Fungi-derived agriculturally important nanoparticles and their application in crop stress management - Prospects and environmental risks.

Nanotechnology has a wide range of agricultural applications, with emphasize on the development of novel nano-agrochemicals such as, nano-fertilizer and nano-pesticides. It has a significant impact on sustainable agriculture by increasing agricultural productivity, while reducing the use of inorganic fertilizers, pesticides, and herbicides. Nano-coating delivery methods for agrochemicals have improved agrochemical effectiveness, safety, and consistency. Biosynthesis of nanoparticles (NPs) has recently been recognized as an effective tool, contrary to chemically derived NPs, for plant abiotic and biotic stress control, and crop improvement. In this regard, fungi have tremendous scope and importance for producing biogenic NPs of various sizes, shapes, and characteristics. Fungi are potential candidates for synthesis of biogenic NPs due to their enhanced bioavailability, biological activity, and higher metal tolerance. However, their biomimetic properties and high capacity for dispersion in soil, water environments, and foods may have negative environmental consequences. Furthermore, their bioaccumulation raises significant concerns about the novel properties of nanomaterials potentially causing adverse biological effects, including toxicity. This review provides a concise outline of the growing role of fungal-mediated metal NPs synthesis, its potential applications in crop field, and associated issues of nano-pollution in soil and its future implications.

Na+ and Cl- induce differential physiological, biochemical responses and metabolite modulations in vitro in contrasting salt-tolerant soybean genotypes.

Chloride and sodium constitute as the major ions in most saline soils, contributing to salt-induced damage in plants. Research on salt tolerance has mostly concentrated on the sodium toxicity; however, chloride toxicity also needs to be considered to understand the physiological, biochemical, and metabolite changes under individual and additive salts. In this study, we investigated the effect of individual Na+ and/or Cl- ions (equimolar 100 mM NaCl, Na+ and Cl- salts) using in vitro cultures of four soybean genotypes with contrasting salt tolerance. In general, all the treatments significantly induced antioxidant enzymes activities such as catalase, ascorbate peroxidase, glutathione reductase, guaiacol peroxidase, and superoxide dismutase and osmolytes including proline, glycine betaine, and total soluble sugar (TSS). Both individual (Na+, Cl-) and additive (NaCl) stresses induced more pronounced activation of antioxidant enzyme machinery and osmolytes accumulation in the tolerant genotypes (MAUS-47 and Bragg). The sensitive genotypes (Gujosoya-2 and SL-295) showed higher accumulation of Na+ and Cl-, while the tolerant genotypes were found to maintain a low Na+/K+ and high Ca2+ level in combination with enhanced antioxidant defense and osmotic adjustment. Gas chromatography-mass spectrometry (GC-MS)-based metabolomic profiling depicted the association of certain metabolites under individualistic and additive salt effects. The genotype-specific metabolic changes indicated probable involvement of azetidine, 2-furanmethanol, 1,4-dioxin, 3-fluorothiophene, decanoic acid and 2-propenoic acid methyl ester in salt-tolerance mechanism of soybean.