|GONGORA-CANUL, CARLOS - Instituto Tecnologico El Llano|
|JIMENEZ-BEITIA, FIDEL - Purdue University|
|PUERTO-HERNANDEZ, CARLOS - Escuela Agricola Panamericana|
|AVELLANEDA, MAVIR - Escuela Agricola Panamericana|
|KLECZEWSKI, NATHAN - University Of Illinois|
|TELENKO, DARCY - Purdue University|
|SHIM, SUJOUNG - Purdue University|
|SOLORZANO, JOSE - University Of Minnesota|
|Goodwin, Stephen - Steve|
|Scofield, Steven - Steve|
|CRUZ, CHRISTIAN - Purdue University|
Submitted to: BMC Research Notes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2023
Publication Date: 5/4/2023
Citation: Gongora-Canul, C., Jimenez-Beitia, F.E., Puerto-Hernandez, C., Avellaneda, M.C., Kleczewski, N.M., Telenko, D.E., Shim, S., Solorzano, J.E., Goodwin, S.B., Scofield, S.R., Cruz, C.D. 2023. Assessment of symptom induction via artificial inoculation of the obligate biotrophic fungus Phyllachora maydis (Maubl.) on corn leaves. BMC Research Notes. 16. Article 69. https://doi.org/10.1186/s13104-023-06341-y.
Interpretive Summary: Tar spot is a foliar disease of corn caused by Phyllachora maydis. This pathogen produces signs in the form of dark, raised, fungal bodies that look like spots of tar and bear sexual and asexual spores. This pathogen cannot be cultured in media so the inoculum for studying tar spot must be collected from naturally infected leaves. Lack of an effective protocol to induce infection under controlled conditions limits progress in analyzing this disease. To alleviate this problem, an inoculation method was assessed under greenhouse and growth chamber conditions to test whether infection and fungal bodies of P. maydis could be induced on corn leaves. The results showed that fungal signs could be induced on inoculated leaves after 18-20 days of incubation and could be scored at the beginning of the silk growth stage, but the success rate was low at only 31%. This information will be valuable to plant pathologists and geneticists for developing more reliable inoculation methods for P. maydis in the future.
Technical Abstract: Tar spot is a foliar disease of corn caused by Phyllachora maydis, which produces signs in the form of stromata that bear conidia and ascospores. Phyllachora maydis cannot be cultured in media; therefore, the inoculum source for studying tar spot comprises leaves with stromata collected from naturally infected plants. Currently, there is no effective protocol to induce infection under controlled conditions. In this study, an inoculation method was assessed under greenhouse and growth chamber conditions to test whether stromata of P. maydis could be induced on corn leaves. Experiments resulted in incubation periods ranging between 18 to 20 days and stromata development at the beginning of corn growth stage VT-R1 (silk). The induced stromata of P. maydis were confirmed by microscopy, PCR, or both. From thirteen experiments conducted, four (31%) resulted in the successful production of stromata. Statistical analyses indicate that if an experiment is conducted, there are equal chances of obtaining successful or unsuccessful infections. The information from this study will be valuable for developing more reliable P. maydis inoculation methods in the future.