Proteomic investigation of Zn-challenged rice roots reveals adverse effects and root physiological adaptation

Abstract

Aims Understanding the molecular responses of plant roots to the challenging environment contributes to engineering plants with improved stress tolerance. However, little has been done to understand rice (Oryza sativa L.) roots response to the toxic concentration of zinc (Zn) at the proteomic level. This study explored proteomic responses of young rice roots 5-6 days after sowing to 765 µM of Zn in a hydroponic set-up after 4-day exposure.Methods Dye staining method and spectrophotometry were chosen for physiological response investigations. ICP-MS was used to determine metal content in rice seedlings. Two-dimensional gel electrophoresis was used for the proteomic study of root tissue.Results Elevated Zn reduced Mg translocation to the shoots and Mn uptake, decreased plant growth, and increased cell death of roots. Zn stimulated the biosynthesis of glutathione but decreased ROS and malondialdehyde levels. In total, 42 Zn-responsive proteins were identified. Proteins involved in redox regulation, defense response, sulfur metabolism, and proteolysis were induced, while those of energy production and cell wall biogenesis were decreased.Conclusion Roots of O. sativa seedlings could tolerate certain Zn excess (765 µM Zn for 4 days) by stimulating nutrient recycling and glycolysis, and production of defensive metabolites and proteins to maintain ion and redox homeostasis. Besides, adenosylhomocysteinase (AHCY) down-regulation may contribute to balanced transmethylations, and methionine salvage pathway appears important for the adaptation to Zn. Our results provide some new insight into the complex metabolic response of rice roots to Zn stress, which is related to both stress and defense mechanisms.

Synthesis and Characterization of Chitosan Oligosaccharide Selenium Nanoparticles and Selenium Enrichment Evaluation and Mechanism on Soybean Sprouts

“…56 On the other hand, excess zinc ions inhibited root growth, impinged on regions of root elongation (zinc-induced cracking), reduced the ability to take up nutrients, and even led to cell death. 57,58 This may also explain the decreased K, Mg, Cu, and Fe concentrations in the radicle mentioned earlier. 59 For the hypocotyl of soybean sprouts, the selenium enrichment promoted the increase in Ca, Mg, P, Cu, and Zn up to a certain range.…”

“…for binding at many sites (e.g., major absorption regions or loading regions of roots) . On the other hand, excess zinc ions inhibited root growth, impinged on regions of root elongation (zinc-induced cracking), reduced the ability to take up nutrients, and even led to cell death. , This may also explain the decreased K, Mg, Cu, and Fe concentrations in the radicle mentioned earlier …”

Integration of transcriptomic and proteomic analyses reveals several levels of metabolic regulation in the excess starch and early senescent leaf mutant lses1 in rice

“…6 ). SUS (sucrose synthase 1) overexpression provides more UDP-glucose and fructose for various metabolic pathways [ 40 ], while FRK (fructokinase-2) upregulation catalyses the formation of more fructose-6-phosphate derived from fructose and channels sucrose into the glycolytic pathway [ 41 ]. It could be speculated that the substrate of glycolysis is more biased towards fructose and sucrose rather than glucose derived from starch due to the accumulation of starch in the chloroplast reduces the transport of maltose and glucose to the cytoplasm.…”

Integration of Transcriptomic And Proteomic Analyses Reveals Several Levels of Metabolic Regulation In The Excess Starch And Early Senescent Leaf Mutant lses1 In Rice

“…5). SUS (sucrose synthase 1) overexpression provides more UDP-glucose and fructose for various metabolic pathways [30], while FRK (fructokinase-2) upregulation catalyses the formation of more fructose-6-phosphate derived from fructose and channels sucrose into the glycolytic pathway [31]. It could be speculated that the substrate of glycolysis is more biased towards fructose and sucrose rather than glucose derived from starch due to the accumulation of starch in the chloroplast, which reduces the transport of maltose and glucose to the cytoplasm.…”