Host cell death and the onset of systemic acquired resistance: revisiting an old observation

摘要

The induction of systemic acquired resistance (SAR), the salicylic acid dependent form of induced disease resistance, is associated with host necrosis caused by either pathogens that cause local necrotic lesions or the hypersensitive response For example, localized neciotic lesions caused by Colletotrichum orbiculare or Pseudodomas syringae pv lachrymans on cucumber or neciotic stem lesions caused by Peronosopora tabacina on tobacco are examples in which a compatible interaction results in the expression of SAR Similarly, gene for gene type interactions or non-pathogen interactions that lead to the expression of the hypersensitive response can also induce the expression of SAR Hrp mutants of P syringae do not induce SAR or the HR, and this further supports a relationship between the development of pathogen induced necrosis and SAR. The correlation of pathogen-induced host cell death with the onset of SAR has been strengthened by showing that expression of SAR is positively associated with the number of necrotic lesions formed on the leaf used for induction and the level of resistance expressed systemically.