An integrated approach to highlight biological responses of Pisum sativum root to nano-TiO2 exposure in a biosolid-amended agricultural soil

Abstract

This study focused on crop plant response to a simultaneous exposure to biosolid and TiO at micro-and nano-scale, being biosolid one of the major sink of TiO 2 nanoparticles released into the soil environment. We settled an experimental design as much as possible realistic, at microcosm scale, using the crop Pisum sativum. This experimental design supported the hypotheses that the presence of biosolid in the farming soil might influence plant growth and metabolism and that, after TiO 2 spiking, the different dimension and crystal forms of TiO 2 might be otherwise bioavailable and differently interacting with the plant system. To test these hypotheses, we have considered different aspects of the response elicited by TiO 2 and biosolid at cellular and organism level, focusing on the root system, with an integrative approach. In our experimental conditions, the presence of biosolid disturbed plant growth of P. sativum, causing cellular damages at root level, probably through mechanisms not only oxidative stress-dependent but also involving altered signalling processes. These disturbances could depend on non-humified compounds and/or on the presence of toxic elements and of nanoparticles in the biosolid-amended soil. The addition of TiO 2 particles in the sludgeamended soil, further altered plant growth and induced oxidative and ultrastructural damages. Although non typical dose-effect response was detected, the most responsiveness treatments were found for the anatase crystal form, alone or mixed with rutile. Based on ultrastructural observations, we could hypothesise that the toxicity level of TiO 2 nanoparticles may depend on the cell ability to isolate nanoparticles in subcellular compartments, avoiding their interaction with organelles and/or metabolic processes. The results of the present work suggest reflections on the promising practice of soil amendments and on the use of nanomaterials and their safety for food plants and living organisms.

Synchrotron Radiation Spectroscopy and Transmission Electron Microscopy Techniques to Evaluate TiO2 NPs Incorporation, Speciation, and Impact on Root Cells Ultrastructure of Pisum sativum L. Plants

“…In tomato fruits, soil amended with sewage sludge containing TiO 2 NPs increased growth and yield with few changes in the elemental composition and non-altered the biochemical responses [ 17 ]. On the other hand, some negative effects were recently reported: in Pisum sativum and Lens culinaris , oxidative stress [ 18 , 19 ] and imbalance in the mineral nutrition [ 20 ]; in wheat crop, altered metabolism [ 21 ], in barley, delay in reaching the physiological maturity [ 22 ]; in Allium sativum , Lens culinaris and Vicia faba , phyto- and genotoxicity [ 3 , 19 , 23 ]. Toxicity and benefits of TiO 2 NPs are thus not only associated with size, but also with concentration [ 24 ], and plant species [ 25 ] in addition to the properties of receiving soils, which may influence the in-situ TiO 2 processes and induce changes in NPs’ bioavailability and bioactivity [ 26 , 27 , 28 ].…”

“…Previous studies showed that the complex system Bs-soil-plant was impacted by the presence of TiO 2 NPs, inducing negative threats to the quality of both soil and P. sativum plants [ 18 , 20 ]. In these studies, the experimental design was conceived to represent real scenarios of best- and worst-case load of NPs (80 and 800 mg TiO 2 per Kg of soil) through Bs-amended farm soils [ 18 , 20 ].…”

“…Previous studies showed that the complex system Bs-soil-plant was impacted by the presence of TiO 2 NPs, inducing negative threats to the quality of both soil and P. sativum plants [ 18 , 20 ]. In these studies, the experimental design was conceived to represent real scenarios of best- and worst-case load of NPs (80 and 800 mg TiO 2 per Kg of soil) through Bs-amended farm soils [ 18 , 20 ]. Modifications in the plant growth, oxidative stress in terms of lipid peroxidation and production of hydrogen peroxide, as well as the reduced bioavailability of some soil mineral nutrients, stress on the soil microbial population and imbalance in the plant mineral nutrition were recorded [ 18 , 20 ].…”

“…In these studies, the experimental design was conceived to represent real scenarios of best- and worst-case load of NPs (80 and 800 mg TiO 2 per Kg of soil) through Bs-amended farm soils [ 18 , 20 ]. Modifications in the plant growth, oxidative stress in terms of lipid peroxidation and production of hydrogen peroxide, as well as the reduced bioavailability of some soil mineral nutrients, stress on the soil microbial population and imbalance in the plant mineral nutrition were recorded [ 18 , 20 ]. Although the non-typical dose-effect relationship were observed in these studies, the worst plant response to anatase or mix of anatase and rutile was evidenced [ 18 , 20 ].…”

High performance of chitosan-co-polyacrylamide-TiO₂ crosslinked glutaraldehyde hydrogel as soil conditioner for soybean plant (Glycine max)

“…TiO 2 compounds are also able to increase photosynthetic efficiency in plants (Khater, 2015;Giorgetti et al, 2019). With the advantages possessed by chitosan and TiO 2 in enhancing plant growth, in this study the binding of chitosan-TiO 2 was carried out to become a chitosan-TiO2 composite material.…”