Molecular characterization of lipoxygenase genes and their expression analysis against biotic and abiotic stresses in Panax ginseng

Lipoxygenase (LOX) belongs to a family of non-heme-iron-containing fatty acid dioxygenases that are widely distributed in plants and animals. LOX involved in the synthesis of jasmonic acid and six-carbon (C6) volatiles which is necessary for plant growth and responses to a wide range of biotic and abiotic stresses. We have isolated and characterized LOX cDNA clones from Panax ginseng Meyer. From their deduced amino acid sequences, two diverse classes of 9-LOX (LOX1, LOX2, and LOX3) and 13-LOX (LOX4, LOX5) are defined in P. ginseng. A GenBank Blast X search revealed that the deduced amino acid of PgLOXs share a high degree of homology with LOX from other plants and mammals especially in three distinct motifs; motif1 harboring iron binding regions, motif2 and motif3. Chloroplast localization was predicted for PgLOX5. PgLOXs displayed organ-specific expression, highly expressed in aerial parts of the plant such as 3-year old flower, stem and leaf tissues. PgLOXs mRNAs were elevated strongly by bacterial infection. Expression of PgLOXs was differentially induced in ginseng not only by mechanical damage and methyl jasmonate but also after exposure to withholding water. Ginseng 13-LOXs positively respond to wounding that may involve in production of C6 volatiles and jasmonic acid at the wounded sites. However, the higher expression of PgLOX3 by water deficit and 82 % of the nucleotide sequence identity with the EST from severe drought-stressed leaves of Populus (CU229089.1) at +6371 bp downstream of PgLOX3 genomic DNA structure can suggest drought tolerance role for PgLOX3. Ginseng LOX genes have different expression pattern which may suggest different specific function against various environmental stresses

Biological synthesis of gold and silver chloride nanoparticles by Glycyrrhiza uralensis and in vitro applications

The current study highlights the rapid biosynthesis of gold nanoparticles (Gu–AuNps) and silver chloride nanoparticles (Gu–AgClNps) by aqueous root extract of Glycyrrhiza uralensis, a medicinal plant. G. uralensis has been reported for anticancer and hepatoprotective effects. The reduction of chloroauric acid and silver nitrate by the Glycyrrhiza root extract prompted the formation of Gu–AuNps and Gu–AgClNps within 4 and 40 min at 80 °C, respectively. The complete reaction did not require supplemental reducing and stabilizing agents, which demonstrated green synthesis. Field emission transmission electron microscopy (FE-TEM) revealed the spherical shape of Gu–AuNps and Gu–AgClNps. X-ray diffraction (XRD) showed face-centred cubic structure of Gu–AuNps and Gu–AgClNps with average crystallite size 12.25 nm and 8.01 nm, respectively. The biosynthesized Gu–AgClNps served as competent antimicrobial agent against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella enterica. Additionally, Gu–AuNps and Gu–AgClNps were analyzed for their catalytic ability to reduce methylene blue as model test pollutant. Likewise, both nanoparticles possessed free radical scavenging activity against 2,2-diphenyl-1-picrylhydrzyl (DPPH). Moreover, in vitro cytotoxicity in murine macrophage (RAW264.7) and human breast cancer (MCF7) cells were evaluated. Thus, the study proposes a green synthesis of Gu–AuNps and Gu–AgClNps by G. uralensis extract and in vitro biological applications. (Figure presented.)