus calliprinos*）幼树作为实验材料。通过¹³CO₂脉冲标记法测定树木间的碳转移，并通过DNA条形码（DNA barcoding）鉴定每株树木的菌根群落组成。尽管未观测到显著的生长收益，但与地下未建立连接的对照组相比，作为受体的遮阴刺叶栎从光照侧的相邻阿勒颇松处获取了碳源，且根系非结构碳水化合物（Non-Structural Carbohydrates, NSC）水平显著更高。此外，与遮阴刺叶栎建立连接的光照侧阿勒颇松，其体内淀粉储备出现耗竭。综合来看，本研究结果将特定菌根菌种与地下碳转移建立了关联，并表明碳源介导了树木间适合度的成本与收益变化。