This study investigates the gene expression profiles of salt-tolerant rice (var Pokkali) and salt-sensitive rice (var IR29) in response to salt stress. Using microarrays containing 1728 cDNAs from salt-stressed roots, the researchers analyzed transcript changes from 15 minutes to 1 week after salt shock. Salt stress at 150 mM NaCl reduced photosynthesis to one-tenth of its original level within minutes. At 15 minutes post-stress, Pokkali showed upregulation of transcripts, with approximately 10% of transcripts significantly upregulated or downregulated within one hour. The initial differences between control and stressed plants persisted but became less pronounced as plants adapted. The adaptive process was supported by similar analysis of IR29, where the immediate response was delayed and led to downregulation and death. The upregulated functions in Pokkali changed over time, with increased protein synthesis and turnover at early stages, followed by stress-responsive transcripts and defense-related functions later. After one week, upregulated transcripts indicated recovery. The study also compared physiological responses of Pokkali and IR29 under salt stress. Photosynthesis, stomatal conductance, and transpiration decreased rapidly in IR29, leading to irreversible wilting within 24 hours, while Pokkali maintained growth and recovered. Transcript profiles showed that Pokkali had a more rapid and effective response to salt stress, with upregulation of transcripts related to stress defense, protein synthesis, and transport facilitation. In contrast, IR29 showed delayed responses and eventual downregulation, leading to death. The microarray analysis revealed distinct transcript profiles for Pokkali and IR29, with different time points showing different categories of regulated transcripts. The study identified several key transcripts, including those involved in stress defense, protein synthesis, and transport. The results indicate that the initial phase of salt stress in Pokkali involves rapid transcriptional changes that help the plant adapt and recover, while IR29 lacks this adaptive capacity and succumbs to stress. The study highlights the importance of early transcriptional responses in salt tolerance and provides insights into the molecular mechanisms underlying salt stress adaptation in rice.This study investigates the gene expression profiles of salt-tolerant rice (var Pokkali) and salt-sensitive rice (var IR29) in response to salt stress. Using microarrays containing 1728 cDNAs from salt-stressed roots, the researchers analyzed transcript changes from 15 minutes to 1 week after salt shock. Salt stress at 150 mM NaCl reduced photosynthesis to one-tenth of its original level within minutes. At 15 minutes post-stress, Pokkali showed upregulation of transcripts, with approximately 10% of transcripts significantly upregulated or downregulated within one hour. The initial differences between control and stressed plants persisted but became less pronounced as plants adapted. The adaptive process was supported by similar analysis of IR29, where the immediate response was delayed and led to downregulation and death. The upregulated functions in Pokkali changed over time, with increased protein synthesis and turnover at early stages, followed by stress-responsive transcripts and defense-related functions later. After one week, upregulated transcripts indicated recovery. The study also compared physiological responses of Pokkali and IR29 under salt stress. Photosynthesis, stomatal conductance, and transpiration decreased rapidly in IR29, leading to irreversible wilting within 24 hours, while Pokkali maintained growth and recovered. Transcript profiles showed that Pokkali had a more rapid and effective response to salt stress, with upregulation of transcripts related to stress defense, protein synthesis, and transport facilitation. In contrast, IR29 showed delayed responses and eventual downregulation, leading to death. The microarray analysis revealed distinct transcript profiles for Pokkali and IR29, with different time points showing different categories of regulated transcripts. The study identified several key transcripts, including those involved in stress defense, protein synthesis, and transport. The results indicate that the initial phase of salt stress in Pokkali involves rapid transcriptional changes that help the plant adapt and recover, while IR29 lacks this adaptive capacity and succumbs to stress. The study highlights the importance of early transcriptional responses in salt tolerance and provides insights into the molecular mechanisms underlying salt stress adaptation in rice.