Location: Crop Germplasm Research
2019 Annual Report
Objectives
Objective 1: Utilize unadapted germplasm to increase genetic diversity of elite sorghum inbreds with improved agronomic performance through a collaborative effort involving public and private sector breeders.
Objective 2: Create nested association mapping resources from backcross-derived introgression populations to facilitate marker-assisted sorghum improvement.
Approach
A major challenge facing crop geneticists and breeders is how to develop strategies that combine genetic resources with the vast amount of knowledge and tools in genomics, marker-trait associations, high-throughput phenotyping platforms, genome editing, and bioinformatics to accelerate the rate of genetic gain in applied breeding programs. This project aims to utilize recent advances in high-throughput genotyping and phenotyping, knowledge of gene-to-phenotype trait relationships, whole genome profiles of genetic diversity within and between sorghum germplasm accessions, and emerging information management systems to acquire knowledge of sorghum genes and germplasm, and utilize this information to enhance the rate of genetic gain for complex traits such as grain yield through the development of new adapted breeding material. Utilizing a pre-breeding backcrossing scheme augmented with robust genomic and phenotypic tools, this project focuses on the improvement of sorghum hybrids by the introgression of desirable traits from unadapted and wild germplasm into elite sorghum inbreds, which will introduce new elite germplasm and favorable genes for complex traits, including grain yield, into sorghum breeding programs. The products of this research will include well-characterized elite sorghum inbreds with new genetic diversity and desirable traits, improved effectiveness of hybrid breeding programs through the introduction of new superior-performing diverse elite inbreds, and the development of public resources including backcross-nested association mapping (BC-NAM) populations and associated phenotypic and genotypic characterization to facilitate genomic-assisted breeding and innovative approaches for dissecting the genetic architecture of complex traits.
Progress Report
Work under this project during FY 2019, in collaboration with university partners, resulted in significant progress in sorghum germplasm development. Significant progress was made towards developing genetically diverse sorghum germplasm for use in applied breeding programs and for development of genetic resources for basic researchers (Objective 1). The research represents significant progress towards introducing novel genetic diversity into elite sorghum inbreds, and towards developing the genetic resources for genomic prediction studies that will enable the deployment of next generation genomic-based breeding tools in sorghum improvement programs. Specific accomplishments during FY 2019 include advancing and releasing to public breeders 16 new populations (50-80 lines per population, designated as BC1F2 lines) originating from backcrossing genetically diverse germplasm into elite inbreds designated as B and R (Objective 1). Significant progress in work initiated under the previous project was also achieved through a long-standing collaboration with university partners. The work resulted in the registration of 11 diverse elite sorghum lines for grain and silage hybrid production. This material represents elite germplasm derived from the Reinstated Sorghum Conversion program, which combines agronomic productivity with greater genetic diversity than presently exists in elite inbreds. Specific accomplishments during FY 2019 included advancing the best individuals from 16 BC1F2 and 24 BC1F3 populations (known as backcross-nested association mapping or BC-NAM populations) to develop new elite inbreds for grain hybrids and to facilitate genomic prediction studies for complex traits including grain yield (Objective 2). Along with advancing the BC-NAM populations, test cross hybrids were made between ~150 BC-NAM lines and 2 elite inbreds referred to as tester lines. This breeding activity will allow for evaluation of BC-NAM lines in hybrid yield trials (Objective 2). Work by this project in FY 2019 significantly advanced the genetic advancement of sorghum to facilitate the productive and profitable use of new sorghum types by U.S. farmers.
Accomplishments
1. Novel genetic diversity in unadapted sorghum accessions. Sorghum is an important grain crop in many areas of the U.S. and other temperate regions worldwide. However, much of the potentially valuable sorghum germplasm is tropical in origin and does not successfully flower and produce seed in temperate environments, making these sources of genetic variability unavailable to many of the world's sorghum producing areas. ARS scientists at College Station, Texas, working with university collaborators, utilized classical plant breeding techniques and genomics tools to introgress novel genetic diversity into elite sorghum inbreds with the objective of making new elite inbreds with superior hybrid performance. From large panels of converted tropical germplasm and sorghum populations known as backcross-nested association mapping or BC-NAM populations, elite sorghum plants with potentially superior breeding value were selected and evaluated for the development of higher producing sorghum hybrids for farmers in the U.S. and worldwide.
Review Publications
Chougule, K., Wang, L., Stein, J., Wang, X., Devisetty, U., Klein, R.R., Ware, D. 2018. Improved RNA-seq workflows using cyVerse cyberinfrastructure. Current Protocols in Bioinformatics. 63(1):e53. https://doi.org/10.1002/cpbi.53.
Patil, N., Pugh, N., Klein, R.R., Martinez, H., Martinez, R., Rodriguez-Herrera, R., Rooney, W., Klein, P. 2019. Heritability and quantitative trait loci of composition and structural characteristics in sorghum grain. Journal of Crop Improvement. 33(1):1-24. https://doi.org/10.1080/15427528.2018.1536006.
