Guillotin Bruno, Etemadi Mohammad, Audran Corinne, Bouzayen Mondher, Bécard Guillaume, Combier Jean-Philippe
Laboratoire de Recherche en Sciences Végétales, Université de Toulouse, UMR5546, CNRS, UPS, F-31326, Castanet-Tolosan, France.
Génomique et Biotechnologie des Fruits, Université de Toulouse, INRA, INP-ENSA Toulouse, Avenue de l'Agrobiopole BP 32607, F-31326, Castanet-Tolosan, France.
New Phytol. 2017 Feb;213(3):1124-1132. doi: 10.1111/nph.14246. Epub 2016 Oct 17.
Root colonization by arbuscular mycorrhizal (AM) fungi is a complex and finely tuned process. Previous studies have shown that, among other plant hormones, auxin plays a role in this process but the specific involvement of Aux/IAAs, the key regulators of auxin responses, is still unknown. In this study, we addressed the role of the tomato Sl-IAA27 during AM symbiosis by using Sl-IAA27-RNAi and pSL-IAA27::GUS stable tomato lines. The data show that Sl-IAA27 expression is up-regulated by the AM fungus and that silencing of Sl-IAA27 has a negative impact on AM colonization. Sl-IAA27-silencing resulted in down-regulation of three genes involved in strigolactone synthesis, NSP1, D27 and MAX1, and treatment of Sl-IAA27-silenced plants with the strigolactone analog GR24 complemented their mycorrhizal defect phenotype. Overall, the study identified an Aux/IAA gene as a new component of the signaling pathway controlling AM fungal colonization in tomato. This gene is proposed to control strigolactone biosynthesis via the regulation of NSP1.
丛枝菌根（AM）真菌在根部的定殖是一个复杂且精细调控的过程。先前的研究表明，在其他植物激素中，生长素在这个过程中发挥作用，但生长素应答的关键调节因子Aux/IAAs的具体参与情况仍不清楚。在本研究中，我们通过使用Sl-IAA27-RNAi和pSL-IAA27::GUS稳定转基因番茄株系，研究了番茄Sl-IAA27在AM共生过程中的作用。数据表明，AM真菌可上调Sl-IAA27的表达，而沉默Sl-IAA27对AM定殖有负面影响。沉默Sl-IAA27导致参与独脚金内酯合成的三个基因NSP1、D27和MAX1表达下调，用独脚金内酯类似物GR24处理沉默Sl-IAA27的植株可弥补其菌根缺陷表型。总体而言，该研究鉴定出一个Aux/IAA基因是控制番茄中AM真菌定殖的信号通路的新组分。该基因被认为通过调控NSP1来控制独脚金内酯的生物合成。
