Rapid Cloning of Disease Resistance Genes in Wheat

Abstract

AbstractWheat is challenged by rapidly evolving pathogen populations, resulting in yield losses. Plants use innate immune systems involving the recognition of pathogen effectors and subsequent activation of defense responses to respond to pathogen infections. Understanding the genes, genetic networks, and mechanisms governing plant-pathogen interactions is key to the development of varieties with robust resistance whether through conventional breeding techniques coupled with marker selection, gene editing, or other novel strategies. With regards to plant-pathogen interactions, the most useful targets for crop improvement are the plant genes responsible for pathogen effector recognition, referred to as resistance (R) or susceptibility (S) genes, because they govern the plant’s defense response. Historically, the molecular identification of R/S genes in wheat has been extremely difficult due to the large and repetitive nature of the wheat genome. However, recent advances in gene cloning methods that exploit reduced representation sequencing methods to reduce genome complexity have greatly expedited R/S gene cloning in wheat. Such rapid cloning methods referred to as MutRenSeq, AgRenSeq, k-mer GWAS, and MutChromSeq allow the identification of candidate genes without the development and screening of high-resolution mapping populations, which is a highly laborious step often required in traditional positional cloning methods. These new cloning methods can now be coupled with a wide range of wheat genome assemblies, additional genomic resources such as TILLING populations, and advances in bioinformatics and data analysis, to revolutionize the gene cloning landscape for wheat. Today, 58 R/S genes have been identified with 42 of them having been identified in the past six years alone. Thus, wheat researchers now have the means to enhance global food security through the discovery of R/S genes, paving the way for rapid R gene deployment or S gene elimination, manipulation through gene editing, and understanding wheat-pathogen interactions at the molecular level to guard against crop losses due to pathogens.