Researchers Profile Wheat Gene Helping Plant Dodge Damaging Virus

For a paper slated to appear in the Proceedings of the National Academy of Sciences this week, researchers from Japan, China, France, and Australia characterize a gene called Ym2 that appears to bolster resistance to the wheat yellow mosaic virus (WYMV), an economically damaging virus transmitted to wheat roots by spores from the soil-borne fungus Polymyxa graminis. Using mechanical inoculation experiments, positional cloning, RNA in situ hybridization, and other experiments, the team linked Ym2 to a chromosome 3 region that overlaps with a polymorphic gene known as CDS618 that codes for coiled-coil-, nucleotide-binding site-, and leucine-rich repeat motif-containing protein implicated in disease resistance. Although the root-expressed Ym2 gene and a more widely expressed gene paralog turned up in the wheat plant's wild Aegilops sharonensis and A. speltoides relatives, the authors note, a more detailed phylogenetic analysis hints that it was passed down to the bread wheat plant through the A. sharonensis ancestral plant. "The analysis has provided novel information as to how the Ym2 region arose during the course of the evolution of cultivated wheat," they write, adding that the current results suggest that "organ-specific expression of Ym2 was acquired by its physical proximity to CDS617, given that certain closely linked genes share enhancers of DNA or chromatin as well as chromatin remodeling."