The seminars take place on the Montpellier Institut Agro/INRAE Campus of La Gaillarde (2, place P. Viala Montpellier)

Tuesday August 1st  at 2 pm

Mohamed Shafi

National Centre for Biological Sciences (Tata Institute of Fundamental Research), Bangalore, India

Structural analysis of the sodium transporter HKT1;5 in Oryza species for new determinants of salinity tolerance

The level of Na+ accumulation in many plant species is inversely correlated to salinity tolerance. Members of the high-affinity K+ transporter (HKT) gene family are required for the regulation of Na+ accumulation in plants, which leads to salinity tolerance. HKT1;5 is a plasma membrane transporter that transports Na+ from root xylem vessels to shoots. OsHKT1;5 from Asian cultivars of rice has displayed allelic variation associated to salinity tolerance. Among wild rice species, this transporter has been studied mostly in the halophytic Oryza coarctata. We generated homology models for HKT1;5 transporter from Oryza species, noted variations in residues, and applied electrostatics to infer charge differences. We noticed that some variations in the amino acid residue at the pore entrance could have an impact on ion entry. Using molecular dynamics simulations, we found that variations in Na+ transport affinities were caused by a swapping of positively and negatively charged amino acid residues at the ion pore entrance of the transporter. The affinity and conductance of the ions were further verified by transport kinetics assays and site directed mutagenesis studies. Overall, the knowledge gained from our study could be used to develop rice crop varieties that are more resilient to salinity stress.

Contact : anne-alienor.very@cnrs.fr