Enhancing Efficiency In Wheat Triticum Aestivum L Breeding For Abiotic And Biotic Stress Resistance Using Novel Physiological And Genetic Approaches PDF Download

By 2050 global demand for wheat (Triticum aestivum L.) is predicted to grow by 60%. To meet this demand, annual genetic gains must increase by 1.4%, and withstand increasing environmental stresses. The goal of the work herein was to use new phenomic, genomic and molecular tools to identify novel genomic regions associated with eyespot (Oculimacula yallundae and O. acuformis) disease resistance, drought tolerance and yield stability. To identify novel genomic regions associated with eyespot resistance in winter wheat, disease susceptibility was evaluated in two PNW winter wheat panels (n= 469, 399) and genome-wide association mapping was conducted. Of the 92 marker trait associations identified, the seven most significant cumulatively reduced eyespot disease response. As breeding lines were used, the results can be used for rapid introgression of resistance alleles into elite lines. The second objective of this work was to evaluate phenotypic associations of physiological traits and yield under rain-fed conditions to identify traits for use in breeding. 700 lines of the spring wheat nested association mapping panel were evaluated for water use efficiency, plant water status, photosynthetic and photoprotective mechanisms and grain yield over three years. Six traits had a cumulative effect on increasing yield: plant water status, plant height, photosynthetic capacity, vegetative green index, water used efficiency and days from sowing to heading. The physiological traits identified can be used to improve selection efficiency and yield stability under variable rain-fed conditions. The third objective of this work was to identify genomic regions associated with the water-use efficiency, plant water status, leaf health and photosynthesis. 650 lines of the spring wheat NAM panel were evaluated for these traits and grain yield under rain-fed conditions and joint inclusive composite interval mapping and genome-wide association analysis was conducted. The seven most significant grain yield QTL identified, located on chromosomes 1A, 1B, 2B, 4B, 5B, and 7B, were found in multiple environments and were associated with multiple physiological traits. This study helps reveal the genetic architecture of drought tolerance and grain yield and can be used to improve the efficiency of breeding under variable water-limited conditions.