Background and aims

Arbuscular mycorrhizal fungi (AMF) can affect plant root morphology. However, whether the impact is localized or systemic is still unclear.

Methods

A root-splitting microcosm experiment was conducted to examine AMF effects on the root morphology of their host plants at two soil phosphorus (P) levels (5.7 and 25 mg kg⁻¹). The main treatment (MT) had one root chamber with AMF inoculation and the other without, while the arbuscular mycorrhizal (AC) or non-inoculation control (NC) included the active or sterilized fungal inoculum in both root chambers, respectively.

Results

In the MT, root length and surface area were larger in the AMF infected than non-infected chambers, particularly for the secondary lateral root development. Notably, mycorrhizal promotion was stronger at low than high P level. Transcriptome sequencing revealed that AMF infection upregulated gene expressions particularly in pathways related to starch and sucrose metabolism, phenylpropanoid metabolism, terpenoid biosynthesis, fatty acid synthesis, and hormone metabolism and transport. Moreover, the number of upregulated genes was higher at low than high P level. Redundancy analysis demonstrated that the key differential genes were related to nutrients, phytohormones and root morphological traits.

Conclusion

These findings suggest that AMF can induce a localized effect on root morphology, potentially through the upregulation of nutrient- and hormone-related gene expressions, but the magnitude depends on soil P levels.

中文翻译：

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丛枝菌根真菌通过改变低土壤 P 水平的营养激素和植物激素相关基因表达，局部但不全身地影响根系形态

 背景和目标

丛枝菌根真菌 （AMF） 可影响植物根系形态。然而，目前尚不清楚这种影响是局部的还是系统性的。

 方法

进行了根分裂微观世界实验，以检验 AMF 在两个土壤磷 （P） 水平（5.7 和 25 mg ^kg-1）下对其寄主植物根系形态的影响。主要处理 （MT） 有一个接种 AMF 的根室，另一个没有，而丛枝菌根 （AC） 或非接种对照 （NC） 分别在两个根室中包括活性或灭菌的真菌接种物。

 结果

在 MT 中，AMF 感染腔室的根长和表面积大于未感染腔室，尤其是次生侧根发育。值得注意的是，低 P 水平的菌根促进力强于高 P 水平。转录组测序显示，AMF 感染上调基因表达，特别是在与淀粉和蔗糖代谢、苯丙烷代谢、萜类生物合成、脂肪酸合成以及激素代谢和运输相关的途径中。此外，低 P 水平上调基因的数量高于高 P 水平。冗余分析表明，关键差异基因与养分、植物激素和根系形态性状有关。

 结论

这些发现表明，AMF 可以通过上调营养和激素相关基因表达来诱导对根系形态的局部影响，但大小取决于土壤 P 水平。