Mining Vavilov’s Treasure Chest of Wheat Diversity for Resistance to Leaf Rust

We performed the first genomic characterization of bread wheat accessions from the N.I. Vavilov Institute of Plant Genetic Resources in St Petersburg, Russia. This analysis focused on a panel of 295 genotypes, including landraces, cultivars and breeding lines, originally collected by Vavilov and his colleagues from 28 countries around the world during the period 1920-1990. The panel was genotyped using the genotyping-by-sequencing Diversity Arrays Technology platform (DArTseq). A high degree of novel alleles were detected, which were absent in Australian and CIMMYT elite germplasm. Such allelic diversity is needed to develop more productive cultivars, particularly in the face of climate change and rapidly evolving pests and diseases. A major disease of wheat crops worldwide is leaf rust, caused by rapidly evolving fungal pathogen Puccinia triticina. Thus, breeders require a constant supply of new and durable sources of genetic resistance. Here, we present a case study that aimed to identify novel sources of leaf rust resistance in the Vavilov wheat diversity panel. GWAS was performed using phenotypic data collected across five environments and multiple pathotypes. A total of 36 QTL were detected: 8 associated with seedling resistance and 24 associated with adult plant resistance. Using the rapid generation advance technology “speed breeding”, which enables up to six generations per year, we are accelerating the transfer of the novel resistances into cultivars suitable for the major wheat growing regions of Australia. The seed and DArTseq markers for the Vavilov diversity panel provide an open-access resource to harness novel allelic diversity in wheat.