The present study aims towards exam

The present study aims towards examining physiological, biochemical, anatomical and molecular traits in the high-yielding rice landraces of the eastern part of India at germination and seedling stage for low-to-moderate salinity stress tolerance. The germination percentages of 12 high-yielding varieties were analyzed under seven different concentrations of salt (0, 50, 100, 150, 200, 250 and 300 mM). Although, Lalat performed very well with 63.66% germination rate at 300 mM salt stress conditions, higher levels of salinity exhibited detrimental effects on other varieties. Hence, the salt concentrations 150 mM and 250 mM were optimally selected to screen the varieties for physiological and biochemical traits. The high-yielding varieties Lalat, Vamsi and Pratiksha exhibited lowest and similar trend of reduction over control (ROC) with relative water content (RWC) for 250 mM salt concentrations. The level of proline, increased with increasing concentrations of NaCl among most of the varieties and significantly high content was found in Vamsi. The chlorophyll content was high in Lalat as well as Pratiksha and reduction over control was highest in Vamsi under 150 mM salt concentrations. Interestingly, Lalat emerged as the most salt-tolerant landrace for physiological and biochemical traits. It was compared with salt-sensitive MTU7029 for anatomical changes on adaxial surface of the leaf blade and noticed out to be with less widened and few number of stomatal pores in response to salt stress. Further, expression analysis of salt-specific genes OsHKT1;5 and OsNHX1 resulted in identification of novel salt-stress responsive alleles/motifs like W-boxes, Box-W1, E2Fb and MBS in Lalat (salt-tolerant). Thus, the study disclosed the anatomical changes in adaxial surface of leaf and association of potential cis-acting regulatory elements (CARE) in regulation of salt-stress responsiveness in these two-contrasting rice landraces in the eastern part of India. Further, the study laid a foundation to explore transcriptional gene regulation to open-up the pathway towards crop improvement for salt-stress tolerance.