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Detection of strobilurin-resistant isolates of Mycosphaerella graminicola in Morocco
A Y Elbekali1, A Ramdani, A Siah
1Institut National de la Recherche Agronomique, BP 578, Meknès, Maroc.
Abstract:
Septoria tritici blotch caused by Mycosphaerella graminicola (anamorph: Septoria tritici) is nowadays one of the most frequently occurring diseases on both bread and durum wheat crops. Two hundred and thirty isolates of the fungus were sampled from six distinct wheat-producing regions of Morocco in order to investigate the resistance of M. graminicola to strobilurins in this country, where this fungicide class is increasingly used in wheat-pest management. A subset of 134 isolates was first collected in 2008 from Meknes-Tafilalet, Tadla-Azilal, Gharb and Chaouia. Furthermore, 96 additional isolates were sampled in 2010 from the fourth regions investigated in 2008 plus Fes-Boulmane and Doukkala-Abda. Sensitivity or resistance within the isolates were determined by screening the G143A cytochrome b substitution conferring resistance. We used a mismatch amplification mutation assay allowing the amplification of either G143 (sensitive) or A143 (resistant) allele. All the 2008 isolates were found to be sensitive since they carry the wild-type allele G143. However, 9 (9%) out of the 2010 isolates were found to contain the resistant allele A143 and therefore to be resistant. Four of them were from Gharb and five from Fes-Boulmane. This study highlighted for the first time the occurrence of strobilurin-resistant isolates of M. graminicola in Morocco. Further genetic investigations should determine if the resistant isolates emerged independently in Morocco or traveled by wind-migration from Europe.
Insights
Strobilurin resistance in Mycosphaerella graminicola, a wheat pathogen, has emerged in Morocco. Nine percent of 2010 isolates showed resistance, indicating a new challenge for wheat disease management.
Area of Science:
- Agricultural Science
- Plant Pathology
- Fungal Genetics
Background:
- Septoria tritici blotch, caused by Mycosphaerella graminicola, is a significant disease affecting wheat crops globally.
- The increasing use of strobilurin fungicides in Morocco necessitates monitoring for resistance development in M. graminicola populations.
Purpose of the Study:
- To investigate the prevalence and genetic basis of strobilurin resistance in Mycosphaerella graminicola isolates from Morocco.
- To determine if M. graminicola populations in Morocco have developed resistance to strobilurin fungicides.
Main Methods:
- Collected 230 M. graminicola isolates from six Moroccan wheat-growing regions over two years (2008 and 2010).
- Screened isolates for the G143A cytochrome b gene substitution, a known marker for strobilurin resistance, using a mismatch amplification mutation assay.
Main Results:
- All 134 isolates collected in 2008 were sensitive to strobilurins, possessing the wild-type G143 allele.
- In 2010, 9% (9 out of 96) of the isolates carried the resistant A143 allele, indicating strobilurin resistance.
- Resistant isolates were identified in the Gharb and Fes-Boulmane regions.
Conclusions:
- This study confirms the emergence of strobilurin-resistant Mycosphaerella graminicola in Morocco for the first time.
- The findings highlight the need for continued surveillance and potentially revised fungicide resistance management strategies in Moroccan wheat production.
