Low Doses of Anatase and Rutile Nanoparticles Differently Modulate Photosynthesis and Regulatory Genes: A Contribution to the Nanoagroindustry

Nuno Mariz-Ponte,Isabel Amorim,Conceição Santos,Sara Sario,Rafael Mendes,Cristiana Correia,Maria Dias,Anicia Gomes,Paulo Oliveira-Pinto,Marino Santos,José Ferreira De Oliveira,Márcio Couto,Emil Gimranov

doi:10.3390/agriculture12020190

Nuno Mariz-Ponte, Isabel Amorim + Show 11 more

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https://doi.org/10.3390/agriculture12020190

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Abstract

Industrial applications of titanium dioxide nanoparticles (TiO2 NPs) are wide, and their use in nano-fertilizing technology has been proposed in the last few years. Bioactivity evaluation of different TiO2 NPs formulations is therefore crucial, not only to select the most appropriate formulation but also to validate potential agro-applications. In the current work, we compared the bioactivity of the two most used TiO2 NPs formulations (anatase and rutile–anatase) on the photosynthesis of Lactuca sativa. Seeds were exposed to concentrations of 0, 10, and 50 mg L−1 of anatase (A) or rutile–anatase (RA). Germination rate was not affected by NPs, but root growth was stimulated mainly by RA50. Compared with control, RA showed positive effects on photophosphorylation-related parameters. A50 was more efficient in promoting the gas exchange phase (PN, Ci, gs, and E) and in stimulating the absorption of some nutrients. Expanding on the biochemical and physiological data, we show that RA50 stimulated several genes coding for proteins involved in the electron transport in thylakoids (psbA, petB, petA, psaA, psaC, ndhA, ndhD) and ATP synthesis (atpA, atpB). The transcript coding for the large subunit of RuBisCO (rbcL), was stimulated by lower concentration (RA10). This suggests that RuBisCO is highly sensitive to these NPs even at low doses. RA at low doses has been demonstrated to be the most promising NP. These discriminative effects of TiO2 NPs, based on their formulation and dose, may present advantages for their use in the precision nanoagroindustry.

Highlights

This article is an open access articleNanoagriculture is opening a new era in the agro-food industry by playing an emergent role in improving crop production, providing highly efficient and sustainable nanopesticides, nanofertilizers, and nanosensors [1,2,3,4,5,6]
RA conditions showed a hormetic profile, with roots exposed to RA50 being two times longer than those exposed to RA10 (p < 0.05) (Table 2)
In line with the data of Wang et al [45], we suggest that the low doses used here of A either do not influence chlorophylls biosynthesis or slightly increase their biosynthetic pathways, while stimulating important defense pathways

Summary

Introduction

This article is an open access articleNanoagriculture is opening a new era in the agro-food industry by playing an emergent role in improving crop production, providing highly efficient and sustainable nanopesticides, nanofertilizers, and nanosensors [1,2,3,4,5,6]. It has been shown that these TiO2 NPs can reduce the phytotoxicity of other metal contaminants such as Al and Pb in lettuce plants [10]. TiO2 NPs occur as anatase, rutile, or brookite. Anatase and rutile (R) differ in structure: A is constituted by a tetragonal form with four TiO2 units, while the tetragonal form of the R is constituted by two TiO2 units. In addition to these different structures, the optical, mechanical, and chemical proprieties are significantly different, namely color and photocatalytic activity, which promote distinct application in the industry [12,13]. Previous studies have shown that A is less genotoxic than RA, and positively influences lettuce and basil seedlings’

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