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ARS Home » Midwest Area » St. Paul, Minnesota » Plant Science Research » Research » Publications at this Location » Publication #412550
Research Project: Gene Discovery and Trait Improvement in Soybean, Alfalfa, and Other Legumes by Gene Editing

Location: Plant Science Research

Title: Genomes to gene-editing: Discovery and validation of candidate genes to enhance disease resistance to spring black stem and leaf spot disease

Author
item BOTKIN, JACOB - University Of Minnesota
item Curtin, Shaun

Submitted to: Congress on In Vitro Biology
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Fungal pathogens cause the majority of crop diseases leading to $200 billion in losses annually. Spring black stem and leaf spot (SBS) is a devastating foliar disease of Medicago sativa (alfalfa) affecting stand survival, yield, and forage quality. The objective of this research is to identify and validate candidate genes involved in host resistance to SBS disease. Robust resistance has been previously reported in the M. truncatula accession SA27063 (HM078). Specifically, two quantitative trait loci (QTL) rnpm1 and rnpm2 have been identified. The recessive nature of these QTL suggests a loss-of-function event in this accession, which fits the inverse gene-for-gene model. We carried out a genome assembly of HM078 to assess structural variants within the QTL regions. We identified a retrotransposon insertion in a ubiquitin conjugating E2, as well as frameshift mutations in several disease resistance related genes including NBS-LRRs, an F-box, and glycosidase. Next, the transcriptomes of HM078 and susceptible accession A17 were profiled after SBS inoculation. Several genes were upregulated in HM078 across multiple time points including lipoxygenase, 3-ketoacyl-CoA synthase, and RLK protein kinase. Isoflavone reductase and protein phosphatase 2C were upregulated in A17, while constitutively expressed in HM078. CRISPR/Cas knock-out and overexpression mutant plants for promising candidate genes were generated in the susceptible M. truncatula accession R108, and reagent efficacy was evaluated. Future research will include disease screening of these mutant lines to validate genes underlying host resistance to this destructive pathogen.