Plant Pathology (2023) 72, 708-720

Maria Cândida de Godoy de Gasparoto, Andre B. Gama, Nan-Yi Wang, Carolina S. Rebello, Megan M. Dewdney and Natalia A. Peres (2023)
Colletotrichum abscissum: Detection on symptomless citrus leaves and symptomatic citrus flowers using high-resolution melting analysis
Plant Pathology 72 (4), 708-720
Abstract: High-resolution melting (HRM) analysis has been recently applied for the diagnosis of plant diseases. This cost-effective method is advantageous over standard PCR as it does not require DNA band visualization or the use of probes necessary for quantitative PCR. Colletotrichum abscissum causes postbloom fruit drop of citrus (PFD) and survives asymptomatically on vegetative tissue. Quiescent appressoria on citrus leaves are the primary source of inoculum between flowering periods. Early PFD symptoms may be misidentified as physical damage on citrus flowers. Our objectives were to validate an HRM-based method to rapidly identify C. abscissum on citrus leaves and flowers. We screened seven previously published primer pairs and concluded that the most effective set of primers was CaITS-F and CaITS-R815. We evaluated three different DNA extraction methods, two with a purification step (DNeasy Plant Mini and PowerSoil kits) and a faster method without a purification step (buffer GEB2). We inoculated citrus leaves with C. abscissum conidial suspensions of varying concentrations and HRM analysis detected as few as 200 C. abscissum spores using DNeasy Plant Mini or DNeasy PowerSoil kits for DNA extraction. As expected, samples extracted with GEB2 buffer reduced HRM sensitivity. We further collected field samples from areas with high and low C. abscissum inoculum levels. The HRM method could detect the pathogen in high inoculum areas from both leaves and flowers regardless of the extraction method used. In summary, we describe a new molecular diagnostic tool to detect C. abscissum on citrus during its asymptomatic and symptomatic stages.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Natalia A. Peres

Research topic(s) for pests/diseases/weeds:
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Colletotrichum abscissum	Citrus (genus)