Effects of silicon nanoparticles on molecular, chemical, structural and ultrastructural characteristics of oat (Avena sativa L.)

Nowadays, nanoparticles are extensively being utilized in medicine, industry, and agriculture thus distributed into the environment. Hence, it is essential to examine exactly the impact of these materials on a variety of organisms, including various species of plants. Therefore, in the current study, we compared the effects of sodium silicate and nano silicon (SiNP) (both at two concentrations of 5 and 10 mM) separately on lignification of the xylem cell wall, antioxidant enzyme activities, ultrastructure of leaf and root cells, expression of silicon transporter (Lsi1) and phenylalanine ammonia lyase (PAL), and also evaluated the protein content and chemical content of oat plants (Avena saliva L.) cultured hydroponically. The results indicated that SiNPs didn't have a toxic effect on the oat plants, and in many cases they enhanced plant growth. The effect of SiNPs on the chemical content of the treated plants was almost identical with silicate. The silicon transporter (Lsi1) gene was expressed in plants exposed to SiNPs, however, at lower levels (similar to 37% in roots) than those exposed to silicate treatments. The SiNPs increased PAL expression and lignification in leaves and roots, however, at lower levels those of silicate ('50% in fourth leaves of 10 mM concentration). They were aggregated in the roots (268-366 nm) and deposited in nano size on the cell walls of leaves. In general, their effects in the plants were identical to silicate but differed in intensity.