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

Sydowia 77: 149-160

Published online on October 28th, 2024

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.

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