In: Sydowia 77, (2025): 149-160; ISSN 0082-0598, DOI 10.12905/0380.sydowia77-2025-0149, Published online on October 28, 2024

Defense-related transcriptome and oxidoreductases induced in fungicide-treated onions inoculated with Setophoma terrestris, the causal agent of pink root disease

Somayeh Sadeghi, Mehdi Nasr-Esfahani*, Mojdeh Maleki, Hamid Molahoseini, Hamed Hassanzadeh Khankahdani & Mojtaba Mohammadi

1 Department of plant pathology, Islamic Azad University, Varamin, Pishva Branch, Varamin, Iran
2 Plant Protection Research Department, Isfahan Agricultural and Natural Resources Research and Education Center, Isfahan, AREEO, Iran
3 Soil and Water Research Department, Isfahan Agricultural and Natural Resources Research and Education Center, Isfahan, AREEO, Iran
4 Horticulture Crops Research Department, Hormozgan Agricultural and Natural Resources Research and Education Center, AREEO, Bandar Abbas, Iran
5 USDA-APHIS-PPQ, 1724 20th St., E., Palmetto, FL 34221, USA
*e-mails: mne2011@gmail.com; m.nasr@areeo.ac.ir; mojdehmaleki@yahoo.com; mojtaba.mohammadi@usda.gov

Sadeghi S., Nasr-Esfahani M., Maleki M., Molahoseini H., Khankahdani H.H & Mohammadi M. (2024): Defense-related transcriptome and oxidoreductases induced in fungicide-treated onions inoculated with Setophoma terrestris, the causal agent of pink root disease. – Sydowia 77: 149–160.

Mechanistic insight into stereospecific antifungal activity of fungicides against pink root disease (PRD) caused by Setophoma terrestris has not been obtained yet. In this study, we analyzed the Priaxor fungicide for inducing resistance against S. terrestris via novel defense marker genes, R1, PR5, Lectin, Lox, Osmotin and RGA29 and defense-related enzymes such as catalase (CAT), peroxidase (POX), superoxide dismutase (SOD), along with Lamardo and Rovral fungicides on three different onion cultivars.
The lowest PRD incidence was observed in Priaxor with 9.5 % compared to the non-treated controls with 47.7 %. Bulbs of Allium cepa Yellow cultivar treated with Priaxor had the highest yield followed by other cultivars. The highest gene expression was observed in Priaxor-treated cultivars followed by other fungicides ranging from 1.39–4.54-fold increase. Defense-related marker genes, R1, PR5, and RGA29, were up-regulated in onions in response to the onion pink root pathogen. Similarly, CAT, POX, and SOD activities increased in Priaxor-treated onions up to 3.6-fold. Our data indicated that various fungicides could have subtle differences in efficacy profiles inducing resistance in onion cultivars which may translate to improved management against S. terrestris as a fungal root pathogen.

Keywords: Lamardo, Priaxor, Rovral TS, CAT, POX, SOD, qRT-PCR, Yield. 2023