Engineered Gold Nanoparticles and Plant Adaptation Potential

Abstract

Use of metal nanoparticles in biological system has recently been recognised although little is known about their possible effects on plant growth and development. Nanoparticles accumulation, translocation, growth response and stress modulation in plant system is not well understood. Plants exposed to gold and gold nanoparticles have been demonstrated to exhibit both positive and negative effects. Their growth and yield vary from species to species. Cytoxicity of engineered gold nanoparticles depends on the concentration, particle size and shape. They exhibit increase in vegetative growth and yield of fruit/seed at lower concentration and decrease them at higher concentration. Studies have shown that the gold nanoparticles exposure has improved free radical scavenging potential and antioxidant enzymatic activities and alter micro RNAs expression that regulate different morphological, physiological and metabolic processes in plants. These modulations lead to improved plant growth and yields. Prior to the use of gold nanoparticles, it has been suggested that its cost may be calculated to see if it is economically feasible.

Keywords: Gold; Growth response; Plant mechanism; Productivity; Stress modulation; Uptake.

Fig. 1

Interaction of gold nanoparticles with plant/soil system and possible entrance in food chain

Fig. 2

Gold nanoparticles in Brassica juncea. a Leaf. b Stem. c Root. d Leaf cell wall [50]

Fig. 3

Images of barley (Hordeum vulgare) primary root tips. Light microscopic observation (magnification, ten times) of longitudinal sections of barley primary root tips of (a) control plants and (b) plants exposed to 10 μg mL⁻¹ gold nanoparticles; TEM images of root cross-sections of (c) control plants and (d) plants exposed to 10 μg mL⁻¹ gold nanoparticles. Bacteria (asterisk) and gold nanoparticles (arrows). OM outer matrix, IM inner matrix, TW thick wall [24]

Fig. 4

Concentration-dependent effects of gold nanoparticle exposure on Hordeum vulgare after 2 weeks of exposure. a Photos of barley seedlings, b fresh biomass of leaves (empty symbols) and roots (filled symbols) of barley plants (mean ± one standard deviation for three individual batches with four to ten barley seedlings each), c leaf lengths, and d root lengths of barley plants (box plots represent median values including 14–21 individual data sets per concentration; bars give minimum and maximum values excluding outliers marked as red crosses) [24]