# Nanoparticles--Plant Interaction: What We Know, Where We Are?
## 1 Introduction  
Nanotechnology is a field of science that has experienced extremely intense growth in recent years. This is due to the enormous hopes that are placed in the use of nanotechnology in various areas of life. The father of nanotechnology should be considered to be Nobel Prize winner [PERSON], who in his lecture in 1959 pointed out that it is possible to obtain nanomaterials [1]. Currently, nanotechnology is one of the fastest developing scientific and industrial fields. The term nanoparticles (NP) is defined as follows: an insoluble or bioperisstent and intentionally produced material that has one or more external dimensions or an internal structure, on a scale from 1 to 100 nm [2]. NP have always been present in the environment because their natural sources are active volcanoes and the soot that is formed in combustion processes, forest fires or dust storms. However, only the development of nanotechnology has contributed to the significant increase of NP in the environment because they are produced intentionally and/or as a result of technological processes such as welding, metal smelting, soldering, welding, vulcanizing, cutting a plasma, combustion engines, heating and power plants, cooking, grilling or due to the use of office laser devices. Nanomaterials (NMs) are used in many different industrial fields such as electronics, medicine, cosmology, agriculture, the food industry or construction [3, 4]. The burst of the nanotechnology industry has resulted in the accumulation of NM in the environment, but their fate in the environment is not yet fully known and understood [5, 6]. An analysis of the impact of NP on living organisms cannot be compared to, for example, the effect of heavy metals that has been studied because NP are different than the basic material in the atomic structure, and their physico-chemical and biological properties are different [7]. The need to identify threats connected with developing nanotechnology is beyond dispute. In recent years, it is more and more frequently pointed out that besides the advantages in our daily life that NM brings us, they may also cause adverse effects and these are not yet fully explored. The new branch of science, nanotoxicology, dedicated to the analysisof the adverse effects of nanoparticles on ecosystems, is intensively developed in recent years [8; 9]. Analyses concern not only the degree of toxicity of NM on living organisms but also detailed studies of their uptake and movement within the plant body on different levels of organization: organs, tissues and cells. A study of the literature data led to the conclusion that results obtained so far are inconsistent, and thus, do not allow one to make generalizations about the effects of NP on plants growth and development. It is not surprising as in this interaction there are two key \"players\": 1/the NP, which vary not only in composition, morphology but also (among others) in size and surface properties and 2/different plant responses to NP, depending (among others) on the developmental stage, organs that interact with NP or growth conditions. At present, a picture emerges showing the stimulation, inhibition or no effect on growth processes under the influence of NP. Due to the abundance of studies on the effects of NP on plants [10; 11; 12; 13; 14], knowledge of plant-NP interactions has increased significantly in recent years [6; 15]. An excellent summary describing the NP influence on plants has been provided lately [16]. Aspect of uptake and movement of NP within the plant body is poorly understood and available literature data indicate the need to investigate the contribution of symplast and apoplast in this process. Key questions about the impact of NP on plants will not find answers before we get complete knowledge about how NP enter plants (including various organs and tissues) and the mechanisms involved in this process and full description of the \"pathways\" of the NP movement within the plant body.