Location: Crop Germplasm Research
2021 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 Fiscal Year (FY) 2021, in collaboration with university and ARS partners, resulted in significant progress in sorghum germplasm development, which addressed the four FY 2021 milestones. Advancements were made towards developing genetically diverse sorghum germplasm through introgression breeding for use in applied breeding programs, and for development of genetic resources for basic researchers. The research represents significant progress towards introducing novel genetic diversity into elite sorghum inbreds, and towards developing the genetic resources for genomic prediction efforts that will enable the deployment of next generation genomic-based breeding tools in sorghum improvement programs. Specific accomplishments during FY 2021 in support of Objective 2 include multi-location trials of testcross hybrids of elite BC1F4 selections originating from Backcross-Nested Association Mapping (BC-NAM) populations; this data is being used to construct genomic prediction models for grain yield. Progress under Objective 2 also included generational advancement and phenotyping of the best inbreds from 30 BC1F5 BC-NAM populations to develop new elite inbreds for grain and forage hybrids. To meet additional Objective 2 milestones, phenotypic data on 30 BC1F4 BC-NAM populations was collected by ARS researchers at Lubbock, Texas, and university researchers at Clemson University, Kansas State University, and The University of California. This data is presently being curated through a germplasm registration article. Under Objective 1, specific accomplishments during FY2021 include advancing and selecting three BC1F2 populations originating from backcrossing genetic diversity into a next-generation B line with superior breeding value.
Accomplishments
1. Elite sorghum germplasm with novel genetic diversity. 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 researchers 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 Backcross-Nested Association Mapping (BC-NAM) populations, elite sorghum plants with potentially superior breeding value including enhanced grain and forage yield were selected, evaluated by collaborators across the U.S., and are being registered for eventual distribution to breeders who will utilize the germplasm to develop higher producing and more profitable sorghum hybrids for farmers in the U.S. and worldwide.
Review Publications
Bentley, N., Grauke, L.J., Ruhlman, E., Klein, R.R., Kubenka, K.A., Wang, X., Klein, P. 2020. Linkage mapping and QTL analysis of pecan (Carya illinoinensis) full-siblings using genotyping-by-sequencing. Tree Genetics and Genomes. 16. Article 83. https://doi.org/10.1007/s11295-020-01476-6.
Porter, N.T., Burson, B.L., Washburn, J.D., Klein, R.R., Jessup, R.W. 2021. Cytogenetics and fertility of an induced tetraploid Sorghum bicolor x S. propinquum hybrid. Crop Science. 61(3):1881-1889. https://doi.org/10.1002/csc2.20482.
Fedenia, L., Klein, R.R., Dykes, L., Rooney, W., Klein, P. 2020. Phenotypic, phytochemical, and transcriptomic analysis of black sorghum (Sorghum bicolor L.) pericarp in response to light quality. Journal of Agricultural and Food Chemistry. 68:9917-9929. https://doi.org/10.1021/acs.jafc.0c02657.
