GENOTYPIC VARIABILITY IN DIFFERENTIAL EXPRESSION OF LEA2 AND LEA3 GENES AND PROTEINS IN RESPONSE TO SALINITY STRESS IN FINGERMILLET (ELEUSINE-CORACANA GAERTN) AND RICE (ORYZA-SATIVA L.) SEEDLINGS

Some late embryogeny abundant (LEA) proteins, which are developmentall y regulated in embryos, are also known to be expressed in meophytic ti ssues in response to osmotic stress. Here we report the extent of gene tic variability in the level of expression of lea2 and lea3, under str ess, in fingermillet and rice seedlings. In both species, the expressi on of lea genes was seen in the mesophytic tissue in response to salin ity, partial dehydration and abscisic acid. Tolerant genotypes exhibit ed higher expression of rab16A and M3 that code for LEA2 proteins, tha n susceptible genotypes. A novel approach, that of raising antibodies against the conserved peptides of these proteins was used to study gen etic variability in LEA protein levels. Since stress proteins are know n to be expressed in response to mild, non-lethal induction-stress (Um a, Prasad and Udayakumar, Annals of Botany 76:43-49, 1995), we develop ed an optimum induction protocol for salinity stress in rice and finge rmillet. We studied the quantitative differences in expression of thes e proteins by western blot and ELISA techniques in different genotypes . A positive correlation was found between LEA2 and LEA3 protein level s and the growth of seedlings during stress and recovery in both rice and fingermillet, indicating a possible relevance of these proteins in stress tolerance. (C) 1998 Annals of Botany Company