Genotypic Variability in Differential Expression of lea2 and lea3 Genes and Proteins in Response to Salinity Stress in Fingermillet (Eleusine coracanaGaertn) and Rice (Oryza sativaL.) Seedlings

Abstract

Some late embryogeny abundant (LEA) proteins, which are developmentally regulated in embryos, are also known to be expressed in meophytic tissues in response to osmotic stress. Here we report the extent of genetic variability in the level of expression of lea2 and lea3, under stress, in fingermillet and rice seedlings. In both species, the expression of lea genes was seen in the mesophytic tissue in response to salinity, partial dehydration and abscisic acid. Tolerant genotypes exhibited higher expression of rab16A and M3 that code for LEA2 proteins, than susceptible genotypes. A novel approach, that of raising antibodies against the conserved peptides of these proteins was used to study genetic variability in LEA protein levels. Since stress proteins are known to be expressed in response to mild, non-lethal induction-stress (Uma, Prasad and Udayakumar,Annals of Botany76: 43–49, 1995), we developed an optimum induction protocol for salinity stress in rice and fingermillet. We studied the quantitative differences in expression of these proteins by western blot and ELISA techniques in different genotypes. A positive correlation was found between LEA2 and LEA3 protein levels and the growth of seedlings during stress and recovery in both rice and fingermillet, indicating a possible relevance of these proteins in stress tolerance.