IrrE, a global regulator of extreme radiation resistance in Deinococcus radiodurans, enhances salt tolerance in Escherichia coli and Brassica napus.
BACKGROUND
Globally, about 20% of cultivated land is now affected by salinity. Salt tolerance is a trait of importance to all crops in saline soils. Previous efforts to improve salt tolerance in crop plants have met with only limited success. Bacteria of the genus Deinococcus are known for their ability to survive highly stressful conditions, and therefore possess a unique pool of genes conferring extreme resistance. In Deinococcus radiodurans, the irrE gene encodes a global regulator responsible for extreme radioresistance.


RESULTS
Using plate assays, we showed that IrrE protected E. coli cells against salt shock and other abiotic stresses such as oxidative, osmotic and thermal shocks. Comparative proteomic analysis revealed that IrrE functions as a switch to regulate different sets of proteins such as stress responsive proteins, protein kinases, glycerol-degrading enzymes, detoxification proteins, and growth-related proteins in E. coli. We also used quantitative RT-PCR to investigate expression of nine selected stress-responsive genes in transgenic and wild-type Brassica napus plants. Transgenic B. napus plants expressing the IrrE protein can tolerate 350 mM NaCl, a concentration that inhibits the growth of almost all crop plants.


CONCLUSIONS
Expression of IrrE, a global regulator for extreme radiation resistance in D. radiodurans, confers significantly enhanced salt tolerance in both E. coli and B. napus. We thus propose that the irrE gene might be used as a potentially promising transgene to improve abiotic stress tolerances in crop plants.
Pan
Jie
J
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Crop Biotechnology, Ministry of Agriculture, Beijing, China.
Wang
Jin
J
Zhou
Zhengfu
Z
Yan
Yongliang
Y
Zhang
Wei
W
Lu
Wei
W
Ping
Shuzhen
S
Dai
Qilin
Q
Yuan
Menglong
M
Feng
Bin
B
Hou
Xiaoguang
X
Zhang
Ying
Y
Ma
Ruiqiang
R
Liu
Tingting
T
Feng
Lu
L
Wang
Lei
L
Chen
Ming
M
Lin
Min
M
D001426:Bacterial Proteins / Q000378:metabolism*; D029688:Brassica napus / Q000235:genetics / Q000502:physiology*; D019610:Cytoprotection; D034301:Deinococcus / Q000378:metabolism*; D004926:Escherichia coli / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D005990:Glycerol / Q000378:metabolism; D009997:Osmotic Pressure; D010802:Phylogeny; D030821:Plants, Genetically Modified; D040081:Protein Array Analysis; D011836:Radiation Tolerance; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055049:Salt Tolerance / Q000502:physiology*; D013312:Stress, Physiological / Q000235:genetics
D001426:Bacterial Proteins; D005990:Glycerol