Abstract
BackgroundGlobally, 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.Methodology/Principal FindingsUsing 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.ConclusionsExpression 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.
Highlights
Soil salinity is one of the major abiotic stresses leading to depression of crop yields [1]
We propose that the irrE gene might be used as a potentially promising transgene to improve abiotic stress tolerances in crop plants
We demonstrated here that expression of IrrE, a global regulator for extreme radiation resistance in Deinococcus radiodurans, confers significantly enhanced salt tolerance in both E. coli and Brassica napus
Summary
Soil salinity is one of the major abiotic stresses leading to depression of crop yields [1]. This problem is becoming more severe because of soil degradation, water shortage and global warming. Genes used in the transgenic approach have included those encoding functional and regulatory proteins [4,5]. Regulatory proteins were shown to be involved in control of gene expression and signal transduction in response to multiple stresses. They include transcription factors, protein kinases and enzymes involved in phosphoinositide metabolism. Previous efforts to improve salt tolerance in crop plants have met with only limited success. In Deinococcus radiodurans, the irrE gene encodes a global regulator responsible for extreme radioresistance
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