Laminar library screen

A method of screening libraries of variant genes in plant leaves using a plant viral vector to identify a gene of interest, the method comprising:

• a) inoculating plant leaves with a library of viruses expressing variant genes;
• b) allowing sufficient time for a plurality of infected foci to form;
• c) harvesting a leaf with infected foci, the leaf having two opposing faces;
• d) sticking one face of the leaf to a sticky support material to immobilize the leaf and leaving the opposing face of the leaf exposed to form an exposed face;
• e) abrading the exposed face of the leaf with granular material to form an abraded face;
• f) appressing the abraded face to a semi-solid substrate and allowing transfer of material from the leaf into the semi-solid substrate;
• g) removing the leaf from the semi-solid substrate;
• h) performing an assay on the semi-solid substrate to identify an infected focus of interest;
• i) recovering virus of interest corresponding to the infected focus of interest;
• j) recovering nucleic acid from the virus of interest;
• and
• k) identifying the gene of interest from the nucleic acid.