Aerobiology of the Wheat Blast Pathogen: Inoculum Monitoring and Detection of Fungicide Resistance Alleles

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Campos Vicentini, Samara Nunes ; Hawkins, Nichola J. ; King, Kevin M. ; Moreira, Silvino Intra ; de Paiva Custodio, Adriano Augusto ; Leite Junior, Rui Pereira ; Portalanza, Diego ; Garces-Fiallos, Felipe Rafael ; Krug, Loane Dantas ; West, Jonathan S. ; Fraaije, Bart A. ; De Jesus Junior, Waldir Cintra ; Ceresini, Paulo Cezar

• Document type: Journal article
• Source: AGRONOMY-BASEL; v. 13, n. 5, p. 17-pg., 2023-04-27.

Abstract

Wheat blast, caused by the ascomycetous fungus Pyricularia oryzae Triticum lineage (PoTl), is mainly controlled by fungicide use, but resistance to the main fungicide groups-sterol demethylase (DMI), quinone outside (QoI), and succinate dehydrogenase inhibitors (SDHI)-has been reported in Brazil. In order to rationalize fungicide inputs (e.g., choice, timing, dose-rate, spray number, and mixing/alternation) for managing wheat blast, we describe a new monitoring tool, enabling the quantitative measurement of pathogen's inoculum levels and detection of fungicide resistance alleles. Wheat blast airborne spores (aerosol populations) were monitored at Londrina in Parana State, a major wheat cropping region in Brazil, using an automated high-volume cyclone coupled with a lab-based quantitative real-time PCR (qPCR) assay. The objectives of our study were as follows: (1) to monitor the amount of PoTl airborne conidia during 2019-2021 based on DNA detection, (2) to reveal the prevalence of QoI resistant (QoI-R) cytochrome b alleles in aerosol populations of wheat blast, and (3) to determine the impact of weather on the dynamics of wheat blast aerosol populations and spread of QoI resistant alleles. PoTl inoculum was consistently detected in aerosols during the wheat cropping seasons from 2019 to 2021, but amounts varied significantly between seasons, with highest amounts detected in 2019. High peaks of PoTl DNA were also continuously detected during the off-season in 2020 and 2021. The prevalence of QoI resistant (QoI-R) cytochrome b G143A alleles in aerosol populations was also determined for a subset of 10 PoTl positive DNA samples with frequencies varying between 10 and 91% using a combination of PCR-amplification and SNP detection pyrosequencing. Statistically significant but low correlations were found between the levels of pathogen and the weather variables. In conclusion, for wheat blast, this system provided prior detection of airborne spore levels of the pathogen and of the prevalence of fungicide resistance alleles. (AU)

• FAPESP's process: 22/09787-2 - Detection and monitoring of fungicide resistance in populations of the wheat blast pathogen using novel spore-trapping device
• Grantee: Loane Dantas Krug
• Support Opportunities: Scholarships in Brazil - Technical Training Program - Technical Training
• FAPESP's process: 20/07611-9 - Development of a joint platform for disease epidemics monitoring and fungicide resistance detection to foster a smart program for management of wheat blast in Paraná and São Paulo states
• Grantee: Paulo Cezar Ceresini
• Support Opportunities: Regular Research Grants
• FAPESP's process: 21/03402-9 - Multi-user Equipment (MUE) approved in the grant 20/07611-9: Real Time Quantitative PCR (qPCR) Instrument
• Grantee: Gabriel Madoglio Favara
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 18/21197-0 - Novel real-time disease surveillance and fungicide resistance monitoring tools to foster a smart and sustainable crop protection platform in Brazil
• Grantee: Paulo Cezar Ceresini
• Support Opportunities: Regular Research Grants
• FAPESP's process: 19/12509-1 - Novel real-time disease surveillance and fungicide resistance monitoring tools to foster a smart and sustainable crop protection platform in Brazil
• Grantee: Silvino Intra Moreira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/50456-1 - Understanding the evolution of fungicide resistance in field populations of the wheat blast pathogen from Brazil: can we learn lessons for future disease management?
• Grantee: Paulo Cezar Ceresini
• Support Opportunities: Regular Research Grants