1a. Objectives (from AD-416):
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. Subobjective 1B: Identify and characterize genetic variation for root traits contributing to improved thermal tolerance. Subobjective 1C: Screen bioenergy sorghum accessions for high water use efficiency. Subobjective 1D: Characterize independent msd mutants optimized for sorghum grain yield improvement. Subobjective 1E: Isolate sorghum architecture mutants and genes to enhance hybrid vigor. 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. Subobjective 2B: Introgression of Ethiopian photoperiod sensitive germplasm with a U.S. adapted breeding line.
1b. Approach (from AD-416):
The Southern United States has large regions of crop production where temperatures can be extreme and rainfall is limited. Sorghum can be produced in these areas where corn falters because of sorghum’s high water use efficiency, as well as its superior tolerance to drought and high temperature stresses. Therefore, sorghum is poised to play a major role in crop production under stressful and more variable environments in the future. Sorghum offers a unique opportunity for improvement because of the availability of the vast National Plant Germplasm System (NPGS) collection (>40,000) of natural accessions that can be used to mine essential traits. Additionally, a pedigreed mutant library, derived from the inbred line BTx623, is available. A core collection of 256 lines from this library has been sequenced, revealing over 100,000 nonsynonymous mutations that can change the function of specific proteins. The mutant library also displays a great diversity of phenotypes, many of which may have potential in sorghum improvement, thus providing a unique resource for discovering novel traits in sorghum. Furthermore, sorghum employs the same efficient NADP-ME type of C4 photosynthesis as maize; therefore, it should have similar biomass and grain yields as maize. Due to lack of adequate resources to fully explore the existing sorghum resources for breeding, however, sorghum yield has been stagnant since the 1970s while maize yield continues to improve. There is an urgent need to mine both natural sorghum collections and mutant populations for superior traits to enhance sorghum biomass and grain yield to make it more profitable to grow sorghum. Some of the production problems sorghum growers currently face are cool soil and ambient air temperatures during early season planting, and pre- and post- flowering water stress. Enhanced field germination and excellent seedling vigor are hallmarks of cold tolerance. Recently, high seedling root biomass was identified as an important trait associated with early season cold tolerance of sorghum. Furthermore, early season cold tolerance is important because recent studies have indicated that earlier planting of sorghum can potentially minimize yield losses due to sugar cane aphid infestation. Therefore, research on sorghum to enhance early season germination and vigor is critical for improved sorghum production. The proposed research is relevant to the NP 301 Action Plan, Component 1: Crop Genetic Improvement, Problem Statements 1A: Trait discovery, analysis, and superior breeding methiods and 1B: New crops, varieties, and enhanced germplasm with superior traits.
3. Progress Report:
This is new project implemented in March 2018 to replace the terminating project 3096-21000-020-00D, Genetic Enhancement of Sorghum as a Versatile Crop. All plant materials that are needed to accomplish the milestones in 12 month period have been planted in the field.