Salt Cress Genome Yields New Clues to Salt Tolerance

An international team, led by the Institute of Genetics and Developmental Biology, the Chinese Academy of Science, and BGI, the world's largest genomics organization, has completed the genomic sequence and analysis of salt cress (Thellungiella salsuginea), a wild salt-tolerant plant. The salt cress genome serves as a useful tool for exploring mechanisms of adaptive evolution and sheds new light on understanding the genetic characteristics underlying plant abiotic stress tolerance. The study was published online on July 9, 2012 in PNAS. Salt cress is a typical halophyte with high resistance to cold, drought, oxidative stresses, and salinity. Due to its small plant size, short life cycle, copious seed production, small genome size, and an efficient transformation, salt cress could serve as an important genetic model system for botanists, geneticists, and breeders to better explore the genetic mechanisms of abiotic stress tolerance. In the study, researchers sequenced the genome of salt cress (Shandong ecotype) using the paired-end Solexa sequencing technology. The genomic data yielded a draft sequence of salt cress with about 134-fold coverage. The final length of the assembled sequences amounted to about 233.7 Mb, covering about 90% of the estimated size (~260 Mb). A total of 28,457 protein-coding regions were predicted in the sequenced salt cress genome. Researchers found that the average exon length of salt cress and A. thaliana genes was similar, whereas the average intron length of salt cress was about 30% larger than that of A. thaliana. The evolutionary analysis indicated that salt cress and its close relative- Arabidopsis thaliana- diverged from approximately 7-12 million years ago. When tracing the differences between salt cress and A.
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