A sorghum F-box protein induces an oxidative burst in the defense against Colletotrichum sublineola

Authors: WOLF, EMILY - University Of Florida; VELA, SADDIE - University Of Florida; Cuevas, Hugo; VERMERRIS, WILFRED - University Of Florida

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2023
Publication Date: 5/24/2024
Citation: Wolf, E., Vela, S., Cuevas, H.E., Vermerris, W. 2024. A sorghum F-box protein induces an oxidative burst in the defense against Colletotrichum sublineola. Phytopathology. PHYTO-06-23-0184-R. https://doi.org/10.1094/PHYTO-06-23-0184-R.
DOI: https://doi.org/10.1094/PHYTO-06-23-0184-R

Interpretive Summary: Anthracnose is one of the most limiting diseases of sorghum worldwide. Understanding the plant defense mechanism is imperative to increase disease resistance of susceptible cultivars having good traits as a way to rely less on chemical control. The role of the resistance gene Sobic.005G172300 was studied using expression analysis and monitoring the accumulation of peroxidase and ascorbic acid. Results showed that a high expression of Sobic.005G172300 induces an anthracnose resistance response through an oxidative burst that reduces the concentration of ascorbic acid and limits the spread of the disease in infected tissue. Thus, this gene could be used to confer anthracnose resistance to susceptible varieties.

Technical Abstract: The hemibiotrophic fungal pathogen Colletotrichum sublineola is the causal agent of anthracnose in sorghum (Sorghum bicolor (L.) Moench), resulting in leaf blight, stalk rot, and head blight in susceptible genotypes, with yield losses of up to 50%. The development of anthracnose-resistant cultivars can reduce reliance on fungicides and provide a more sustainable and economical means for disease management. A previous genome-wide association study of the sorghum association panel identified the candidate resistance gene Sobic.005G172300 encoding an F-box protein. To better understand the role of this gene in the defense against C. sublineola, gene expression following infection with C. sublineola was monitored by RNA-seq in seedlings of sorghum accession SC110, which harbored the resistance allele, and three accessions that harbored a susceptible allele. Only in SC110 did the expression of Sobic.005G172300 increase during the biotrophic phase of infection. Subsequent transcriptome analysis, gene co-expression networks, and gene regulatory networks of inoculated and mock-inoculated seedlings of resistant and susceptible accessions indicated that the increase in expression of Sobic.005G172300 induces an oxidative burst by lowering the concentration of ascorbic acid during the biotrophic phase of infection. Based on gene regulatory network analysis, the protein encoded by Sobic.005G172300 is proposed to target proteins involved in the biosynthesis of ascorbic acid for polyubiquitination through the SCF E3 ubiquitin ligase, causing their degradation via the proteasome.