NP 301 Plant Genetic Resources, Genomics, and Genetic Improvement
Discovery and Improvement of Traits to Enhance Sorghum as a Multiple Purpose Crop
Sorghum is a C4 crop with high water use efficiency, superior resilience to high temperature and drought stresses, and the ability to thrive on poor soils. Recently, sorghum has been proposed as a prominent bioenergy feedstock and has attracted investment from the Department of Energy for research and development as a renewable biomass crop. However, sorghum grain yield has been stagnant since the 1970s, far behind maize under favorable conditions. Many traits that are proven successful in boosting yield in other crops have not been adequately explored in sorghum. In this proposed project, we will search for and characterize these traits, including cold tolerance, root traits, water use efficiency, increased grain number per panicle, orthogonal semi-dwarf, and erect leaf from collections of natural accessions and mutant populations. These traits will be introgressed into elite sorghum lines. We will also combine several advantageous traits into individual inbred lines through molecular marker-assisted trait pyramiding. The project will deliver to the sorghum industry a collection of novel pre-breeding materials geared to enhance sorghum varieties that can eventually break the yield stagnation and sustain improved grain production for American agriculture.
OBJECTIVE 1: Discover and characterize superior traits from natural collections and a mutant population to enhance abiotic stress tolerance, yield potential, and stability of grain, forage, and bioenergy sorghum.
Subobjective 1A: Identify new sources of thermal tolerance within diverse Ethiopian germplasm (Emendack, Hayes)
Subobjective 1B: Identify and characterize genetic variation for root traits contributing to improved thermal tolerance (Burow).
Subobjective 1C: Screen bioenergy sorghum accessions for high water use efficiency (Burke).
Subobjective 1D: Characterize independent msd mutants optimized for sorghum grain yield improvement (Xin, Hayes).
Subobjective 1E: Isolate sorghum architecture mutants and genes to enhance hybrid vigor (Xin, Hayes, Emendack).
OBJECTIVE 2: Develop new sorghum lines with superior early season cold and drought tolerance, and improved hybrid yield.
Subobjective 2A: Develop superior sorghum inbred lines through marker-assisted trait pyramiding (Burow, Xin, Hayes).
Subobjective 2B: Introgression of Ethiopian photoperiod sensitive germplasm with a U.S adapted breeding line (Hayes).
NEED FOR RESEARCH
Problem to be Solved: Sorghum and maize have the same NADP-malic type of highly efficient C4 photosynthetic pathway; however, sorghum biomass and grain yield have lagged far behind maize under favorable conditions. Since the 1970s, sorghum yield advancement has been stagnant while the yield of maize hybrids continues to advance after the full adoption of hybrids. One reason for this stagnation is that sorghum is predominantly grown in low rainfall areas with little supplement irrigation because of its resilience to multiple abiotic stresses. The goal of this project is to find traits that may break this stagnation, and enhance sorghum yield and overall stress tolerance (partly encompassing tolerance to sugarcane aphids).
The lack of targeted traits for improvement may be one of the contributing factors to the overall yield plateau. As an example, the proven architecture traits, such as semi-dwarf and erect leaf traits, that significantly advanced the grain yield of wheat, rice, and maize have not been available in sorghum. Sorghum has multiple dwarf loci, but none corresponds to the orthogonal dwarf genes used in wheat or rice during the Green Revolution. In the proposed research, we will search for strategic traits from collections of natural accessions and mutant populations to attempt to break this yield stagnation. These traits include high water use efficiency, efficient root systems, increased grain numbers per panicle, and ideal height and leaf angle to maximize utilization of solar radiation and water resource and ideal biomass distribution to achieve high and stable yields. We will introduce these new traits into sorghum elite inbred lines for creating new sorghum hybrids with high yield potential and enhanced stress tolerance.