|YANG, LIMING - University Of Georgia
|JI, JIANHUI - Huaiyin Normal University
|WANG, HUI - University Of Georgia
|LUO, YUMING - Huaiyin Normal University
|HU, XIANGYANG - Chinese Academy Of Sciences
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2015
Publication Date: 2/26/2016
Citation: Yang, L., Ji, J., Harris-Shultz, K.R., Wang, H., Wang, H., Luo, Y., Hu, X. 2016. The dynamic changes of the plasma membrane proteins and the protective roles of nitric oxide in rice subjected to heavy metal cadmium stress. Frontiers in Plant Science. vol. 7. http://www.frontiersin.org/Journal/Abstract.aspx?s=1285&name=plant_proteomics&ART_DO=10.3389/fpls.2016.00190.
Interpretive Summary: Cadmium, a non-essential element to plant and animals, is a heavy metal that is present at toxic levels in the soil and water in many areas throughout the world. Cadmium in the soil is from industrial activities, municipal refuse, atmospheric disposition, and the use of phosphate fertilizers. Cadmium has damaging effects to crop growth and development but little is known about how rice responds to cadmium at the plasma membrane, the part of the cell that separates the cell from its environment. In this study, the rice plasma membrane proteome was examined when rice seedlings were exposed to cadmium or cadmium and nitric oxide, a signal molecule used by the plant to respond to environmental stresses. Exposure to cadmium or cadmium and nitric oxide caused a response in proteins at the plasma membrane involved in transport, signaling, metabolism, cell structure, and plant hormones. The enzyme phospholipase D was differentially regulated by cadmium exposure and examined further. Further experiments suggest that nitric oxide signaling is associated with the accumulation of antioxidant enzymes, glutathione (an antioxidant) and phosphatidic acid (the product of phospholipase D which regulates a wide array of cellular processes) which increases cadmium tolerance in rice by using the antioxidant defense system.
Technical Abstract: The heavy metal cadmium is a common environmental contaminant in soils and has adverse effects on crop growth and development. The signaling processes in plants that initiate cellular responses to environmental stress have been shown to be located in the plasma membrane (PM). A better understanding of the PM proteome in response to environmental stress might provide new insights for improving stress-tolerant crops. Nitric oxide (NO) is reported to be involved in the plant response to cadmium (Cd) stress. To further investigate how NO modulates protein changes in the plasma membrane during Cd stress, a quantitative proteomics approach based on isobaric tags for relative and absolute quantification (iTRAQ) was used to identify differentially regulated proteins from the rice plasma membrane after Cd or Cd and NO treatments. Sixty-six differentially expressed proteins were identified, of which, many function as transporters, ATPases, kinases, metabolic enzymes, phosphatases and phosphoslipases. Among these, the abundance of phospholipase D (PLD) was altered substantially after the treatment of both Cd and Cd and NO. Transient expression of the PLD fused with green fluorescent peptide (GFP) in rice protoplasts showed that the Cd and NO treatment promoted the accumulation of PLD in the plasma membrane. Addition of NO also enhanced Cd-induced PLD activity and the accumulation of phosphatidic acid (PA) produced through PLD activity. Meanwhile, NO elevated the activities of antioxidant enzymes and caused the accumulation of glutathione both which function to reduce Cd-induced H2O2 accumulation. Taken together, we suggest that NO signaling is associated with the accumulation of antioxidant enzymes, glutathione and PA which increases cadmium tolerance in rice via the antioxidant defense system.