Collecting mating type data on nothopassalora personata directly from late leaf spot tissue of peanut

Authors: GREMILLION, SARA - Georgia Southern University; ROBERSON, GRACIE - Valdosta State University; Arias De Ares, Renee; CULBREATH, ALBERT - University Of Georgia; CANTONWINE, EMILY - Valdosta State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/2/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Abstract only.

Technical Abstract: Sexual reproduction allows organisms to create genetically-unique offspring. Pathogenic fungi such as Nothopassalora personata (Np), the causal agent of Late Leaf Spot of peanut (Arachis hypogaea L.), are known to develop resistance to fungicide treatments, a process sped up by sexual reproduction and the increase in genetic diversity in a population. While no sexual structures of Np have been observed in peanut fields in many years, it is still possible that sexual reproduction is occurring in this pathogen. Isolates of Np have been grown in pure culture, and primers have been developed to test for the presence of the two mating types, mating type 1-1 (MAT1-1) and mating type 1-2 (MAT1-2). However, culturing Np is a tedious process characterized by slow fungal growth and frequent contamination. Bypassing culturing to test peanut fields for mating types in Np populations would be advantageous in large scale survey of peanut pathogen populations. The current study asked the question “Can mating type be surveyed in populations of Np directly from late leaf spot tissue?” Fresh peanut leaves with late leaf spots were collected in Tifton, GA and mailed to Savannah, GA for processing. A total of 40 leaf spots were cut from leaf tissue and processed for DNA exaction using Zymo Research Corporation Quick-DNA Fungal/Bacterial Microprep Kit following manufacturer’s instructions. A commercially available DNA kit was selected for ease and consistency. Using two sets of mating type primers designed for Np MAT1-1 and MAT1-2, PCRs were performed to determine if the DNA extracted was of high enough quality and quantity to produce positive results. Approximately 40% of samples contained DNA that produced PCR results for one of the mating types. Possible explanations for lack of results in the remaining samples include the use of a kit that is designed for fungal tissue from culture, not from environmental samples. It is also possible that the positive DNA samples were taken from late leaf spots with sporulating occurring; therefore, more fungal material was available from which to extract DNA. Future work will test a more robust DNA extraction method that is low-cost, streamline, and effective. Late leaf spots will also be screened for sporulation before DNA is extracted to determine if the absence of sporulation correlates with low PCR success.