Iron oxide nanoparticles and selenium supplementation improve growth and photosynthesis by modulating antioxidant system and gene expression of chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR) in arsenic-stressed Cucumis melo.

Current research reveals the positive role of iron oxide nanoparticles (IONPs) and selenium (Se) in extenuation of arsenic (As) induced toxicity in Cucumis melo. C. melo plants grown in As spiked soil (20 mg kg-1 As) showed reduced growth, chlorophyll (Chl) content, photosynthetic rate, stomatal conductivity and transpiration. On the other hand, the alone applications of IONPs or Se improved growth and physiochemical parameters of C. melo plants. Additionally, exogenous application IONPs and Se synergistically improved the activity of antioxidative enzymes and glyoxalase system in C. melo plants. In addition, the collective treatment of IONPs and Se reduced As uptake, enhanced rate of photosynthesis and increased gas exchange attributes of C. melo plants under As stress. Interactive effect of IONPs and Se regulated reduced glutathione (GSH), oxidized glutathione (GSSG) and ascorbate (AsA) content in C. melo plants exposed to As-contaminated Soil. IONPs and Se treatment also regulated expression of respiratory burst oxidase homologue D (RBOHD) gene, chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR). Therefore, the combined treatment of IONPs and Se may enhance the growth of crop plants by alleviating As stress.

Ameliorative effect of co-application of Bradyrhizobium japonicum EI09 and Se to mitigate chromium stress in Capsicum annum L.

The present study was conducted to explore the potential of Bradyrhizobium japonicum EI09 (EI09) and selenium (Se) alone or in combination to mitigate hexavalent chromium (Cr6+) stress in Capsicum annum L. Chromium stressed plants exhibited significant reduction in biomass, chlorophyll content and gas exchange characteristics. The inoculated seedlings subjected to Cr6+stress showed improvement in growth, proline content, gas exchange attributes and total soluble proteins. Likewise, inoculated C. annum seedlings exhibited augmented activity of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) under Cr6+ stress. The Cr6+ stress mitigation in inoculated seedlings was ascribed to reduction in malondialdehyde (MDA) content, hydrogen peroxide (H2O2) besides increase activity of flavonoids, proline, phenolic content along with modulation of antioxidative enzymes. The growth-enhancing attributes of bacteria such as indole acetic acid (IAA) content and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity enhanced growth in Cr6+-stressed plants. Moreover, co-treatment of EI09 and 5 µM Se effectively mitigated Cr (VI) stress in C. annum plants. Current studies provide a novel insight into potential of B. japonicum EI09 and Se in reduction of Cr6+ toxicity in C. annum plants.

Chemical constituents of Cordia latifolia and their nematicidal activity.

Following nematicidal activity-guided isolation studies on the fruits, bark, and leaves of Cordia latifolia, two new constituents, cordinoic acid (=11-oxours-12-ene-23,28-dioic acid; 1) and cordicilin (=2-{[(E)-3-(3,4-dihydroxyphenyl)prop-2-enoyl]oxy}-3-[4-hydroxy-3-(stearoyloxy)phenyl]propanoic acid; 2) were isolated from the stem and leaves, respectively, together with nine known compounds, namely cordioic and cordifolic acid from the stem bark, latifolicin A-D and rosmarinic acid from the fruits, and cordinol and cordicinol from the leaves. Their structures were determined by means of spectroscopic analyses including 1D- and 2D-NMR techniques. The nematicidal activities of these constituents were determined against the root-knot nematode Meloidogyne incognita. Hundred percent mortality was caused by all of these after 72 h at a 0.125% concentration. Compound 1 and cordioic acid were most active and caused 100% mortality after 24 h at a 0.50% concentration. Furthermore, compound 2, the ester of rosemarinic acid, was found to be more active than the free acid.