Interplay between Coumarin Accumulation, Iron Deficiency and Plant Resistance to Dickeya spp.

Izabela Perkowska,Anna Ihnatowicz,Dominika Siudem,Joanna Siwinska,Ewa Lojkowska,Marta Potrykus

doi:10.3390/ijms22126449

Izabela Perkowska, Anna Ihnatowicz + Show 4 more

Open Access

https://doi.org/10.3390/ijms22126449

Copy DOI

Abstract

Coumarins belong to a group of secondary metabolites well known for their high biological activities including antibacterial and antifungal properties. Recently, an important role of coumarins in plant resistance to pathogens and their release into the rhizosphere upon pathogen infection was discovered. It is also well documented that coumarins play a crucial role in the Arabidopsis thaliana growth under Fe-limited conditions. However, the mechanisms underlying interplay between plant resistance, accumulation of coumarins and Fe status, remain largely unknown. In this work, we investigated the effect of both mentioned factors on the disease severity using the model system of Arabidopsis/Dickeya spp. molecular interactions. We evaluated the disease symptoms in Arabidopsis plants, wild-type Col-0 and its mutants defective in coumarin accumulation, grown in hydroponic cultures with contrasting Fe regimes and in soil mixes. Under all tested conditions, Arabidopsis plants inoculated with Dickeya solani IFB0099 strain developed more severe disease symptoms compared to lines inoculated with Dickeya dadantii 3937. We also showed that the expression of genes encoding plant stress markers were strongly affected by D. solani IFB0099 infection. Interestingly, the response of plants to D. dadantii 3937 infection was genotype-dependent in Fe-deficient hydroponic solution.

Highlights

The secretion of phenolic compounds from roots into the rhizosphere has long been recognised as a component of the acidification-reduction strategy to acquire iron (Fe), occurring in all plant species except grasses [1]
We evaluated the disease symptoms caused by Dickeya spp. strains in Arabidopsis lines differing in coumarin accumulation that were grown under various growth conditions and Fe availability
We investigated here the possible interactions between plant resistance, coumarin content and Fe status by using the plant pathogenic Dickeya spp. strains and a set of selected

Summary

Introduction

The secretion of phenolic compounds from roots into the rhizosphere has long been recognised as a component of the acidification-reduction strategy to acquire iron (Fe), occurring in all plant species except grasses [1]. It was proven that coumarins are involved in Fe chelation and that secretion of coumarins by Arabidopsis roots is induced under. The biological roles of novel enzymes involved in coumarin biosynthesis, which in parallel maintain Fe homeostasis in plants, were elucidated. A key enzyme for the biosynthesis of Arabidopsis major coumarin called scopoletin and its derivatives is Feruloyl-CoA 60 -Hydroxylase (F60 H1) that belongs to a large enzyme family of the. Our group elucidated the biological role of another member of this family, encoded by a strongly Fe-responsive gene (At3g12900), as a scopoletin 8-hydroxylase (S8H) involved in the last step of fraxetin biosynthesis [7]. Fraxetin is a coumarin derived from the scopoletin pathway, containing two adjacent hydroxyl groups in the ortho-position that can efficiently solubilise Fe from the hydroxide precipitates [3,8]. We proved S8H to be involved in coumarin biosynthesis as part of the Fe acquisition machinery [7]

Methods

Results

Conclusion