Agronomic biofortification of forage crops with zinc and copper for enhancing nutritive potential: a systematic review

Formulation of Zinc oxide/Gum acacia nanocomposite as a novel slow-release fertilizer for enhancing Zn uptake and growth performance of Spinacia oleracea L

Zinc (Zn) deficiency has caused nutritional disorders in 17% of the world's population; thus, producing Zn-enriched plants as a dietary source is necessary. Recently, nanofertilizers have gained much attention as a substitute for conventional fertilizers; however, soil application of polymer-coated Zn-based nanofertilizer has not been explored much. The present study depicts the green synthesis of ZnO nanoparticles using Melia azedarach L. leaf extract, whose phytoconstituents have reducing abilities. The synthesized nanoparticles were combined with gum acacia (GA) to form a ZnOGA nanocomposite. The structural and morphological properties of ZnOGA were studied using XRD, FTIR, FESEM, and EDX. A pot experiment study was carried out with Spinacia oleracea L. at various doses (3, 5, and 10 mg/kg) of the synthesized ZnOGA to evaluate its effectiveness as a slow-release fertilizer and was compared with a commercial Zn fertilizer. The plant growth studies revealed a significant increase in the phyto-morphological traits of the plants fertilized with ZnOGA compared to commercial fertilizer. The plants also displayed significantly higher contents of protein (17-47%), phenols (25-60%), proline (82-94%), total soluble sugar (20-31%), DPPH activity (70-72%), and Zn uptake (91-106%). The doses of ZnOGA played an imperative role in determining the growth and productivity of the plant. Soil column studies showed that ZnOGA reduces Zn leaching by 52% compared to commercial Zn fertilizer. This study signifies the potential of ZnOGA to be applied as an eco-friendly and sustainable substitute for conventional Zn fertilizer minimizing Zn losses and Zn deficiency-related health problems in human populations.

MsNRAMP2 Enhances Tolerance to Iron Excess Stress in Nicotiana tabacum and MsMYB Binds to Its Promoter

Iron(Fe) is a trace metal element necessary for plant growth, but excess iron is harmful to plants. Natural resistance-associated macrophage proteins (NRAMPs) are important for divalent metal transport in plants. In this study, we isolated the MsNRAMP2 (MN_547960) gene from alfalfa, the perennial legume forage. The expression of MsNRAMP2 is specifically induced by iron excess. Overexpression of MsNRAMP2 conferred transgenic tobacco tolerance to iron excess, while it conferred yeast sensitivity to excess iron. Together with the MsNRAMP2 gene, MsMYB (MN_547959) expression is induced by excess iron. Y1H indicated that the MsMYB protein could bind to the "CTGTTG" cis element of the MsNRAMP2 promoter. The results indicated that MsNRAMP2 has a function in iron transport and its expression might be regulated by MsMYB. The excess iron tolerance ability enhancement of MsNRAMP2 may be involved in iron transport, sequestration, or redistribution.