Metabolic Profiling and Metabolite Correlation Network Analysis Reveal That Fusarium solani Induces Differential Metabolic Responses in Lotus japonicus and Lotus tenuis against Severe Phosphate Starvation.

Oscar Adolfo Ruiz,Alexander Erban,Amira Susana Nieva,Pedro Carrasco,Joachim Kopka,Fernando Matías Romero

doi:10.3390/jof7090765

Abstract

Root fungal endophytes are essential mediators of plant nutrition under mild stress conditions. However, variations in the rhizosphere environment, such as nutrient depletion, could result in a stressful situation for both partners, shifting mutualistic to nonconvenient interactions. Mycorrhizal fungi and dark septate endophytes (DSEs) have demonstrated their ability to facilitate phosphate (Pi) acquisition. However, few studies have investigated other plant–fungal interactions that take place in the root environment with regard to phosphate nutrition. In the present research work, we aimed to analyze the effect of extreme Pi starvation and the fungal endophyte Fusarium solani on the model Lotus japonicus and the crop L. tenuis. We conducted metabolomics analysis based on gas chromatography-mass spectrometry (GC-MS) on plant tissues under optimal conditions, severe Pi starvation and F.solani presence. By combining statistical and correlation network analysis strategies, we demonstrated the differential outcomes of the two plant species against the combination of treatments. The combination of nutritional stress and Fusarium presence activated significant modifications in the metabolism of L. japonicus affecting the levels of sugars, polyols and some amino acids. Our results display potential markers for further inspection of the factors related to plant nutrition and plant–fungal interactions.

Highlights

Lotus spp. belong to the Fabaceae family, which contains approximately 130 species.Lotus legumes have the ability to tolerate different biotic and abiotic stresses, and some of them are forage crops in constrained areas that have limitations for traditional agriculture use due to the restrictive soil conditions [1]
In agreement with the effect on biomass, Pi starvation affected the primary metabolism as a dominant experimental factor, with only minor contributions of
Guided by the previous analyses, we focused on the combinatorial FUS+P- stress of the L. japonicus (Supplementary Figure S2A) shoot samples compared to the L. tenuis shoot samples (Supplementary Figure S2B)

Summary

Introduction

Lotus spp. belong to the Fabaceae family, which contains approximately 130 species.Lotus legumes have the ability to tolerate different biotic and abiotic stresses, and some of them are forage crops in constrained areas that have limitations for traditional agriculture use due to the restrictive soil conditions [1]. Lotus tenuis is a legume used as a forage resource in the Flooding Pampa region (Buenos Aires, Argentina). This region is mainly characterized by flooding, high salinity and high pH values, which lead to the low availability of nutrients such as phosphorus and iron in the soil. Research performed on L. tenuis has been accompanied by research on the model L. japonicus [4]. Both species have been used to characterize the response of legumes to biotic and abiotic stresses. Abiotic stress responses have been extensively studied, including that on a larger panel of Lotus species [5,6,7,8,9,10,11]

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