Molecular characterization of OsCURT1A from upland rice in response to osmotic stress

CURT1 proteins in 'Arabidopsis thaliana' have been reported to be important for inducing grana curvature. Currently, we have identified transcript encoding CURT1A from 'Oryza sativa' cv. indica through RNA-seq analysis and characterised using heterologous system in Arabidopsis. The 'OsCURT1A' gene shares 80% of its amino acid sequence with Arabidopsis 'AtCURT1A'. Phylogenetic analysis revealed that the 'OsCURT1A' is also closely related to the CURT1 proteins in other choloroplast- conatining organisms. In silico analysis of OsCURT1A promoter shows that several cis-elements related to stress are present in the 5' upstream from the coding region. Under normal conditions, there were no notable changes in the phenotype and chlorophyll a;b ratio between three Arabidopsis genotypes, which were overexpressed (35S::'OsCURT1A'), T-DNA insertional mutant line ('atcurt1a'), and Wild type (Col-0). However, overexpression of 'OsCURT1A' under salinity condition demonstrate high chlorophyll a:b compared to Col-0, whereas, the lack of atcurt1a gene in the mutant line showed reduced chlorophyll a:b ratio. These results indicate that the 'OsCURT1A' might have a function as salt-stress related gene, which may indirectly regulate the chlorophyll a:b ratio. Therefore, 'OsCURT1A' can be used as a potential candidate for salinity stress tolerance in crop improvement.