Classical pathogen resistance genes in plants involve specific recognition of pathogen elements with strong, localized defense responses, while non-classical resistance represents broader, less specific defense systems.
The difference between ‘classical’ and ‘non-classical’ pathogen resistance genes in plants involves different mechanisms through which plants defend themselves against pathogens. Classical resistance, often termed R-gene resistance, involves genes that encode proteins with a nucleotide-binding site (NBS) and leucine-rich repeats (LRR). These proteins can recognize specific pathogen effectors leading to strong defense responses, such as the hypersensitive response (HR) and the oxidative burst. Non-classical resistance, on the other hand, refers to a broader spectrum of defenses that do not rely on single gene-for-gene recognition. This can include mechanisms such as systemic acquired resistance (SAR) and induced systemic resistance (ISR) that provide a more general defense against a range of pathogens.