Auxin Controls Arabidopsis Adventitious Root Initiation by Regulating Jasmonic Acid Homeostasis

Abstract

Vegetative shoot-based propagation of plants, including mass propagation of elite genotypes, is dependent on the development of shoot-borne roots, which are also called adventitious roots. Multiple endogenous and environmental factors control the complex process of adventitious rooting. In the past few years, we have shown that the auxin response factors ARF6 and ARF8, targets of the microRNA miR167, are positive regulators of adventitious rooting, whereas ARF17, a target of miR160, is a negative regulator. We showed that these genes have overlapping expression profiles during adventitious rooting and that they regulate each other's expression at the transcriptional and posttranscriptional levels by modulating the homeostasis of miR160 and miR167. We demonstrate here that this complex network of transcription factors regulates the expression of three auxininducible Gretchen Hagen3 (GH3) genes, GH3.3, GH3.5, and GH3.6, encoding acyl-acid-amido synthetases. We show that these three GH3 genes are required for fine-tuning adventitious root initiation in the Arabidopsis thaliana hypocotyl, and we demonstrate that they act by modulating jasmonic acid homeostasis. We propose a model in which adventitious rooting is an adaptive developmental response involving crosstalk between the auxin and jasmonate regulatory pathways.

Auxin 2016: a burst of auxin in the warm south of China

“…He notably showed that brassinosteroids and auxin display similar effects in shoots but opposite effects in roots on genes involved in cell elongation, suggesting a crucial balance between these two phytohormones in order to promote root growth (Chaiwanon and Wang, 2015). Crosstalk between auxin and jasmonic acid was presented by Catherine Bellini (Umeå University, Umeå, Sweden/IJPB, Versailles, France) who showed that, during adventitious root development, a specific set of ARFs control GH3 expression, which in turn modulates jasmonic acid activity (Gutierrez et al, 2012). Furthermore, Catherine Bellini suggested a possible regulation of jasmonic acid biosynthesis by auxin.…”

Plant growth promoting potential of endophytic bacteria isolated from cashew leaves

“…The plant hormone production is part of the metabolism of several microorganisms associated to plants and they may be regarded as important agents in the regulation of the plant's growth and development (Oliveira et al, 2003). The auxin synthesized by bacteria affects the root system by increasing the number and size of adventitious roots (Gutierrez et al, 2012). One should take into account the fact that the IAA effect may vary according to their concentrations.…”

Branching Out in Roots: Uncovering Form, Function, and Regulation

“…The expression of ARF6 and ARF8 is controlled by MIR167, while ARF17 expression is regulated by MIR160. ARF6, ARF8, and ARF17 oppositely regulate jasmonic acid homeostasis via regulating jasmonic acid-modifying GRETCHEN HAGEN3 (GH3) enzymes (Gutierrez et al, 2009(Gutierrez et al, , 2012Bellini et al, 2014). Auxin transporters are also important for adventitious root formation, with both influx (LAX3) and efflux (PIN1) carriers required for auxin accumulation in the early stages of adventitious root organogenesis (Della Rovere et al, 2013).…”