Growth-Promoting Gold Nanoparticles Decrease Stress Responses in Arabidopsis Seedlings.

Eleonora Ferrari,Francesco Barbero,Mirita Franz-Wachtel,Marti Busquets-Fité,Victor Puntes,Heinz-R Köhler,Birgit Kemmerling

doi:10.3390/nano11123161

Abstract

The global economic success of man-made nanoscale materials has led to a higher production rate and diversification of emission sources in the environment. For these reasons, novel nanosafety approaches to assess the environmental impact of engineered nanomaterials are required. While studying the potential toxicity of metal nanoparticles (NPs), we realized that gold nanoparticles (AuNPs) have a growth-promoting rather than a stress-inducing effect. In this study we established stable short- and long-term exposition systems for testing plant responses to NPs. Exposure of plants to moderate concentrations of AuNPs resulted in enhanced growth of the plants with longer primary roots, more and longer lateral roots and increased rosette diameter, and reduced oxidative stress responses elicited by the immune-stimulatory PAMP flg22. Our data did not reveal any detrimental effects of AuNPs on plants but clearly showed positive effects on growth, presumably by their protective influence on oxidative stress responses. Differential transcriptomics and proteomics analyses revealed that oxidative stress responses are downregulated whereas growth-promoting genes/proteins are upregulated. These omics datasets after AuNP exposure can now be exploited to study the underlying molecular mechanisms of AuNP-induced growth-promotion.

Highlights

Engineered nanomaterials (ENMs) are distributed into the environment in drastically increasing amounts, yet knowledge on the resulting effects of ENMs on the environment is limited [1,2]
Piella et al [65], with the only difference being the addition of tannic acid (TA), which can interact with the NP surface, inferring higher colloidal stability
NPs are released into the environment in increasing amounts and their high reactivity may cause problems that are not associated with the respective bulk material

Summary

Introduction

Engineered nanomaterials (ENMs) are distributed into the environment in drastically increasing amounts, yet knowledge on the resulting effects of ENMs on the environment is limited [1,2]. Naturally occurring nanomaterials have always existed, in the last decade the emission rate of anthropogenic nanoparticles (NPs), intentionally or unintentionally released, has been continuously rising [3,4]. For these reasons, novel nanosafety approaches to assess the environmental impact of ENMs are required [5]. The unique optical and electrochemical properties of AuNPs [9], as well as their accessibility for various surface functionalizations [10], have been exploited in many applications ranging from diagnostics and cancer therapy [11] to industrial catalysis [12] and water purification [13].

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