Location: Tropical Crops and Germplasm ResearchTitle: Germplasm resources for allele mining in sorghum
Submitted to: Allele Mining for Crop Genomic Designing
Publication Type: Book / Chapter
Publication Acceptance Date: 10/1/2022
Publication Date: N/A
Technical Abstract: Sorghum [Sorghum bicolor (L.) Moench] has undergone multiple re-domestication events that led to a phenotypically and genetically highly diverse crop. Nevertheless, research has demonstrated that breeding programs worldwide have a narrow genetic base that makes the crop vulnerable to abiotic and biotic factors. The ex-situ sorghum germplasm collections provide the genetic diversity required for successful breeding programs, but the large size of most of these collections prevents the adequate phenotypic and genotypic characterization necessary for allele mining. Over the past 15 years, multiple germplasm and genomic resources have been developed to access the genetic diversity of sorghum. The development and characterization of core collections for the germplasm from ICRISAT and USDA-ARS are essential to allele mine the two largest collections. Diversity panels that consist of varieties or cultivars sharing common end uses (i.e. grain, biofuel, etc.) enable the discovery of relevant alleles for multiplepurpose breeding programs through genome-wide association studies (GWAS). The sorghum association panel (SAP), bioenergy association panel (BAP), sweet sorghum diversity panel and the world reference panel contain a combined 2,605 accessions available for allele mining. In addition, 1,176 temperate-adapted lines have been genotyped to provide an additional germplasm resource for phenotyping analysis in temperate regions. In parallel, different familial-related populations have been created to overcome the limitation of GWAS in diversity panels. Two nested association mapping (NAM) populations of 4,703 recombinant inbred lines that are complementary to the SAP and BAP can be used to validate and uncover alleles present in diversity panels. The development of two backcross NAM populations of 2,524 lines derived from crop wild relatives, cultivars and landraces, and 1,000 lines derived from a multi-parent advanced generation intercross make available additional genetic diversity for breeding programs. These diversity panels and recombinant populations are further complemented by two populations of 2,186 mutagenized lines derived from inbred line BTx623 that provide a vital resource for allele mining and for validation of candidate genes identified by QTL mapping through linkage analysis and GWAS. Certainly, the germplasm and genomic resources available in sorghum are expected to result in increased information on genetic diversity within breeding programs over the next few years.