Genomic dissection of anthracnose (Colletotrichum sublineolum) resistance response in sorghum differential line SC112-14

Authors: CRUET-BURGOS, CLARA - University Of Puerto Rico; Cuevas, Hugo; Prom, Louis; Knoll, Joseph - Joe; STUTTS, LAUREN - University Of Florida; VERMERRIS, WILFRED - University Of Florida

Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/20/2020
Publication Date: 4/9/2020
Citation: Cruet-Burgos, C.M., Cuevas, H.E., Prom, L.K., Knoll, J.E., Stutts, L., Vermerris, W. 2020. Genomic dissection of anthracnose (Colletotrichum sublineolum) resistance response in sorghum differential line SC112-14. G3, Genes/Genomes/Genetics. 10(4): 1403-1412. https://doi.org/10.1534/g3.120.401121.
DOI: https://doi.org/10.1534/g3.120.401121

Interpretive Summary: Anthracnose is one of the major sorghum diseases in tropical and subtropical regions. The most cost-effective and environmentally safe way to control this disease is through incorporation of resistance genes into commercial varieties. The anthracnose resistant response in sorghum line SC112-14 was evaluated at four locations (Texas, Florida, Georgia and Puerto Rico) and in the greenhouse against ten pathotypes. Results showed that a 1.5 Mb genomic region in chromosome 5 is controlling most of the resistance response across locations and pathotypes. The development of five high throughput genetic markers and the evaluation of more than 1,000 segregating progenies allow to narrow this genomic region to 34 kb enclosing five candidate genes. This research lays the foundation for understanding the molecular mechanism underlying the inheritance of anthracnose resistance in SC112-14 and provides the molecular markers necessary for their utilization in sorghum breeding programs.

Technical Abstract: Sorghum production is expanding to warmer and more humid regions where its production is being limited by multiple fungal pathogens. Anthracnose, caused by Colletotrichum sublineolum, is one of the major diseases in these regions, where it can cause yield losses of both grain and biomass. In this study, 114 recombinant inbred lines (RILs) derived from resistant sorghum line SC112-14 were evaluated at four distinct geographic locations in the United States for response to anthracnose. A genome scan using a high-density linkage map of 3,838 single nucleotide polymorphism (SNPs) detected two loci at 5.25 and 1.18 Mb on chromosomes 5 and 6, respectively, that explain up to 77% and 20% of the observed phenotypic variation. A bin-mapping approach using a subset of 31 highly informative RILs was employed to determine the disease response to inoculation with ten Anthracnose pathotypes in the greenhouse. A genome scan showed that the 5.25 Mb region on chromosome 5 is associated with a resistant response to nine pathotypes. Five SNP-based markers (four KASP and one INDEL) were developed and used to fine map the locus on chromosome 5 by evaluating 1,500 segregating F2:3 progenies. Based on the genotypic and phenotypic analyses of 11 recombinants, the locus was narrowed to a 470-kb genomic region. Following a genome-wide association study based on 574 accessions previously phenotyped and genotyped, the resistance locus was delimited to a 34-kb genomic interval with five candidate genes. All five candidate genes encode proteins associated with plant immune systems, suggesting they act in synergy in the resistance response.