Combined multi-omics and physiological approaches to elucidate drought-response mechanisms of durum wheat

Osvin Arriagada ¹ Claudio Meneses ² Romina Pedreschi ³ Gerardo Nuñez-Lillo ³ Carlos Maureira ² Samantha Reveco ² Valentina Villarroel ² Ursula Steinfort ² Francisco Albornoz ² Patricia Cabas-Lühmann ² Manuela Silva ⁴ IVAN A MATUS ⁵ Andrés Ricardo Schwember ^2*

• ¹ Center for Processed Food Studies, Talca, Chile
• ² Pontificia Universidad Católica de Chile, Santiago, Chile
• ³ Pontificia Universidad Católica de Valparaíso, Valparaiso, V Valparaíso Region, Chile
• ⁴ University of Lisbon, Lisbon, Lisboa, Portugal
• ⁵ Quilamapu Regional Research Center, Institute of Agricultural Research (INIA), Chillan, Chile

Durum wheat is the most important cereal in the Mediterranean regions, where drought negatively affects grain yield. This study performed a multi-omics and integration analysis in conjunction with physiological trials to improve our understanding of drought tolerance mechanisms of durum wheat. Genome-wide association studyies (GWAS) for yield components was performed onwere tested in a panel of 225 elite durum wheat genotypes evaluated in eight sites under irrigated and rainfed conditions. Nine marker-trait associations were detected across all 8 environments and were grouped into three QTL clusters (QTL_2A_TGW/GPS.1, QTL_2A_TGW/GPS.2, and QTL_2B_TGW/GPS.1), explaining between 5.15% and 14.29% of the phenotypic variation. One drought tolerant (QUC 3678-2016) and one susceptible (BRESCIA) genotype were identified based on physiological parameters (net photosynthesis, intracellular CO2 content, transpiration, and stomatal conductance) and grain yield under drought conditions. RNA-seq analysis showed that the genes regulated were mainly enriched in several processes, such as response to salicylic acid, plant organ senescence, synthesis of secondary metabolites, and immune response. Metabolic analysis showed that drought increased the contents of amino acids, sugars, and organic acids. The integration analysis identified 30 genes and six metabolites in the root and 30 genes and 10 metabolites in leaves as the Con formato: Inglés (Estados Unidos) Con formato: Inglés (Estados Unidos) Con formato: Subíndice 2 primary variables in the drought-tolerant genotype, in which L-Proline was an important metabolite that allowed differentiating those two contrasting genotypes. A WRKY transcription factor was also positioned on the stable QTL QTN_2A_TGW/GPS.1 associated with the GENE-1342_238 SNP marker. These results open an opportunity to use new biomarkers in durum wheat breeding programs to develop resilient and high-yielding cultivars and ensure food security under water deficit conditions.