|GROBEN, GLEN - Rutgers University|
|CLARKE, BRUCE - Rutgers University|
|MURPHY, JAMES - Rutgers University|
|KOCH, PAUL - University Of Wisconsin|
|LEE, SANGKOOK - Hoseo University|
|ZHANG, NING - Rutgers University|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2020
Publication Date: 6/16/2020
Citation: Groben, G., Clarke, B., Murphy, J., Koch, P., Crouch, J., Lee, S., Zhang, N. 2020. Quantitative real-time PCR detection of Clarireedia spp., the causal agents of dollar spot in turfgrasses. Plant Disease. https://doi.org/10.1094/PDIS-04-20-0726-RE.
Interpretive Summary: Turfgrass covers millions of acres of parks, lawns, recreational fields and golf courses around the world. Turgrass dollar spot disease is destructive, widespread and persistent, with more money spent on its control than any other turfgrass pest. Symptom development typically occurs only after infections are well advanced, which makes it difficult to get the disease under control. To improve early detection of dollar spot infections, a new DNA diagnostic tool was developed. Through benchmark tests, the DNA diagnostic tool was shown to be highly sensitive and specific, detecting tiny amounts of the dollar spot pathogen in blades of turfgrass without cross-reacting with non-target DNA. The DNA diagnostic tool was sensitive enough to detect infections prior to symptom development. This sensitive new DNA diagnostic tool will be used by plant health practitioners, turfgrass breeders and agronomists to detect the dollar spot pathogens during early stages of infection, allowing targeted, time-sensitive disease treatments before the disease causes visible damage to the turfgrass plants.
Technical Abstract: Dollar spot is one of the most economically important diseases of turfgrasses. Recent taxonomic revisions have placed the dollar spot fungal pathogens in the new genus Clarireedia, with five species described. The main goal of this study was to develop a quantitative real-time polymerase chain reaction (qPCR) molecular detection assay based on the rDNA ITS to quantify the abundance of Clarireedia species from environmental (field) samples. The qPCR assay was able to detect isolates of the four tested Clarireedia species but did not cross react with non-target fungi, including closely related taxa, other turfgrass pathogens, or fungal species commonly isolated from turfgrass. The assay is highly sensitive, capable of detecting as little as 38.0 fg (3.8 x10-14 g) Clarireedia genomic DNA in three hours. The qPCR assay consistently detected Clarireedia in both symptomatic and asymptomatic creeping bentgrass (Agrostis stolonifera) foliar tissue. Clarireedia spp. were not consistently detected in the thatch or soil, indicating that these pathogens are not widely distributed in these areas of the environment. Interestingly, the pathogens were detected at low levels in asymptomatic samples of creeping bentgrass. This finding suggests that creeping bentgrass may be able to tolerate a certain quantity of the pathogens in leaves before disease symptoms appear; however, further research is needed to validate this hypothesis.