ALBERT

Description: Background: Metallothioneins (MT) are low molecular weight, cysteine rich metal binding proteins, foundacross genera and species, but their function(s) in abiotic stress tolerance are not welldocumented. Results: We have characterized a rice MT gene, OsMT1e-P, isolated from a subtractive librarygenerated from a stressed salinity tolerant rice genotype, Pokkali. Bioinformatics analysis ofthe rice genome sequence revealed that this gene belongs to a multigenic family, whichconsists of 13 genes with 15 protein products. OsMT1e-P is located on chromosome XI, awayfrom the majority of other type I genes that are clustered on chromosome XII. Variousmembers of this MT gene cluster showed a tight co-regulation pattern under several abioticstresses. Sequence analysis revealed the presence of conserved cysteine residues in OsMT1e-P protein. Salinity stress was found to regulate the transcript abundance of OsMT1e-P in adevelopmental and organ specific manner. Using transgenic approach, we found a positivecorrelation between ectopic expression of OsMT1e-P and stress tolerance. Our experimentsfurther suggest ROS scavenging to be the possible mechanism for multiple stress toleranceconferred by OsMT1e-P. Conclusion: We present an overview of MTs, describing their gene structure, genome localization andexpression patterns under salinity and development in rice. We have found that ectopicexpression of OsMT1e-P enhances tolerance towards multiple abiotic stresses in transgenictobacco and the resultant plants could survive and set viable seeds under saline conditions.Taken together, the experiments presented here have indicated that ectopic expression ofOsMT1e-P protects against oxidative stress primarily through efficient scavenging of reactiveoxygen species.