RELATIONSHIP BETWEEN PATHOGENICITY AND FUNGICIDE TOLERANCE IN THE WHEAT PATHOGEN MYCOSPHAERELLA GRAMINICOLA

Area of Science:

• Plant pathology
• Agricultural science
• Fungal genetics

Background:

• Septoria tritici blotch, caused by Mycosphaerella graminicola (Zymoseptoria tritici), is a major global wheat disease.
• Fungicide resistance and overcoming host resistance in Z. tritici compromise current control strategies.
• Understanding the link between fungicide tolerance and pathogenicity is vital for wheat disease management.

Purpose of the Study:

• To investigate the association between pathogenicity and fungicide tolerance in Zymoseptoria tritici strains.
• To evaluate the impact of fungicide tolerance levels on disease severity in wheat.
• To inform sustainable disease management practices for Septoria tritici blotch.

Main Methods:

• Eighteen Z. tritici strains with varying in vitro fungicide tolerance were isolated from Northern France.
• Greenhouse inoculations were performed on the susceptible wheat cultivar 'Scorpion'.
• Pathogenicity was assessed by measuring disease symptoms (leaf area with pycnidia).

Main Results:

• Significant variability in pathogenicity was observed among the tested Z. tritici strains.
• Strains with higher fungicide tolerance exhibited greater pathogenicity, causing more severe disease symptoms.
• A positive correlation was confirmed between fungicide tolerance and pathogenicity in Z. tritici.

Conclusions:

• Fungal genotypes combining pathogenicity and fungicide resistance are emerging in Z. tritici populations.
• The association between fungicide tolerance and pathogenicity necessitates adaptive disease management strategies.
• Integrated approaches considering both factors are crucial for durable control of Septoria tritici blotch.