Phenotypic and genetic characterization of the lentil single plant-derived core collection for resistance to root rot caused by Fusarium avenaceum

Authors: Heineck, Garett; Altendorf, Kayla; Coyne, Clarice - Clare; MA, YU - Washington State University; McGee, Rebecca; Porter, Lyndon

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2022
Publication Date: 8/3/2022
Citation: Heineck, G.C., Altendorf, K.R., Coyne, C.J., Ma, Y., McGee, R.J., Porter, L.D. 2022. Phenotypic and genetic characterization of the lentil single plant-derived core collection for resistance to root rot caused by Fusarium avenaceum. Phytopathology. 112(9):1979-1987. https://doi.org/10.1094/PHYTO-12-21-0517-R.
DOI: https://doi.org/10.1094/PHYTO-12-21-0517-R

Interpretive Summary: Lentil (Lens culinaris) is a pulse crop grown for its abundant calorie content and amino acid profile, moderate drought tolerance, and ability to fix nitrogen. As the global demand for lentils expands and new production regions emerge so too have the complement of diseases, including the root rot complex. Although the predominant causal pathogen varies based on growing regions Fusarium avenaceum is often found to be an important contributor to disease. This study screened a lentil association mapping panel for resistance to F. avenaceum in a greenhouse environment. Plants were phenotyped for visual disease severity using three scoring scales and differences in biomass traits due to pathogen presence were measured. Lentil lines varied in disease severity and difference in biomass traits were found to be correlated with each visual severity estimate (r = -0.37 to -0.63, P < 0.001), however, heritability estimates were low to moderate among traits (H2 = 0.12 to 0.43). Results of a genome-wide association study (GWAS) using SNP markers derived from genotyping by sequencing revealed 11 QTL across four chromosomes. Two pairs of QTL co-located for two traits and were found near putative orthologs that have been associated with disease resistance. The identification of lentil lines that did not exhibit a difference in biomass traits may serve as parental material in breeding or in the development of bi-parental mapping populations to further validate and dissect the genetic control of resistance to root rot caused by F. avenaceum in lentil.

Technical Abstract: Lentils are an important pulse crop that has increased in popularity due to their nutritional value, tolerance to arid growing conditions, and ability to fix nitrogen. Increased intensification of lentils in Canada and the US has led to increased incidence of root rot complex, which has been known to greatly reduce lentil grain yield. Although many pathogens contribute to the root rot complex disease, Fusarium avenaceum was recently identified in a large proportion of afflicted fields in production regions across Canada and in the US Upper Midwest. Although root rot may be partially controllable through the use of seed treatments and fungicidal applications, identifying germplasm with genetic resistance is a more sustainable and economical approach. To that end, we assessed a subset of the USDA Lentil Single Plant Core Collection for resistance to root rot caused by F. avenaceum. Results revealed differences between lentil lines for disease severity and ability to accumulate biomass while under pathogen attack. This data, along with the genetic fingerprint of each lentil line, was used to conduct a genome-wide association study (GWAS) to elucidate regions of the lentil genome associated with resistance and determine putative genes responsible therein. Results of the GWAS showed 11 different regions across four chromosomes influencing disease resistance. Two of these regions were on or near genes known to control plant response to pathogen attack. Future research is currently underway to validate these results and develop markers and new resistant lentil lines.