Multilocus Characterization Reveals an ITS-Defined Haplotype Associated with Pathogenic Variation in Magnaporthe...

Area of Science:

• Plant Pathology
• Mycology
• Genetics

Background:

• Rice blast, caused by Magnaporthe oryzae, significantly impacts global rice production.
• Understanding the diversity of M. oryzae is crucial for effective disease management strategies.

Purpose of the Study:

• To investigate the morphological, pathogenic, and molecular diversity of M. oryzae isolates from Punjab, Pakistan.
• To identify potential genetic markers associated with virulence and distinct morphological characteristics.

Main Methods:

• Collected 125 infected rice samples and selected 25 representative M. oryzae isolates.
• Performed morphological characterization, pathogenicity assays (including AUDPC), and multilocus molecular identification (ITS, β-tubulin, actin, calmodulin).
• Analyzed sequence data for genetic variation, including single nucleotide polymorphisms (SNPs) in the ITS region, and conducted phylogenetic analysis.

Main Results:

• Morphological characterization revealed four distinct isolate groups.
• All isolates were pathogenic, with significant variations in disease severity (e.g., RBNN-1 highest, RBNR-3 lowest).
• Molecular analysis confirmed all isolates as M. oryzae. A specific ITS haplotype (A→G SNP) was found in seven isolates, linked to a distinct morphological group and higher disease severity.

Conclusions:

• An ITS-defined haplotype is associated with a specific morphological group and increased disease severity in M. oryzae.
• This finding provides a basis for further genomic studies to explore intraspecific diversity and virulence factors.
• Highlights the importance of regional isolate characterization for targeted disease control.