DIFFERENTIAL CHANGES IN GLUTAMINE-SYNTHETASE ISOFORMS IN THE COTYLEDONS OF GERMINATING CHICKPEA (CICER-ARIETINUM L) SEEDS IN RESPONSE TO OSMOTIC-STRESS

Changes in seedling growth and Glutamine Synthetase isoforms in cotyle dons of germinating chickpea (Cicer arietinum L.) seeds were studied i n response to osmotic stress. PEG-induced osmotic stress adversely aff ected the seedling growth. After Gh of imbibition, only one GS isoform was detected in the cotyledons while at all subsequent stages both cy tosolic (GS(1)) and plastidic (GS(2)) isoforms were observed. GS(1) co nstituted a major proportion of total GS activity in the cotyledons of control-germinated seeds but under osmotic stress GS(1) activity decr eased, whereas GS(2) activity increased. Implications of these finding s in stress adaptation of germinating chickpea seeds are discussed.