Sl‐IAA27 regulates strigolactone biosynthesis and mycorrhization in tomato (var. MicroTom). Issue 3 (17th October 2016) - Guillotin, Bruno
Summary: 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 .