Detalle de: Transcriptome analysis of cadmium and mercury tolerant rhizobia and the impacts of tolerance on symbiosis with legumes

The Almadén mine region in Central Spain was in operation for nearly 2000 years and contaminated the surrounding environment with heavy metals. The host plants Medicago and Trifolium grow throughout the mine region and have adapted to high levels of heavy metals such as cadmium (Cd) and mercury (Hg). Currently, the genetic mechanisms of Cd or Hg tolerance are unknown in legumes such as Medicago or in symbiotic rhizobia. We have isolated and tested several strains of Sinorhizobium medicae (from Medicago host-plants) and Rhizobium leguminosarum (from Trifolium host-plants) that show wide variation in tolerance to heavy metals. Transcriptomics (RNA-seq) data for S. medicae and R. leguminosarum will provide useful functional understanding of genes involved in heavy metal detoxification and stress tolerance. A combination of genome assemblies of variable rhizobia strains (and two species) with transcriptomic data will provide a powerful comparative genomics analysis of genome structure, copy number variation, gene duplication, and differential gene regulation.