Arbuscular mycorrhizal symbiosis enhances tomato lateral root formation by modulating CEP2 peptide expression

第一作者：Yu-Heng Hsieh

第一单位：台湾大学

通讯作者：Shu-Yi Yang

 Abstarct 

背景+问题：Plant lateral root (LR) growth is usually stimulated by arbuscular mycorrhizal (AM) symbiosis. However, the molecular mechanism is still unclear. 

植物侧根生长通常会受到丛枝菌根共生的刺激。但是，其背后的分子机制还不清楚。

主要研究：We used gene expression analysis, peptide treatment and virus-induced gene alteration assays to demonstrate that C-terminally encoded peptide (CEP2) expression in tomato was downregulated during AM symbiosis to mitigate its negative effect on LR formation through an auxin-related pathway. 

本文中，作者利用基因表达分析、多肽处理和病毒介导的基因沉默实验，发现番茄中CEP2的表达在丛枝菌根共生过程中被下调，从而通过一个与生长素相关的途径降低其对于番茄侧根形成的负面影响。

结果1-菌根共生表型：We showed that enhanced LR density and downregulated CEP2 expression were observed during mycorrhizal symbiosis. 

作者在丛枝菌根共生过程中，发现番茄的侧根密度增加，同时CEP2的表达下降。

结果2-外施CEP2：Synthetic CEP2 peptide treatment reduced LR density and impaired the expression of genes involved in indole-3-butyric acid (IBA, the precursor of indole-3-acetic acid (IAA)) to IAA conversion, auxin polar transport and the LR-related signaling pathway; however, application of IBA or synthetic auxin NAA to the roots may rescue both defective LR formation and reduced gene expression. 

通过人工合成的CEP2多肽处理，降低了侧根密度，并且参与IBA-IAA转变、生长素极性运输以及侧根相关信号转导的基因表达受到紊乱；但是，通过IBA或者人工合成的NAA处理根，能够拯救侧根形成缺陷和基因表达降低等表型。

结果3-CEP2受体：CEP receptor 1 (CEPR1) might be the receptor of CEP2 since its knockdown plants did not respond to CEP2 treatment. 

CEPR1可能是CEP2的受体，该基因的敲低会导致植株不响应CEP2的处理。

结果4-CEP2过表达和敲低：Most importantly, the LR density of CEP2 overexpression or knockdown plants could not be further increased by AM inoculation, suggesting that CEP2 was critical for AM-induced LR formation. 

此外，接种丛枝菌根接种并不会进一步增加CEP2过表达或者敲低植株的侧根密度，说明CEP2对于丛枝菌根诱导的侧根形成至关重要。

结论：These results indicated that AM symbiosis may regulate root development by modulating CEP2, which affects the auxin-related pathway.

本文的研究结果揭示了丛枝菌根共生可能通过调节CEP2，影响生长素相关的通路，最终作用于根系发育的调控。

** 楊淑怡 **

doi: https://doi.org/10.1111/nph.18128

Journal: New Phytologist

Published date:  March 31, 2022