Polymer-Modified Single-Walled Carbon Nanotubes Affect Photosystem II Photochemistry, Intersystem Electron Transport Carriers and Photosystem I End Acceptors in Pea Plants.

Nia Petrova,Petar Petrov,Sashka Krumova,Momchil Paunov,Vasilij Goltsev,Violeta Velikova

doi:10.3390/molecules26195958

Abstract

Single-walled carbon nanotubes (SWCNT) have recently been attracting the attention of plant biologists as a prospective tool for modulation of photosynthesis in higher plants. However, the exact mode of action of SWCNT on the photosynthetic electron transport chain remains unknown. In this work, we examined the effect of foliar application of polymer-grafted SWCNT on the donor side of photosystem II, the intersystem electron transfer chain and the acceptor side of photosystem I. Analysis of the induction curves of chlorophyll fluorescence via JIP test and construction of differential curves revealed that SWCNT concentrations up to 100 mg/L did not affect the photosynthetic electron transport chain. SWCNT concentration of 300 mg/L had no effect on the photosystem II donor side but provoked inactivation of photosystem II reaction centres and slowed down the reduction of the plastoquinone pool and the photosystem I end acceptors. Changes in the modulated reflection at 820 nm, too, indicated slower re-reduction of photosystem I reaction centres in SWCNT-treated leaves. We conclude that SWCNT are likely to be able to divert electrons from the photosynthetic electron transport chain at the level of photosystem I end acceptors and plastoquinone pool in vivo. Further research is needed to unequivocally prove if the observed effects are due to specific interaction between SWCNT and the photosynthetic apparatus.

Highlights

In the recent decade, carbon-based nanomaterials and single-walled carbon nanotubes (SWCNT) in particular have been involved in the development of state-of-the-art approaches in agronomy and plant biotechnology
Besides partial inactivation of photosystem II (PSII) reaction centres, SWCNT interfere with the photosynthetic electron transport chain at the level of intersystem electron carriers and the photosystem I (PSI)
The complementary pieces of information obtained through analyses of both Chl fluorescence induction curves and the modulated reflection at 820 nm allowed for comprehensive examination of the operation of the donor side of PSII, the acceptor side of PSI and the intersystem electron transport in pea plants treated with different concentrations of polymer-modified SWCNT and polymer only

Summary

Introduction

Carbon-based nanomaterials and single-walled carbon nanotubes (SWCNT) in particular have been involved in the development of state-of-the-art approaches in agronomy and plant biotechnology. Chitosan-complexed SWCNT were demonstrated to serve as a DNA carrier in a novel technique for genetic transformation of the chloroplast genome in a number of plant species [2]. The spectroscopic and electronic properties of SWCNT [3] intuitively make them highly appropriate candidate to be utilized in development of novel techniques for augmentation of photosynthesis and modulation of stress responses in photosynthetic organisms. Many of the predicted applications of SWCNT in plant biotechnologies require knowledge of their modes of action on the photosynthetic machinery. SWCNT were assumed to endow chloroplasts with wider photosynthetic action spectrum due to their absorbance in the ultraviolet, visible and near-infrared regions [4]

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