Study On The Nutrient Mechanism Of Iron And Zinc In Elymus Sibiricus

Iron and zinc are essential microelements for plants.Elymus sibiricus is a perennial meso-xerophyte of sparse-bush,which is a model variety of Elymus and widely used for animal feed production and grassland restoration.It is important to study the nutrition mechanism of iron and zinc in Elymus sibiricus for further improving the nutritional value of Elymus sibiricus.Main research results are followed:?1?High concentration Fe²⁺significantly inhibited root and leaf growth,root hair development,Ca/Zn/K accumulation and Catalase,Ascorbic acid oxidase activity,but induced activity of Peroxidase,Glutathione reductase and Glutathione?Ascorbic acid biosynthesis.The root transcriptome analysis revealed that high concentration Fe²⁺induced expression of the glutathione S-transferase and F-box protein-coding genes,but inhibited the POD and IDS3 encoding genes.Increasing Zn²⁺and SiO₃^2-contents could significantly alleviate the growth inhibitory effect of high concentration of Fe²⁺.?2?Fe²⁺deficit inhibited leaf growth,chlorophyll biosynthesis and light energy transformation as well as electron transportation efficiency of the hydroponically grown Elymus sibiricus.Under Fe²⁺deficit condition,the photochemical reaction consuming light energy decreased and heat dissipation energy increased;the Fe²⁺deficit significantly inhibited activity of Superoxide dismutase,Peroxidase,Catalase,Ascorbate peroxidase,Glutathione reductase and contents of Dehydroascorbate and Ascorbic acid;the activities of Ferric chelate reductase and the contents of Malondialdehyde and Glutathione increased;expression of Cysteine protease and Aldehyde dehydrogenase encoding genes was up-regulated,but the AP-2 gene encoding complex of plant grid protein and the linker protein were down-regulated.?3?High concentration Fe²⁺could rescue the inhibitory effect of high concentration Zn²⁺on the growth of Elymus sibiricus mature plants.Fe²⁺promoted Zn accumulation in the root and leaf;Zn²⁺promoted Fe accumulation in the root but inhibited the leaf.High concentration Fe²⁺inhibited Mg and K accumulation in the root and leaf;Fe²⁺deficit promoted Mg and K accumulation in the leaf.Fe accumulation in Elymus sibiricus was inhibited by individual deficits of Mn²⁺,Mg²⁺,Ca²⁺,Cu²⁺,NO₃^-and high concentration of Mn²⁺?Mg²⁺?K⁺?PO₄^3-respectively;high concentration of Ca²⁺promoted the Fe accumulation;deficits and high concentration of Cu²⁺promoted Fe accumulation in the leaf;high concentration of NO₃^-promoted Fe accumulation in the leaf but inhibited the root.?4?Transcriptome analysis of the root identified eight genes encoding Fe²⁺and Zn²⁺transporters;expressing the genes numbered as DN67741?DN69480-2 and DN63800 could rescue the growth of the transporters deficit yeast mutant ZHY3??zrt1/?zrt2?,which indicates that these genes encodes proteins having transportation capacity.