Association of differentially expressed R-gene candidates with leaf spot resistance in peanut (Arachis hypogaea L.)

Authors: Dang, Phat; Lamb, Marshall; CHEN, CHARLES - Auburn University

Submitted to: Molecular Biology Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2020
Publication Date: 1/5/2021
Publication URL: https://handle.nal.usda.gov/10113/7280482
Citation: Dang, P.M., Lamb, M.C., Chen, C.Y. 2021. Association of differentially expressed R-gene candidates with leaf spot resistance in peanut (Arachis hypogaea L.). Molecular Biology Reports. https://doi.org/10.1007/s11033-020-06049-3.
DOI: https://doi.org/10.1007/s11033-020-06049-3

Interpretive Summary: Early (ELS) and late leaf spots (LLS) are major fungal diseases of peanut that can severely reduce yield and quality. Development of acceptable genetic resistance has been difficult due to a strong environmental component and many major and minor genetic components that contribute to partial resistance. Resistance genes (R-genes) are an important component of plant immune system and have been identified in peanut. Advanced breeding lines from different pedigrees were evaluated for leaf spot resistance and 76 candidate R-genes expression study was applied to susceptible and resistant lines. Thirty-six R-genes were strongly regulated and significantly correlated with resistant lines, of which a majority are receptor like kinases (RLKs) and receptor like proteins (RLPs) that sense the presence of pathogen at the cell surface and initiate protection response. The largest group was receptor-like cytoplasmic kinases (RLCKs) VII that are involved in pattern-triggered kinase signaling resulting in the production reactive oxygen species (ROS). Four R-genes shared similarities to tobacco mosaic virus (TMV) resistant protein N which has shown to confer resistance to this virus. The 36 R-genes were represented in most chromosomes of the peanut genome, but no R-gene was localized to chromosome 09. Low levels of plant molecular signal in resistant lines suggest expression is tightly controlled to balance the cost of R-gene expression to plant productively. Identification and association of R-genes involved in leaf spot resistance will facilitate genetic selection of leaf spot resistant lines with good agronomic traits.

Technical Abstract: Early (ELS) and late leaf spots (LLS) are major fungal diseases of peanut that can severely reduce yield and quality. Development of acceptable genetic resistance has been difficult due to a strong environmental component and many major and minor QTLs. Resistance genes (R-genes) are an important component of plant immune system and have been identified in peanut. Advanced breeding lines from different pedigrees were evaluated for leaf spot resistance and 76 candidate R-genes expression study was applied to susceptible and resistant lines. Thirty-six R-genes were differentially expressed and significantly correlated with resistant lines, of which a majority are receptor like kinases (RLKs) and receptor like proteins (RLPs) that sense the presence of pathogen at the cell surface and initiate protection response. The largest group was receptor-like cytoplasmic kinases (RLCKs) VII that are involved in pattern-triggered kinase signaling resulting in the production reactive oxygen species (ROS). Four R-genes were homologous to tobacco mosaic virus (TMV) resistant protein N which has shown to confer resistance against this virus. When mapped to peanut genomes, 36 R-genes were represented in most chromosomes except for A09 and B09. Low levels of gene-expression in resistant lines suggest expression is tightly controlled to balance the cost of R-gene expression to plant productively. Identification and association of R-genes involved in leaf spot resistance will facilitate genetic selection of leaf spot resistant lines with good agronomic traits.