Location: Crop Germplasm Research
2022 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) 2022, in collaboration with university partners, resulted in significant progress in sorghum germplasm development, which addressed the five FY 2022 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 2022 in support of Objective 1 include the release of thirty sorghum backcross-nested association mapping families in inbred BTx623 or RTx436 genetic background. To meet associated milestones of Objective 2, phenotypic data on the 30 BC1F4 Backcross-Nested Association Mapping (BC-NAM) populations was completed in cooperation with ARS scientists at Lubbock, Texas, and collaborators at Clemson University, Kansas State University, and the University of California; this data is being distributed through a FY 2022 germplasm registration article. In addition, sequence-based genotyping of BC-NAM populations was completed in FY 2022 under an Objective 2 milestone, and that data will be distributed to researchers utilizing the BC-NAM populations and associated phenotypic and genotypic data for applied and basic research projects. Under an Objective 2 milestone, multi-location trials of testcross hybrids of select BC-NAM populations and select BC-NAM lines from all 30 populations were continued, and this data is being utilized for genomic prediction models.
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. Thirty Backcross-Nested Association Mapping (BC-NAM) populations harboring elite sorghum lines with potentially superior breeding value, including enhanced grain and forage yield, were released and registered for distribution to breeders who labor to develop higher producing sorghum hybrids for farmers in the U.S. and worldwide.
Review Publications
Fonseca, J.M., Klein, P.E., Crossa, J., Pacheco, A., Perez-Rodriguez, P., Perumal, R., Klein, R.R., Rooney, W.L. 2021. Assessing combining abilities, genomic data, and genotype x environment interactions to predict hybrid grain sorghum performance. The Plant Genome. https://doi.org/10.1002/tpg2.20127.
Fonseca, J.O., Perumal, R., Klein, P.E., Klein, R.R., Rooney, W.L. 2021. Combining abilities and elite germplasm enhancement across US public sorghum breeding programs. Crop Science. 61:4098-4111. https://doi.org/10.1002/csc2.20624.
