Pectate lyase genes from Radopholus similis and their application in pathotype identification

Area of Science:

• Plant Nematology
• Molecular Biology
• Agricultural Science

Background:

• Radopholus similis is a significant plant-parasitic nematode with two indistinguishable pathotypes: banana and citrus.
• Current methods for differentiating these pathotypes rely on inoculation tests, which yield inconsistent results due to varying experimental conditions.

Purpose of the Study:

• To investigate the parasitism and pathogenicity of Radopholus similis populations on rough lemon (Citrus limon).
• To identify a reliable molecular marker for distinguishing between banana and citrus pathotypes of R. similis.

Main Methods:

• Testing the pathogenicity and root invasion of 10 R. similis populations on rough lemon seedlings.
• Amplifying and analyzing four pectate lyase genes (Rs-pel-2, Rs-pel-3, Rs-pel-4, Rs-pel-5) from different R. similis populations.
• Assessing the expression of Rs-pel-3 across nematode developmental stages.

Main Results:

• Six R. similis populations were identified as citrus pathotypes, demonstrating pathogenicity and root invasion in rough lemon.
• Four populations were identified as banana pathotypes, lacking pathogenicity and invasion capabilities in rough lemon.
• The Rs-pel-3 gene was successfully amplified from citrus pathotype populations but not from banana pathotypes, and showed stable expression in citrus pathotypes.

Conclusions:

• The Rs-pel-3 gene is a reliable molecular marker for differentiating between banana and citrus pathotypes of Radopholus similis.
• Rs-pel-3 expression is linked to the pathogenicity of R. similis on citrus.
• This finding establishes a molecular method for identifying R. similis pathotypes, aiding in disease management.