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Science Papers Report Wild Wheatgrass Genome, More Efficient CRISPR Editing

By assembling and studying the genome of a wild relative of modern wheat, a team led by scientists from Shandong Agricultural University has identified a gene that drives resistance to a fungal disease, fusarium head blight (FHB), that devastates cultivated wheat crops. The scientists assembled the genome of Thinopyrum elongatum, a wild wheatgrass with known resistance to FHB, then identified and cloned the FHB resistance gene Fhb7. While the investigators found no Fhb7 homolog in any plant, its coding sequence shares overlap with a species of fungus that infects grass, suggesting that it entered the T. elongatum genome via horizontal gene transfer. The authors also show that engineering Fhb7 into wheat makes it resistant to FHB and the fungal disease crown rot without impacting yield.

A new approach to boosting the efficiency of precision CRISPR genome editing is reported by scientists at Peking University in Science Advances this week. The method involves site-specifically conjugating oligonucleotides to recombinant Cas9 protein containing a genetically encoded noncanonical amino acid with orthogonal chemical reactivity. In studies in human cell culture and mouse zygotes, the Cas9-oligonucleotide conjugates were shown to recruit an unmodified donor DNA template to the target site through base pairing, markedly increasing homology-directed repair efficiency, the researchers write. "This platform can be used to construct animal models and may have clinical applications," they add, noting that the chemically modified Cas9 proteins can complement chemically modified nucleic acids for improving the utility of CRISPR-Cas9-based genome editing.