Vol. 33, No. 2, April-June 2015 1411 Comparative Analysis of Salinity Responsive Expression Pattern of Putative Candidate Genes... Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, India – 641 003. *Corresponding Author E-mail: raveendrantnau@gmail.com IJTA © Serials Publications Hifzur Rahman, Valarmathi R., Jagadeeshselvam N. and Raveendran Muthurajan* ABSTRACT: Rice (Oryza sativa), a salt-sensitive species, whereas finger millet (Eleusine coracana L.) another member of poaceae family closely related to rice is a resilient cereal known for its superior level of tolerance against drought and salinity. In this study comparative physiological and molecular analysis was done to see the effects of NaCI stress on contrasting genotypes of rice and finger millet. Gas exchange parameters measured with LICOR64 has shown higher photosynthetic rate, stomatal conductance and transpiration rate under salinity stress conditions in tolerant finger millet genotype as compared to susceptible finger millet and both the rice genotypes. Northern blot analysis using heterologous probes of rice shown salinity specific upregulation of AKT 1 like potassium channel protein in finger millet genotypes. DREB1A transcription factors was found to be upregulated in response to salinity stress specifically in finger millet genotypes whereas DREB 2 was upregulated in both susceptible rice and finger millet genotypes than the tolerant ones under stress condition. Heterologous probes for genes encoding Group 1 and Group 3 LEA protein and glycosyl transferase were found to be upregulated specifically in salinity tolerant finger millet genotype where as it was found to be downregulated in both rice and susceptible finger millet genotype. The study gives an insight into the existence of similar orthologous molecular responses in finger millet and rice under salinity stress. Keywords: Finger Millet, Salinity, Northern Blotting, Heterologous Probes, Photosynthesis, Gas Exchange. INTRODUCTION Salinity represents a strong limitation for agricultural production worldwide, especially in arid and semi- arid areas and restricts efficient utilization of available land resources. Around 45 million hectares (M ha) of irrigated land, accounting 20% of total land area have been affected by salinity worldwide and approximately 1.5 M ha are taken out of production each year due to high salinity levels in the soil (Pitman, and Läuchli 2002; Munns, and Tester 2008). Most of the cereal crops are sensitive to salinity and have limited amount of genetic variation for salinity tolerance in their germplasm. Rice a staple food crop for half of the world population has been rated as a salt sensitive crop (Shannon, et al., 1998). Hence genetic improvement of crops for their tolerance against salinity will be helpful in achieving targeted food production to meet the demands of growing population. Conventional plant breeding approaches have resulted in limited success in developing salt tolerant crop varieties due to limited understanding on the complexity of salt tolerance mechanisms, difficulties involved in selection of component traits and presence of low genetic variation in major crops. Reproductive barriers and linkage drag in turn adds the stumbling block in transferring genes from wild relatives into domesticated cultivar through conventional breeding. Responses against salinity stress involve many molecular processes such as ion homeostasis (membrane proteins involved in ionic transport), osmotic adjustment and water regime regulation (osmolytes) and scavenging of toxic compounds (Munns, and Tester 2008). During recent years, considerable attention has been given towards elucidating the molecular basis of salt tolerance in crop plants. Utilization of modern genetic approaches and high-throughput methods of functional genomics have resulted in elucidation of salt tolerance mechanisms, especially salt ion signaling and