Proteomic identification of small, copper-responsive proteins in germinating embryos of Oryza sativa.
OBJECTIVE
Although copper (Cu) is an essential micronutrient for plants and algae, excess Cu is toxic to most plants and can cause a wide range of deleterious effects. To investigate the response of rice (Oryza sativa) to Cu stress, a proteomic approach was used to analyse Cu stress-induced changes in the expression of low molecular-weight proteins in germinating rice seed embryos.


METHODS
Rice seeds were germinated in the presence or absence of 200 microm Cu for 6 d, and embryos, including newly formed shoots and radicles, were isolated. After proteins were extracted from the germinating embryos and separated by two-dimensional PAGE, 16 proteins in the 6- to 25-kDa range were identified using MALDI-TOF mass spectrometry.


CONCLUSIONS
Thirteen of the proteins identified, including metallothionein-like protein, membrane-associated protein-like protein, putative wall-associated protein kinase, pathogenesis-related proteins and the putative small GTP-binding protein Rab2, were up-regulated by Cu stress. Three proteins, a putative small cytochrome P450 (CYP90D2), a putative thioredoxin and a putative GTPase, were down-regulated by Cu stress. As far as is known, this study provides the first proteomic evidence that metallothionein and CYP90D2 are Cu-responsive proteins in plants. These findings may lead to a better understanding of plant molecular responses to toxic metal exposure.
Zhang
Hongxiao
H
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Lian
Chunlan
C
Shen
Zhenguo
Z
D003300:Copper / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D018525:Germination; D012275:Oryza / Q000196:embryology*; D010940:Plant Proteins / Q000378:metabolism*; D040901:Proteomics; D012639:Seeds / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D010940:Plant Proteins; D003300:Copper