Food security depends on staple cereal crops with durable disease resistance. Crop pathogens and pests reduce the yield and quality of agricultural production, at household, national, and global levels. Rust diseases significantly impact major staple food crops, including wheat (Triticum aestivum) and barley (Hordeum vulgare L). Rust pathogens display a high degree of host specificity. Often one formae specialis colonizes only a single cereal host species. Barley is a near nonhost for the wheat leaf rust, Puccinia triticina. The study of barley and its ‘near-nonhost status’ to wheat leaf rust has shown to be a promising way to identify genes associated with nonhost disease resistance. Two orthologous nonhost leaf rust disease resistance genes have been identified in barley, Hv-LecRK (otherwise known as Rphq2), found in cultivated barley and Hb-LecRK (Rph22) found in wild bulbous barley (Hordeum bulbosum). Both genes encode L-type lectin receptor-like kinases (LecRKs) that confer strong resistance to the non-adapted wheat leaf rust pathogen.
My thesis is based on the intriguing observation that the perception of non-adapted rust pathogens by LecRK genes is conserved across cultivated and wild barley, which raised questions over the functionality and potential uses of LecRK genes in molecular breeding. We identified in silico a total of thirty-two homologous genes to the Hv-LecRK disease resistance gene, derived from a pool of twelve candidate species ranging from rice to other agriculturally important cereal crops including oats, rye, and other distinctive dicot and monocot plant species. Using a transient expression system in Nicotiana benthamiana, we functionally validated all candidate homologs based on the co-infiltration of each candidate gene with three major rust pathogens (cultivated, wild barley, and wheat leaf rusts), and found twelve putatively novel nonhost resistant genes across five of the species evaluated.
This study represents the first allele mining effort to identify novel nonhost rust resistance alleles, with implications for both basic science and disease resistance breeding.
Natalia holds a Bachelor of Science degree in Biological Engineering from the National University of Colombia. After her graduation, she enrolled as an MS student at King Abdullah University of Science and Technology (KAUST) and subsequently joined the Cereal Genetics and Genomics group of Professor Simon Krattinger. Her research interests range from plant-pathogen interaction to molecular biology and resistance breeding. Currently, her efforts focus on identifying, functionally validating, and harnessing novel nonhost disease resistance genes, with the aim of using them in wheat breeding