Genetics basis of root architecture variation in barley (Hordeum vulgare L.)

Climate change poses significant threats to global agriculture, potentially reducing both the yield and quality of important crops like barley. With a projected human population of 10 billion in an environmental undergoing degradation, addressing these challenges requires a delicate balance between agricultural productivity and environmental sustainability. Root System Architecture (RSA) plays a crucial role in soil exploration, influencing a plant's access to water and nutrients. Exploring and manipulating RSA offers promising opportunities to advance both crop production and ecosystem management practices. This study consists of three chapters. In the first chapter, we report the results of a Genome Wide Association Study on RSA using the WHEALBI barley collection. Coupling phenotypic datasets for seven seminal root traits with genotypic data derived from exome capture revealed 106 QTLs, along with candidate genes associated with each trait. In the second and third chapters, we focused on screening the TILLMore collection. Specifically, in the second chapter, we phenotypically characterized 13 root hair mutants and mapped the causal gene of the root hairless mutant (TM1291) to a bHLH transcription factor. In the third chapter, we report the characterization of the gravitropic root mutant TM1354, which exhibited a narrow root angle and a faster response to gravity compared to the wild type. Mapping by sequencing enabled us to narrow down the causal locus on chromosome 6, in a region encompassing five candidate genes. The mutants and genes identified in this study likely play key roles in plant stress response, especially in water and soil nutrients deprivation. Thus, our findings could enhance our understanding of crop adaptation to these types of abiotic stresses. Our results also confirm the utility of the TILLMore collection in supplying plant materials for investigating the molecular foundations of traits of breeding and agronomic interest.